tag:blogger.com,1999:blog-330195052024-03-05T13:17:56.399-08:00machine logcrochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.comBlogger219125tag:blogger.com,1999:blog-33019505.post-13753260677949354312021-03-15T12:27:00.000-07:002021-03-15T12:28:05.182-07:00Tektronix 575I purchased a Tektronix 575 in untested condition at an estate sale last Thursday. I had a selection between two complete units and a parts unit (missing CRT), and being allowed to crack the cases and peek inside I selected the unit with the least amount of dust inside.
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While this was the cleaner of the two units, it was not without its issues. Visual inspection indicated a failure in the base step generator mode switch, and less than optimal conditions with respect to the capacitors on the -15 volt rail.
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With respect to the switch, try as I might to simply reach inside and twist tines with pliers the actual repair required removal, disassembly, introducing a suitable curvature on the tines, and re-assembly/installation. I did not take many pictures of this process, as I was not in a documentation mindset (outside of taking a standard set of assembly orientation pictures some of which we see here). But I'm sure anyone can replicate the process if need be.
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Once the switch was operating satisfactorily I decided to ease it onto power and get an idea if I needed to spend another afternoon in the car and try to grab the units I had left behind the day previous due to space and money. Thankfully, there were no burn-outs; but beyond the horizontal trace mildly varying intensity in steps or moving side to side I could get no vertical deflection or movement whatsoever. Also, the CRT was (is) cock-eyed.
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Popping the side panel off and taking a look at the inside while running I noted a tube did not have a visible filament glow, nor could I spot its getter flash. Power down, grab the tube - it's hot. Sure enough, it's the 6GU7 in the vertical amplifier section - and the flash has oxidized into the tell tale white reside due to a visible crack through the base of the tube. Spend the next half hour digging through my stash to find a few candidates and show them to my tester. Insert a "fresh" 6GU7 into the vertical amplifier section and away we go.
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Where did my nice straight lines go? Also looks like I over-corrected on rotating the CRT (which is done while the unit is powered off because the adjustment assembly is currently broken and I don't feel like grabbing the yoke of the CRT while charged).
Now seems as good a time as any to replace the visibly leaking capacitors.
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Instead of waiting out a parts order I decided to use up some parts I have on hand. The original circuit section had four 2000 uf @ 20V in parallel on the lower negative voltage rail. My little assembly measures a bit more than 8000 uf and is rated at 50V. Of course, the replacement did not improve the geometry of the trace on the CRT.
It turns out the trace could be corrected through calibration controls, and a more in depth calibration will ensue now that I am reasonably sure the Tektronix 575 Transistor Curve Tracer is functional.
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It's been a while, I hope everyone is well. I'm looking forward to matching up transistors for differential stages in short order.
crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com1tag:blogger.com,1999:blog-33019505.post-21027474860047636062018-01-13T21:55:00.000-08:002018-01-13T21:55:30.545-08:00Here's a non-standard RMA build to ogleI recently put together a very non-standard (read as experimental) build. Much of the planning process and circuit level work had been completed by the time I started taking pictures, I only thought to grab the camera once things got interesting.<br><br>
The build itself contains two duplicate channels joined at the controls of an RMA Tetanus Booster (signal preamplifier) alongside a root Crustacean (three stage noise source, an early prototype of which I touched on a couple/few years back) feeding an output section & transformer.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhidL7a_XiNtsZ2Ykiw-PhcxWGkGdANIvaZnGomIasoVlzZnGiQl7ugF00m47eptBtwh2oSw0eBXYsmc2oFz7zPzIHYEKl2gQcW9L2ejPJTo2DilbJsHCygzPTK56KIF4mWBmEAWA/s1600/01_RMA130_shelltoside.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhidL7a_XiNtsZ2Ykiw-PhcxWGkGdANIvaZnGomIasoVlzZnGiQl7ugF00m47eptBtwh2oSw0eBXYsmc2oFz7zPzIHYEKl2gQcW9L2ejPJTo2DilbJsHCygzPTK56KIF4mWBmEAWA/s320/01_RMA130_shelltoside.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
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Aesthetically speaking, I wanted no visible assembly hardware topside. This required fabricating brackets that would secure the wood side cheeks from the inside. <br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDXIDT9GjeRxNN4vDT5zjpDoWoNvRAcPkZcZO9eeYpfUEIxDQ7YjoVU8aFswF7qn9ci12_eXxkt_a_mljEyomDfrhwTEvFzIVyfy97ndxWxYT2JXnkGyjLACxj8eg1j4m6-Rbi2g/s1600/02_RMA130_mountingtabs.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDXIDT9GjeRxNN4vDT5zjpDoWoNvRAcPkZcZO9eeYpfUEIxDQ7YjoVU8aFswF7qn9ci12_eXxkt_a_mljEyomDfrhwTEvFzIVyfy97ndxWxYT2JXnkGyjLACxj8eg1j4m6-Rbi2g/s320/02_RMA130_mountingtabs.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
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The brackets were marked for alignment and drilled to accommodate jacks and switches which would double as mounting hardware. Working in thinner wall (20 or 22 gauge) mild steel makes it possible to build with a stack of multiple metal elements and not run out of thread.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-5BhkRF9uq3Dk903GoUdteFDDuO5vWLac8XskhLsDVCWY73_QUCMdKRyZ1bH_wrYoCf2UTFA2C9HDFyLo5lh0KQxPU-R9WD3_xRogSzYO8szT5jg07qFbv8ZWKrvxfGiV_pjMiw/s1600/03_RMA130_LEDmounting.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-5BhkRF9uq3Dk903GoUdteFDDuO5vWLac8XskhLsDVCWY73_QUCMdKRyZ1bH_wrYoCf2UTFA2C9HDFyLo5lh0KQxPU-R9WD3_xRogSzYO8szT5jg07qFbv8ZWKrvxfGiV_pjMiw/s320/03_RMA130_LEDmounting.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
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The cracked glass LED lens is held in place with a spring resting on the LED bracket, straddling the LEDs. The LEDs themselves needed a flat ground on the outermost face (in relation to their triangle) of the light emitting "dome" to allow the half inch nominal diameter spring to rest on the bracket and not teeter on an LED.
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDYUh04z2Tq_NzOOr8sgpMkyZPz7zYm15Nqh3Z3J8b6ByYxHfP6yaZ4eK7ZwnqdN2NdZV0oz9yxL8_P409r3Ii7pd_qhoECsFcntBmkgDcXj-5uA_qbhLLWHceTCYMUT3LRMo8NA/s1600/04_RMA130_emptyshell.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDYUh04z2Tq_NzOOr8sgpMkyZPz7zYm15Nqh3Z3J8b6ByYxHfP6yaZ4eK7ZwnqdN2NdZV0oz9yxL8_P409r3Ii7pd_qhoECsFcntBmkgDcXj-5uA_qbhLLWHceTCYMUT3LRMo8NA/s320/04_RMA130_emptyshell.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
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Trial run of fitting the sides to see how it sits (corrective twisting at this stage before I loaded up on more hardware proved wise), and a test to make sure I could install the cracked glass from "beneath".<br>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3Pgj7eXCaeSh7kLu74ieIw1nRbE5dTPwKI0ofDuqzo0pnh-rv1NCzlwDT0FZKW6VdbzOxk3D67UvfI43I6gRQDkk8Wl4Fpm6_GQlSpaBWMpCQCpYNZ_cNw5xa87JG1Sjk3-3uUA/s1600/05_RMA130_knobsizing.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3Pgj7eXCaeSh7kLu74ieIw1nRbE5dTPwKI0ofDuqzo0pnh-rv1NCzlwDT0FZKW6VdbzOxk3D67UvfI43I6gRQDkk8Wl4Fpm6_GQlSpaBWMpCQCpYNZ_cNw5xa87JG1Sjk3-3uUA/s320/05_RMA130_knobsizing.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
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I knew the markings were sized to the knobs as I had a doweled dummy knob while labeling, but I had to lay my eyes on the finished geometry with the glass in situ.<br>
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A problem I have fallen into in the past is that of proceeding on the externals before I have a 100% clear idea of how the interior elements are going to sit. This build proved no different. <br>
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Initially my thought was to bend some L profile shelf pieces that would secure to the inside of the wood side cheeks, providing a mounting point to tie a metal plate from one "wall" to the other. This would double as another structural tie while it provided a method to mount the number of circuit boards this build required. The mock up pictured was placed with this approach in mind, but visualizing the build methods it would take to pull it together while allowing future access for repair/etc was not working out with the area I had to work with.<br><br>
The most obvious issue revolved around the output stages (resting on the rear rim), I had originally thought to mount those tucked behind the audio jacks at rear, but the output transformers were an interference fit even before introducing a mounting solution.
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBZPgN4maABdi43sXMtPPCRXL-QdEEqE6KP8boy8N6zhQHIghn7t2X1dKi-AHgPnuATasB8jAPzZniK5T-nJPc57vMQtj84CfdRTNXb8bdiGPklEq1c3v1ohut0PlO5sypITXJZA/s1600/07_RMA130_outputnosecone.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBZPgN4maABdi43sXMtPPCRXL-QdEEqE6KP8boy8N6zhQHIghn7t2X1dKi-AHgPnuATasB8jAPzZniK5T-nJPc57vMQtj84CfdRTNXb8bdiGPklEq1c3v1ohut0PlO5sypITXJZA/s320/07_RMA130_outputnosecone.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
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The solution for where to put the output section offered itself by way of unused space in the front of the unit, past the switches which had proven themselves too "deep" to allow spanning that area with a circuit board. I bent up a mounting plate that would nest in the nose and secure via the bank of switches. Strips were cut into the metal and folded around the transformers to keep them in place.<br>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpvecxW01Fs9yT7c2iejZaAe87MYP8lhXV1GsrGNSMHGWVQw65Eee2h6JLd5G16Lzmj5PzT7okpOdgMqBTKMd5muHSO2WzGv5Sp-XEmVsjnrPdp0a3pTcgPLvV8zjNl52kFeh5IQ/s1600/08_RMA130_sidecheeks.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpvecxW01Fs9yT7c2iejZaAe87MYP8lhXV1GsrGNSMHGWVQw65Eee2h6JLd5G16Lzmj5PzT7okpOdgMqBTKMd5muHSO2WzGv5Sp-XEmVsjnrPdp0a3pTcgPLvV8zjNl52kFeh5IQ/s320/08_RMA130_sidecheeks.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
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Meanwhile the wood cheeks were shown another sanding pass and a coat of tung oil.
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The output subassembly tucked right into place, and the load on the switch hardware is minimal as everything is a tight and flush fit. The front proved a better choice for mounting, as that is where the effect bypass and output polarity switches live, so wiring runs are shorter this way than as originally designed.<br>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7PYwVSRulWXANz7qZzuBapACymS5xOouO-XPR9WnVxFhYLSbf7fD45Dz5C2qPNmylP5jlB_UMyJHJoZJrEpSY7ih4Ab_kME9PVOJcHWDNK2nQ9UnscZ0ty32WQM5Y2wnERCFp4A/s1600/10_RMA130_outputswitchclearance.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7PYwVSRulWXANz7qZzuBapACymS5xOouO-XPR9WnVxFhYLSbf7fD45Dz5C2qPNmylP5jlB_UMyJHJoZJrEpSY7ih4Ab_kME9PVOJcHWDNK2nQ9UnscZ0ty32WQM5Y2wnERCFp4A/s320/10_RMA130_outputswitchclearance.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
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4PDT bypass switch (true bypass with no LED indicator for two channels) displays plenty of room between itself and the transformer legs.
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirtBeutiBAAi5KsCYqPlN1uT1dM-_OaaatbuhJZWBSF6lnpPfV3bHHOoWW_HfRDbAcJmxK35SNUxXf_3kwg-_nFUZ8KBXt0McSuNYc2zIcV1aalhIFDiDj8EnZ2OoELhb9Ayguuw/s1600/11_RMA130_inputmounting.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirtBeutiBAAi5KsCYqPlN1uT1dM-_OaaatbuhJZWBSF6lnpPfV3bHHOoWW_HfRDbAcJmxK35SNUxXf_3kwg-_nFUZ8KBXt0McSuNYc2zIcV1aalhIFDiDj8EnZ2OoELhb9Ayguuw/s320/11_RMA130_inputmounting.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>
Since I had freed up the rear space in the enclosure by installing the output stages up front, it only made sense to mount the input sections at the back and buy myself a little needed elbow room for the other three boards. This was facilitated by yet another bracket; this one spanning the audio jack & DC inlet plate and bending down for the mounting point.<br>
<br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_n2pbVEPSXXaXt1Ah2xF7MR8quCuQkMMWZIRre5bLJFyh_DU4Zp-pNd2B1h8PCWoNmoqJ5hDzyfuK-BI-J1wv5BkxB_4xZfIpjLReRo5e9q1GjD3vLOVYtxoE9z56g_EDcLa0Ng/s1600/12_RMA130_bracketinterference.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_n2pbVEPSXXaXt1Ah2xF7MR8quCuQkMMWZIRre5bLJFyh_DU4Zp-pNd2B1h8PCWoNmoqJ5hDzyfuK-BI-J1wv5BkxB_4xZfIpjLReRo5e9q1GjD3vLOVYtxoE9z56g_EDcLa0Ng/s320/12_RMA130_bracketinterference.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>
Marked in black is an interference fit that occurred because I fit the rear mounting bracket to the outer shell without the side mounting brackets in place. The side brackets are fit to the shell, so I cannot simply swap the mounting bracket into the middle position I have to trim the bent profile down. It was easy enough to avoid kinking my angle with snips.<br>
<br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjFQKlAbb6BaNr7R9PJQ7X97GZxf_i7RE4h_syNLobebTb_FSmlZolWdyeRtj17Arz0buaLcBht4zkXjTU4wjeHuBydYJytJ4Jal99BuTDwAAa0FZFLU5ZsQjjNPY3apvLXyMPFw/s1600/13_RMA130_noseclipped.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjFQKlAbb6BaNr7R9PJQ7X97GZxf_i7RE4h_syNLobebTb_FSmlZolWdyeRtj17Arz0buaLcBht4zkXjTU4wjeHuBydYJytJ4Jal99BuTDwAAa0FZFLU5ZsQjjNPY3apvLXyMPFw/s320/13_RMA130_noseclipped.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>
Contrary to the situation at the rear, the front carrier is tight enough to the outer shell that I opted to guide the front side bracket proud of the PCB mount. I considered trimming them to prevent any overlap, but since the front subassembly is carrying transformers I figured the additional securing was preferable.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHZx2Pp9evJ6-PKfb_9-PM_lau5Oi-7InQeM7l4BtBaZ52yuDRztdMHc8IVIgu3B10uIRs9eEulzFhrEGOfLTA4a1cBir5Tz7RzdzC85lQ8ShlMzQL6Lugs98vXDgu-I0MsieUGA/s1600/14_RMA130_controlmockup.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHZx2Pp9evJ6-PKfb_9-PM_lau5Oi-7InQeM7l4BtBaZ52yuDRztdMHc8IVIgu3B10uIRs9eEulzFhrEGOfLTA4a1cBir5Tz7RzdzC85lQ8ShlMzQL6Lugs98vXDgu-I0MsieUGA/s320/14_RMA130_controlmockup.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>
Since I nixed the idea of wall mounting my main PCB mounting plate, I fabricated Z profile mounting legs affixed by the potentiometers. This will allow my mounting all circuitry off the bottom plate, which is a design method I'm striving for in the future.<br>
<br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqbccvbIPOpDyNvS6I_axGXXAZAcdSdKsJWioMmixo-x4gyaRNDNaq3tRW7we0GedxtKVM42lCsoK-xU7WZHwsHyeNa_BL5y_b-iNnKkDRpZm4i320wPM1cNonLS3-H_6qEGH5xA/s1600/15_RMA130_PCBmountmockup.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqbccvbIPOpDyNvS6I_axGXXAZAcdSdKsJWioMmixo-x4gyaRNDNaq3tRW7we0GedxtKVM42lCsoK-xU7WZHwsHyeNa_BL5y_b-iNnKkDRpZm4i320wPM1cNonLS3-H_6qEGH5xA/s320/15_RMA130_PCBmountmockup.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a><br><br>
I cut paper into a shape defined by two Crustacean root PCBs into the shape you see here for proof of fit.<br>
<br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSeURHP0qjlLnf8TEu5XeYLjQ19SBSQCEdJMdGvdHLljE4QYoIIWR2TRjiA2S6vG8BdJ3hdLWiaWRvmowxrCNCqeU1wVWS2uPpEiP0QtcVmkLIRlYUBYqEcho0lWvh3xisTGiyiA/s1600/16_RMA130_PCBmountmockup.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSeURHP0qjlLnf8TEu5XeYLjQ19SBSQCEdJMdGvdHLljE4QYoIIWR2TRjiA2S6vG8BdJ3hdLWiaWRvmowxrCNCqeU1wVWS2uPpEiP0QtcVmkLIRlYUBYqEcho0lWvh3xisTGiyiA/s320/16_RMA130_PCBmountmockup.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>
So far so good, and there remained space for the third, LED drive circuit board.<br>
<br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQ4eoaOpSCt0bzlDDXMq-h8I8Yf_VdRZf75uhcYoAlcKoNK4AD-yBn_UOl37GRziHBYplKtO2UrIXNy3bN0nKmmQ4SEON__UNsnF-u5jZ5g9T9mnw3aHGRGBlnzxBElNUFnC173Q/s1600/17_RMA130_summing.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQ4eoaOpSCt0bzlDDXMq-h8I8Yf_VdRZf75uhcYoAlcKoNK4AD-yBn_UOl37GRziHBYplKtO2UrIXNy3bN0nKmmQ4SEON__UNsnF-u5jZ5g9T9mnw3aHGRGBlnzxBElNUFnC173Q/s320/17_RMA130_summing.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>
On to wiring the control path. I had, in the infancy of this project, figured I would just flying wire finish the 10K summing resistors that join the post volume control sections of white noise, low pass noise, variable crackle, and audio input. Having developed a better feel of the cramped intensity this build was turning into, I added yet another circuit board with two 4 into 1 resistive mixers mounted to a shorter Z bracket.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5nQ2Quoj4mLn4M5pzwL8_OBy_EXm5mdex_7zmh9Fj5u9-PZwNg_Y4yun6R9lJpx8bkKJNnwQ3uwCeEjpDLIiSNupkHPK04pcbtDia_fZhS027sMd9ZTCewFbfLMAXiiF_3eXY5Q/s1600/18_RMA130_wiring1.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5nQ2Quoj4mLn4M5pzwL8_OBy_EXm5mdex_7zmh9Fj5u9-PZwNg_Y4yun6R9lJpx8bkKJNnwQ3uwCeEjpDLIiSNupkHPK04pcbtDia_fZhS027sMd9ZTCewFbfLMAXiiF_3eXY5Q/s320/18_RMA130_wiring1.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>
The installed circuits were already wired, demanding a flying wire management system. <br><br>
If you look close, you can see that the two inner mounting bolts for the Tetanus Boosters have been shortened. This was due to an un-pictured test fit involving the LED driver board.
<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOrlgCdENJu-vIXXBby39BCWZKxa0TG_CVydicla0k7FijV8efNwwxyfoTB-2MNiMl7hqovg99a3FwCxtgOWxkeUK1r7IdaQEE4oL44xtI5H1CLSBBgp08YOQV-5h0JWvFm2dArQ/s1600/19_RMA130_rearclearance.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOrlgCdENJu-vIXXBby39BCWZKxa0TG_CVydicla0k7FijV8efNwwxyfoTB-2MNiMl7hqovg99a3FwCxtgOWxkeUK1r7IdaQEE4oL44xtI5H1CLSBBgp08YOQV-5h0JWvFm2dArQ/s320/19_RMA130_rearclearance.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>
If you sight up the grounding lug of the Switchcraft jack you'll observe a resistor lead that looks as if it would potentially offer a short circuit condition if the jack should become loose and spin. The upside is that exposed lead is itself at ground potential.<br><br>
I had employed the Switchcraft 12A to normal the A channel output to the B channel input when no cable was inserted on B in, but it was a very noisy connection (yes, I realize this thing is generating noise, but there's a difference) so I clipped that wire out. I reason that the operator can still cascade the two sides with a short cable, but at that point the massive influx of noise is no longer a design sanctioned element and so they can either be delighted at the discovery of this behavior or decide it isn't a swell condition as I did.<br>
<br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjVy0KbY06UXmylBVheotgWeAR0FjlXiQG20Q1UpSvnlVNThv9SHkOwbv9SpGyifoL7ZfjZhdHTTKStMxFApTU_d9XbkLQHGKwj0FXnjFkt0LUcChdZjjh01BC5sokO72kjdpMUA/s1600/20_RMA130_wiring2.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjVy0KbY06UXmylBVheotgWeAR0FjlXiQG20Q1UpSvnlVNThv9SHkOwbv9SpGyifoL7ZfjZhdHTTKStMxFApTU_d9XbkLQHGKwj0FXnjFkt0LUcChdZjjh01BC5sokO72kjdpMUA/s320/20_RMA130_wiring2.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a><br><br>
Wiring begins. Hey, I'm going to need to establish some guide marks to make sure I don't accidentally cross pollinate the channels.<br>
<br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXAZh40K5y1az2tR57nVAJonI_N8r62XP4G3jGzAOIPFkPNEc2SIcL_CoFHEdS-oJ87CEzKfUGs_OnjxdRD7MpcnR7g1ecrU_7S6EjtXXBHfRQLvyAgerUSzhGLBv6abuNXGy1fQ/s1600/21_RMA130_wiringfront.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXAZh40K5y1az2tR57nVAJonI_N8r62XP4G3jGzAOIPFkPNEc2SIcL_CoFHEdS-oJ87CEzKfUGs_OnjxdRD7MpcnR7g1ecrU_7S6EjtXXBHfRQLvyAgerUSzhGLBv6abuNXGy1fQ/s320/21_RMA130_wiringfront.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a><br><br>
More flying wires.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNPqWf60_CNdKpk2skBnn822VV1ZiJlaCwuJ3vYS18TyCTyANZku3sAKFZnCC59GckUCRsM8cvSUHhvJNZCs1YOXVaJBZE_gcfUP9DeSlWqZtZ9n9F9UhbRf3PS9L4lmNbSs_gEA/s1600/22_RMA130_wiringrear.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNPqWf60_CNdKpk2skBnn822VV1ZiJlaCwuJ3vYS18TyCTyANZku3sAKFZnCC59GckUCRsM8cvSUHhvJNZCs1YOXVaJBZE_gcfUP9DeSlWqZtZ9n9F9UhbRf3PS9L4lmNbSs_gEA/s320/22_RMA130_wiringrear.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>
Less flying wires.
<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwzrK3jU6V7FOYxUjWuMcRgfWPRUiwB_IC9nTwP69gv_sDxyDXQkHFlNgJ-aEp0Pg1-QpRx2CkQ8HZ4ZkbzP1Aq-K49jsAvcKF7YMck7QtVhJpqqMEAORQJcQJblg26Xq9RQsoAQ/s1600/23_RMA130_top.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwzrK3jU6V7FOYxUjWuMcRgfWPRUiwB_IC9nTwP69gv_sDxyDXQkHFlNgJ-aEp0Pg1-QpRx2CkQ8HZ4ZkbzP1Aq-K49jsAvcKF7YMck7QtVhJpqqMEAORQJcQJblg26Xq9RQsoAQ/s320/23_RMA130_top.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>I'm pretty sure this picture marked the end of a day, and I just wanted to see what a complete build was going to look like.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWA48IP-Zf3rToxsWUBbQxb9kSdWYAUUkTcjGJsnX57Bp-Q_dRmYo9G-WaupBThbOXhwHVTECyO8rHdDAgwr7nBsy77RGyt6OKPLTBC_fV_pHs4tZ-fiI9NjSDtDoEUoqJfFVBDw/s1600/24_RMA130_PCBplatepattern.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWA48IP-Zf3rToxsWUBbQxb9kSdWYAUUkTcjGJsnX57Bp-Q_dRmYo9G-WaupBThbOXhwHVTECyO8rHdDAgwr7nBsy77RGyt6OKPLTBC_fV_pHs4tZ-fiI9NjSDtDoEUoqJfFVBDw/s320/24_RMA130_PCBplatepattern.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>I bolted the paper pattern in to transfer mounting holes.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHGfWKCAIHyxG0pOwtOySpGV_bkbblxvKNHwm9atW3Cs3QBrZr51XCbC_xth7dvjRJzsK_MpKM5O2mi_rj9Jq0R5-_D2g3Ffn272jnzEZDNH_YOnJWJL0u-T5OvcPfg1_lUxJ7aA/s1600/25_RMA130_PCBclearance.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHGfWKCAIHyxG0pOwtOySpGV_bkbblxvKNHwm9atW3Cs3QBrZr51XCbC_xth7dvjRJzsK_MpKM5O2mi_rj9Jq0R5-_D2g3Ffn272jnzEZDNH_YOnJWJL0u-T5OvcPfg1_lUxJ7aA/s320/25_RMA130_PCBclearance.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a><br>
<br>
I'm skeptical that there's enough space in that gap between the trimpot and straight edge to allow the metal plate and mounting hardware, so the "downhill" PCB will be rotated 180 degrees to shift the taller stuff to the rear.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicueWGLNeLcJMOZ1a7fH9lY8OZxpQGh-I8jFIdBtVPADlwh7-ymTfSFh7rQWdqsu522l_IaJUjHge-Vxi5CVMYf8q91uhOG3T0yT_KhTgjSL2enusqEg8Zta_UfkXuSOaPu7ZLrA/s1600/26_RMA130_PCBstack.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicueWGLNeLcJMOZ1a7fH9lY8OZxpQGh-I8jFIdBtVPADlwh7-ymTfSFh7rQWdqsu522l_IaJUjHge-Vxi5CVMYf8q91uhOG3T0yT_KhTgjSL2enusqEg8Zta_UfkXuSOaPu7ZLrA/s320/26_RMA130_PCBstack.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a><br>
<br>High time to do another fit check on the LED driver board. This is so the LED will change depending on output signal strength, it could be a ridiculously small printed circuit board with SMT, but no, I'll go with socketed DIP on a huge chunk of proto-board instead. <br><br>
Party animal.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZfnITcSIHI3pYCdHAmJOOtQikquTjNAHsdhX3-Wn-wbCj1Dt1RP52ZF4w9usQiNFSfMu6p8NreLuJzg80Fd5QpiHOHF5owHUbv5jkdfuMcQU0bel9zky8R-xQ_nQnQBbRQg-pxA/s1600/27_RMA130_PCBroom.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZfnITcSIHI3pYCdHAmJOOtQikquTjNAHsdhX3-Wn-wbCj1Dt1RP52ZF4w9usQiNFSfMu6p8NreLuJzg80Fd5QpiHOHF5owHUbv5jkdfuMcQU0bel9zky8R-xQ_nQnQBbRQg-pxA/s320/27_RMA130_PCBroom.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a><br>
<br>There's plenty or room for the second Crustacean, so let's get this party going.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiOysYjYdwvoZD4zLLt_wkoV61nSzQXoXCvvN5e7ly6Xu5UuHGOo3sNxD9kFYNgKYusTbN8lf160nNaOm7MHy0JCDp3zdtZ7wTv1jGEx-hG42f4GE7FOqupfpwrwfbGqscH45dBA/s1600/28_RMA130_PCBplate.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiOysYjYdwvoZD4zLLt_wkoV61nSzQXoXCvvN5e7ly6Xu5UuHGOo3sNxD9kFYNgKYusTbN8lf160nNaOm7MHy0JCDp3zdtZ7wTv1jGEx-hG42f4GE7FOqupfpwrwfbGqscH45dBA/s320/28_RMA130_PCBplate.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a><br>
<br>An artifact of geometric constraints is offsetting a pair of PCBs that defined the size & shape of the plate on which they are mounted.<br><br>
I know, if this was part of a rocket going into space the baseplate would be define by mounting points instead of edge cuts, but I'm a simple man.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3MRtaA0USRttlodcZKljS4xkWXeoe6K7EoO500jBhbUUZnsPWdYLorHf6FTQWs9169Gj-JSDllV1mOxD_hUu-9jcLx0ZWWR2SrOwzUZONTwsz155NeHkDHRNcAPN4iIKr4txHlQ/s1600/29_RMA130_PCBplatefit.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3MRtaA0USRttlodcZKljS4xkWXeoe6K7EoO500jBhbUUZnsPWdYLorHf6FTQWs9169Gj-JSDllV1mOxD_hUu-9jcLx0ZWWR2SrOwzUZONTwsz155NeHkDHRNcAPN4iIKr4txHlQ/s320/29_RMA130_PCBplatefit.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br>
<br>Something about this point really drove home the light at the end of the tunnel aspect for me.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgp-sOUQz9rXsHBz4dEceGCbpUKIQLSzDwvyw74nvhF92ZrRukb_4OckPbwNUZIHVF9OALBceWhFrvLkT_uDrw1xK6xmVP62mqQU_nWfZUTgzJBpobqjvcfwJGSjMtBhQDOAVxfog/s1600/30_RMA130_PCBplateclearance.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgp-sOUQz9rXsHBz4dEceGCbpUKIQLSzDwvyw74nvhF92ZrRukb_4OckPbwNUZIHVF9OALBceWhFrvLkT_uDrw1xK6xmVP62mqQU_nWfZUTgzJBpobqjvcfwJGSjMtBhQDOAVxfog/s320/30_RMA130_PCBplateclearance.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br>
<br>I like my tolerances tight. <br>
<br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMePG_jS8JO7o5dZMRtP5i3ka4SYD2lF0uWuJlT8qULWyqHFjCgTSCGdWAaDZ3Ks38UX3zIt4Os9QgysZM5toLbyfWv8NktsoTJEOGL3I0EcO20ttwTujO0CJOa7GtneUEJogLlA/s1600/31_RMA130_stuffed.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMePG_jS8JO7o5dZMRtP5i3ka4SYD2lF0uWuJlT8qULWyqHFjCgTSCGdWAaDZ3Ks38UX3zIt4Os9QgysZM5toLbyfWv8NktsoTJEOGL3I0EcO20ttwTujO0CJOa7GtneUEJogLlA/s320/31_RMA130_stuffed.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br>
<br>STUFF IT! STUFF IT! GO GO GO<br><br>
It's risky, these stretches that one clings to as being a final pass. I know this. I've dug myself into plenty of holes, but I'm usually able to dig myself back out...<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwbc3FWdMLovYB7DbEcX96WJryfe6Gt_RsfVICnJBcAv_jDw_DwUeP8O-7Dh3Rzz6ltTUYfIA92lXYkaCDPNsmATNASJ6ZXhDF2XKF1csI2JDcadot06W6o_lZczA0ValwRz9Deg/s1600/32_RMA130_gutoverhang.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwbc3FWdMLovYB7DbEcX96WJryfe6Gt_RsfVICnJBcAv_jDw_DwUeP8O-7Dh3Rzz6ltTUYfIA92lXYkaCDPNsmATNASJ6ZXhDF2XKF1csI2JDcadot06W6o_lZczA0ValwRz9Deg/s320/32_RMA130_gutoverhang.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br>
<br>Final placement mock-up is looking okay.<br>
<br>At this point, with this particular build, I'm hazarding into race mode, because everything is over due. I could weave a long tale as to why this is the case, but in the end things we've heard a thousand times before are boring retreads not worth mention. Suffices to say I am motivated to complete as soon as possible.<br><br>
Meanwhile there is a niggling sense that I have overextended myself and am operating in a state of unhinged overconfidence.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi809k3JEttNHm070cQmvF2ixggjmRYoV4tKIJHYcH8kfzy-Iq0cLXV76gRpH_eQgVKcfwctpuxwoS2ZFQtYrZ38065ShFqyd52piFXzAikaKWxonDJT-af6o9-KTbluwPn9EEn0A/s1600/33_RMA130_guts.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi809k3JEttNHm070cQmvF2ixggjmRYoV4tKIJHYcH8kfzy-Iq0cLXV76gRpH_eQgVKcfwctpuxwoS2ZFQtYrZ38065ShFqyd52piFXzAikaKWxonDJT-af6o9-KTbluwPn9EEn0A/s320/33_RMA130_guts.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br><br>LED board is not wired up and accounts for all the flying leads topside. I have not wired up the output section to polarity switch, because I want to look at a trace on the scope to prove I adhere to the labeling scenario I have already established on the faceplate.<br><br>
Aside from that, everything is wired up and ready for test.<br><br>
You read that correctly.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgT7wR-XFnYbJrEooPrMrTpeV3qG75jFlZCSdJTidXdAjHHQ1h7bl_aCIWmBOku-8hdEDEKU3JGQVOxdyiOVii0ijsFJnAGEQYeKMgf36H9zcwwIj7YnX_o6xaHqcdLGUPpbsBMjg/s1600/34_RMA130_potrewire.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgT7wR-XFnYbJrEooPrMrTpeV3qG75jFlZCSdJTidXdAjHHQ1h7bl_aCIWmBOku-8hdEDEKU3JGQVOxdyiOVii0ijsFJnAGEQYeKMgf36H9zcwwIj7YnX_o6xaHqcdLGUPpbsBMjg/s320/34_RMA130_potrewire.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br>
<br>The gain control had been wired backwards. An annoying fix, but not terrible.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzpW4xcHZWZW4T09jnWB64Ra7dqKSB0HlygOIqaXuGiTGOLmWs1BdLIc2BTMNGRQ18hWZ7tXGkfuNc31b6bgCZPvNnvnX9LyEHmLkO7axon8hUvZq_5wQxcUDRT55g34obFSLxDA/s1600/35_RMA130_interiorcomplete.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzpW4xcHZWZW4T09jnWB64Ra7dqKSB0HlygOIqaXuGiTGOLmWs1BdLIc2BTMNGRQ18hWZ7tXGkfuNc31b6bgCZPvNnvnX9LyEHmLkO7axon8hUvZq_5wQxcUDRT55g34obFSLxDA/s320/35_RMA130_interiorcomplete.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br>
<br>Confirmation of circuit operation paved way to wiring up the LED system...<br> <br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilCwV_MjwD3CIHIRQebMGFHf422RvCLffMn4WmMnAkwc0XTtURC9Vr_lCtFU3kSGpP192gynH6w3LjhYzpIT-Cmbtd88RP27Y37cZQ_BR9cPizkWhiFRXq9TOUkQY0wp75nZMmQA/s1600/36_RMA130_finishoverhang.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilCwV_MjwD3CIHIRQebMGFHf422RvCLffMn4WmMnAkwc0XTtURC9Vr_lCtFU3kSGpP192gynH6w3LjhYzpIT-Cmbtd88RP27Y37cZQ_BR9cPizkWhiFRXq9TOUkQY0wp75nZMmQA/s320/36_RMA130_finishoverhang.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>
<br>
<br>...which overhangs the baseplate closure plane by a healthy degree. I doubled the nuts on which the Crustacean boards rest to clear the metal plate mounting screws, and as a result pushed everything outward by the width of a nut. I resolved this by folding a hem on the (insulated) baseplate which results in a little more interior headroom.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwtuulDKGaOsh4HD7On0QI9jF1hly_ZzXOXnSRJXIteR60gfUDmrmJopQbhH-xLiu-KpGWab54wTp3Fv1_EhBCBzsz2AisgJRQ2-wwZx7oPTCQrRCe9h4Amae7COMLFBb_2sr9jg/s1600/37_RMA130_exterior.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwtuulDKGaOsh4HD7On0QI9jF1hly_ZzXOXnSRJXIteR60gfUDmrmJopQbhH-xLiu-KpGWab54wTp3Fv1_EhBCBzsz2AisgJRQ2-wwZx7oPTCQrRCe9h4Amae7COMLFBb_2sr9jg/s320/37_RMA130_exterior.JPG" width="320" height="262" data-original-width="1000" data-original-height="820" /></a>
<br>
<br>Out the door the same day it was finished, but it was a fun while it lasted.<br><br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-sZqxiT88xRvVCI4wvfZ5EogIJkoKI-3g7w-52fUZ6UF3HExCij2_h8m5oSC1Snts-X5LVOKY0NXStMHorIfmvC4R7TYZwV5qF8GIAgn0UjVgP3VjUYZ5_arE6ozUH-BPUQ9zag/s1600/38_RMA130_bottom.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-sZqxiT88xRvVCI4wvfZ5EogIJkoKI-3g7w-52fUZ6UF3HExCij2_h8m5oSC1Snts-X5LVOKY0NXStMHorIfmvC4R7TYZwV5qF8GIAgn0UjVgP3VjUYZ5_arE6ozUH-BPUQ9zag/s320/38_RMA130_bottom.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a>crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com1tag:blogger.com,1999:blog-33019505.post-32174619712935262172017-12-18T08:10:00.000-08:002017-12-18T08:13:38.819-08:00HELLO!<br><br>
My, my, it has been a while.<br><br>
The fault is entirely mine. I've been immersed in the doings of <a href="https://www.rochambeau.net">Rochambeau Musical Apparatus</a href> for the past couple/few years now and it has sort of locked my time away from this particular avenue of sharing. While I will admit that what I am doing with RMA is in and of itself blog-worthy from a content point of view, it is also a deeply personal journey through mis-applying engineering, empirical education, and general mayhem and I have decided that my process functions better outside the spotlight and on my terms.<br><br>
I want to stress that this is not due to overt secrecy; if anyone has any questions regarding any of the RMA designs or specific builds I should be somewhat easy to find. <br><br>
At any rate, I have a back log of personal projects still and I will endeavor to publicize them when I feel doing so adds value to our pool of knowledge. Now without further ado:<br><br>
The Akai MPC2000xl I purchased new in the spring of the year 2000 had lost function of the note variation slider. This appears to be, based on my perfunctory google search, a relatively common problem. Replacement parts are easy to find through branded supplier sites, but I'm a skinflint so when I happened upon a webpage that outlined opening up the slider and cleaning it out I naturally took that road first. <br><br>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjf9GSLO43r-yn9TA-Ao32C3tqKsVVpSXRthEtsAmoN459nu9sWGGUl_iwj6sLe1Lc39G19raSjdua1LRFotAogRwb3EWp5e6LBLipxWw5-RfdpByB9f4d8Z2TwcmThVxEJhwen9g/s1600/MPCsliderdirty.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="659" data-original-width="1000" height="211" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjf9GSLO43r-yn9TA-Ao32C3tqKsVVpSXRthEtsAmoN459nu9sWGGUl_iwj6sLe1Lc39G19raSjdua1LRFotAogRwb3EWp5e6LBLipxWw5-RfdpByB9f4d8Z2TwcmThVxEJhwen9g/s320/MPCsliderdirty.JPG" width="320" /></a></div>
Are there twigs in there?<br><br>
Full disclosure: my studio environment has at times been substandard in regards to environmental control. We're talking basements, uninsulated sheds, and a warehouse space in which the only source of heat was a tube amp and an engine block cooling off after my drive home from work. Swings in temperature and humidity are hard on gear, and the necessity of fixing stuff has delivered me to where I am today. Anyway, the slider contacts were indeed swamped with muck. A little isopropyl gently applied was in order...<br><br>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIMMWRnbys7A8kt2ph0R9JFNtAL2DY7caeOQVP_Y45c1hBuMvA7Oq2_PEDUNrg0k-G28QhAwrfeGwhMqdhHlU0gK8ww2BPyMbvonuqmCx86fNPzJMigQi8Un9f4VqI2a-uPrHJDQ/s1600/MPCslidercorrosion.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="665" data-original-width="1000" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIMMWRnbys7A8kt2ph0R9JFNtAL2DY7caeOQVP_Y45c1hBuMvA7Oq2_PEDUNrg0k-G28QhAwrfeGwhMqdhHlU0gK8ww2BPyMbvonuqmCx86fNPzJMigQi8Un9f4VqI2a-uPrHJDQ/s320/MPCslidercorrosion.JPG" width="320" /></a></div>
..ah. Well then. It's an easy task to clean metal; it's quite challenging to grow it back into shape. And no, bending the corroded tines of the wiper outward a little bit in order to regain contact proved fruitless. <br><br>
So, as I mentioned before, you can simply punch a couple keywords into a search engine and locate a specific replacement for this part with ease. I found them ranging from $10 to $15 USD before shipping, which, while far from outlandish did not strike me as the most effective solution. <br><br>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRorkRZG_DSktXKMhnYAn9GGSIEMrUkO1nMt42_qZXSNoWcwD7S0Qp3tzaJlZXHfhvioAdEaiYbdPurgNYhGg1XgJ5Z1XfIQiSEYcN-im539kG4ZcSfiYcIG-TkBrqpTMfnlpNLg/s1600/PS45M-1PD2FLR10KN.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="384" data-original-width="1000" height="123" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRorkRZG_DSktXKMhnYAn9GGSIEMrUkO1nMt42_qZXSNoWcwD7S0Qp3tzaJlZXHfhvioAdEaiYbdPurgNYhGg1XgJ5Z1XfIQiSEYcN-im539kG4ZcSfiYcIG-TkBrqpTMfnlpNLg/s320/PS45M-1PD2FLR10KN.JPG" width="320" /></a></div>
I regularly order parts from Mouser for RMA, so it stood to reason that by looking for the part in generic terms I could skip at least one generation of mark-up. The criteria is 10K linear dual gang 45mm throw with a particular PCB footprint. I found my match <a href="https://www.mouser.com/ProductDetail/BI-Technologies-TT-Electronics/PS45M-1PD2FLR10KN/?qs=sGAEpiMZZMtC25l1F4XBU9kor%2FbsW%2FEvauXilr62FXBbTdwbKD6WHw%3D%3D">here at Mouser</a> for $1.83 before shipping. <br><br>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6sS-YxIKw75MMeDH0dX_TYVaLX7FNkYFZbU7EAbg2tt_AWtOgjgd_9GYOKgAAfTMQ91riNvrTrx-vFWZoWdVTZLRJNMbQb3jWCXa-kGYlXeQNdkElu_12mbggQUo6NQeQI5QyWQ/s1600/MPCinterfacePCBslider.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6sS-YxIKw75MMeDH0dX_TYVaLX7FNkYFZbU7EAbg2tt_AWtOgjgd_9GYOKgAAfTMQ91riNvrTrx-vFWZoWdVTZLRJNMbQb3jWCXa-kGYlXeQNdkElu_12mbggQUo6NQeQI5QyWQ/s320/MPCinterfacePCBslider.JPG" width="320" height="213" data-original-width="1000" data-original-height="665" /></a></div>
Here's a PCB side shot indicating the solder joints that need to be removed for extraction. The blue pads are structural and two of the lower pads connect to nothing and can be ignored (at least in my machine). <br><br>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivpXUoYV8Tmfhtt829bBomQJ9CtKb2Y3N5XDXBuGbs-HJln-0aNkVaE9whS_rHwpls0ufnDiaExURRgu3h-_e8xNVMMrJ4zkRELxS2Q1izeqKZhBLqw7CA4HPVd4_IUH-c0cRbww/s1600/topsideremoved.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="673" data-original-width="1000" height="215" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivpXUoYV8Tmfhtt829bBomQJ9CtKb2Y3N5XDXBuGbs-HJln-0aNkVaE9whS_rHwpls0ufnDiaExURRgu3h-_e8xNVMMrJ4zkRELxS2Q1izeqKZhBLqw7CA4HPVd4_IUH-c0cRbww/s320/topsideremoved.JPG" width="320" /></a></div>
Removal of the failed component was a breeze with my iron and a plunger type solder sucker. <br><br>
Look at that! A single sided PCB with through hole wire jumpers.<br><br>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRftZF55COvcfEtQgwddqUzkQt_J3wAJpzM3mD2DvdsFBcZVTkq5US5Umph8_8Pa9Sch4uL3SasXTGfoQse0oe7z9bhiWGF9E_GhytOy95yjsJ4vQZbxLAfJdwLTlAWdo3mc1H0g/s1600/PS45M-1PD2FLR10KNmounted.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="665" data-original-width="1000" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRftZF55COvcfEtQgwddqUzkQt_J3wAJpzM3mD2DvdsFBcZVTkq5US5Umph8_8Pa9Sch4uL3SasXTGfoQse0oe7z9bhiWGF9E_GhytOy95yjsJ4vQZbxLAfJdwLTlAWdo3mc1H0g/s320/PS45M-1PD2FLR10KNmounted.JPG" width="320" /></a></div>
New part drops right in, and soldered right up.<br><br>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhC7R4C2rdfqWKWLHl8YXCdOoXNnFwf1K5QeowVjJLSrBRPCp_VTt21E9gXMh6G8humkUHgyVe23a6oYl1PKtYnSc1vU6bWitzBWmbnhul8qApc-B3bVy-OrFSxF4TYisx-Zwuefw/s1600/MPCslidernew.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="665" data-original-width="1000" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhC7R4C2rdfqWKWLHl8YXCdOoXNnFwf1K5QeowVjJLSrBRPCp_VTt21E9gXMh6G8humkUHgyVe23a6oYl1PKtYnSc1vU6bWitzBWmbnhul8qApc-B3bVy-OrFSxF4TYisx-Zwuefw/s320/MPCslidernew.JPG" width="320" /></a></div>
It's alive!<br><br>
I didn't go into tear down of the MPC because while I am guilty of not having looked it up, I'm ASSuming there are numerous excellent information stores you can find regarding that. I do need to qualify my fix with the following:<br><br>
THIS IS NOT A DEAD STOCK REPLACEMENT.<br><br>
Functionally my machine works again, but the slider I used A) will not accept the stock slider cap (I may drill my cap out to attain a fit, but this is risky because the shaft of the new slider is larger in both non-height dimensions and there is not a lot of material to work with) and arguably more important B) the new slider has a center detent.<br><br>
Since this is my machine I do not mind the center detent (in fact, I kind of like it) but I should note that at centered position my machine reads a +8 in the +/-120 range, so electrically it is not centered when physically centered. <br><br>
For those reasons I would recommend the OE parts for client based work, but I'm happy with my fix.
crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com0tag:blogger.com,1999:blog-33019505.post-75019721756651589002015-05-16T07:36:00.001-07:002015-05-16T07:36:08.011-07:00Monumental absence on the blog-front, my apologies. I like to have something of an orderly line of thinking in this format, and frankly it seems as if I've been ensconced in avalanches of R&D or convoluted puzzles to the point that settling on a single train of thought would be detrimental to the process. Since there has in fact been physical realization of something, I can just shut up and talk about that! Haha, thanks for understanding.
<p>
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<p>
Pictured above is the preliminary assembly of the first two sections of a three section noise generator. The initial prototype is essentially a lifted collector white noise section cascading into a low pass section which in turn feeds a malformed state variable filter (not yet stuffed, obviously). I can't really call it that, because while it began life as a state variable it became mangled. I'm not going to elaborate further, because with the second generation prototype that section is facing a deep revision. The sonic goal of stage 3 is a pop-corn type crackle with adjustable intensity, please stand by.
<p>
Let's fast forward the initial build and actually listen to it:
<p>
<iframe allowfullscreen="" frameborder="0" height="270" src="https://www.youtube.com/embed/fu0Uq8hcxJQ" width="480"></iframe>
<p>
Something of an acquired taste, perhaps. Seems also to have aggravated the youtube compression algorithms, I can provide a clean recording on request (but seriously, the second generation is shaping up to be improved, so why bother!)
<p>
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<p>
Guts! Nothing much more to add here. I have slapped a primitive voltage regulation into it because I built it with a spot on 9 volts supplied by my bench supply, and every single wall wart I tried once built made it go haywire. Here's the believed to be accurate schematic of the initial prototype:
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjETpsDteI2b9D4EKkgSu1Pi4-jubQt_XiJzucXuhS3YPvKV9e82J2ajhKy-rKf7knLNYWhAfcBdlJd7XEoDYIzY8eQwPZ_AnbcZXquZtE0-1QE_l7BaPOb-aELIc7i_6A3QXEcVQ/s1600/rev1crustacean.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjETpsDteI2b9D4EKkgSu1Pi4-jubQt_XiJzucXuhS3YPvKV9e82J2ajhKy-rKf7knLNYWhAfcBdlJd7XEoDYIzY8eQwPZ_AnbcZXquZtE0-1QE_l7BaPOb-aELIc7i_6A3QXEcVQ/s320/rev1crustacean.png" /></a></div>
<p>
If you're a lunatic and want to build one yourself, I would advise contacting me instead of going off this schematic - unless you want to be saddled with all the issues that are under resolution with the current build. Amongst design flaws that are resolved at this point: the loading down of the low passed crumble output control when other stages are turned up got cleaned up with a common collector buffer.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZHE-gPe55lK_UtbVFZdn1B1BslBWENv2Eb2nGdpOyObOJ0Ysh8gtiXDkaUxQBia-vVQT6wvzxi343LGQ7wX6_1nWghj3vVTe_Z4rYARmdgkKNAPGb2iTb6n-vAB-8TgCv_BDAVA/s1600/crustaceanV0-1comparison.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZHE-gPe55lK_UtbVFZdn1B1BslBWENv2Eb2nGdpOyObOJ0Ysh8gtiXDkaUxQBia-vVQT6wvzxi343LGQ7wX6_1nWghj3vVTe_Z4rYARmdgkKNAPGb2iTb6n-vAB-8TgCv_BDAVA/s320/crustaceanV0-1comparison.JPG" /></a></div>
<p>
Layout on the proto-board is also taking a more direct path.
<p>
With the exception of the initial noise source stages, I identified gain stages and buffers - then settled on a uniform configuration of values to simplify assembly. This created additional problems with the triac, but since the operating characteristics of each and every one seems different (I'm pulling from a really old bag, so it's anyone's guess if this is due to my circuit conditions or age/sloppy manufacturing tolerances) I needed to allow for calibration anyway. Now I can dial the triac up to the point where it's *not quite* stuttering and cutting out, which has improved the crumble of stage two substantially.
<p>
So there you have it, I may update on stage three once I get it sorted (lower right knob needs more travel/interaction), or we might take a look at something else. I'll try and touch base before another season goes by...
crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com16tag:blogger.com,1999:blog-33019505.post-989032953214854162015-02-13T20:00:00.002-08:002015-02-13T20:00:43.430-08:00<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjh6V20zU-U3QovQvgdsjsq1N8ZZ7E1rQlRCVcDCXWhf5672VMixZN_JiIFeDQi2NBg9RE46-orWJuOKBdiDfyISkcrrbkatSw8qsLh7u3ZVXcZ1CHuN8Z5yy3jMg1ELbyVmuSp6Q/s1600/Xray.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjh6V20zU-U3QovQvgdsjsq1N8ZZ7E1rQlRCVcDCXWhf5672VMixZN_JiIFeDQi2NBg9RE46-orWJuOKBdiDfyISkcrrbkatSw8qsLh7u3ZVXcZ1CHuN8Z5yy3jMg1ELbyVmuSp6Q/s320/Xray.png" /></a></div>
<p>
It made a beautiful sound when it hit.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com0tag:blogger.com,1999:blog-33019505.post-62825719937923827402014-12-16T17:24:00.000-08:002014-12-16T17:24:33.552-08:00After a long while (10+ years) of periodically checking for 2.75"/70mm throw sliders to fill the gaps on the <a href="http://crochambeau.blogspot.com/search/label/Langevin%20AM301">Langevin AM301</a>, I finally stumbled across an auction for unused Duncan Slidelines and decided to procure one for every channel.
<p>
Granted, these are 100K lin as opposed to 50K log, but this gives me an excuse to fumble around with changing the law via external resistor AND to finally dive into this unit.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4lXwxcd-NKP0ogWoj5G7CDVnw81IweUZ3U3gE6UDW9ARW55geZpE440z7SOnL-8Wgom22eR23oO2vYyaKfCMWcCqGfpn2Y0-7YMNoZFcNZr_UUggG1wT9OuJ6dS0Dk5p1fLZd1w/s1600/AMgutshot.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4lXwxcd-NKP0ogWoj5G7CDVnw81IweUZ3U3gE6UDW9ARW55geZpE440z7SOnL-8Wgom22eR23oO2vYyaKfCMWcCqGfpn2Y0-7YMNoZFcNZr_UUggG1wT9OuJ6dS0Dk5p1fLZd1w/s320/AMgutshot.JPG" /></a></div>
<p>
Off with its face!
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtn2WNe7DwUNeuTkqzlCUlVU1hus79rOuukWkCJtkOF1Z1LNEGnVWNqf-ArBDE-IBlHBnoT8s8zz9R__fHUI8mTY6Cap6i9vTPjjnJM-eDOkFBtydvaox4yRvb1ra1wGsqOe-igQ/s1600/loose-ends.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtn2WNe7DwUNeuTkqzlCUlVU1hus79rOuukWkCJtkOF1Z1LNEGnVWNqf-ArBDE-IBlHBnoT8s8zz9R__fHUI8mTY6Cap6i9vTPjjnJM-eDOkFBtydvaox4yRvb1ra1wGsqOe-igQ/s320/loose-ends.JPG" /></a></div>
<p>
This explains some of the non-functional channels, some others have fader assemblies that are breaking apart (not pictured, yet).
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitb3wyTb_DzUi3WtKLQ4GrCeu4aV8st1HfhwjK31JxtyUQv_9RhkUVPjhejc5XOAVYmwz-1o0r1AmK1CdccZYmpYYaMFhH072cUvXxxeBhIdX3ccoaMLevWVaA9tII0n7xf5RHdA/s1600/leaky-beaver.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitb3wyTb_DzUi3WtKLQ4GrCeu4aV8st1HfhwjK31JxtyUQv_9RhkUVPjhejc5XOAVYmwz-1o0r1AmK1CdccZYmpYYaMFhH072cUvXxxeBhIdX3ccoaMLevWVaA9tII0n7xf5RHdA/s320/leaky-beaver.JPG" /></a></div>
<p>
Better oust these old electrolytics while I'm at it.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZhcdxx4tAFClXHNi6Xi4znrZli-igBcRYaGc8IOPI4JtPBM2M0d7pZ6L6LexTySGlQ3qz8yQ3l9S9Hf21dw-KcujXXnyx8AQQ1X7vK1hJhZGss7WOhxzywbOJ7KCyVh50FLp_tQ/s1600/slideline50Ka.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZhcdxx4tAFClXHNi6Xi4znrZli-igBcRYaGc8IOPI4JtPBM2M0d7pZ6L6LexTySGlQ3qz8yQ3l9S9Hf21dw-KcujXXnyx8AQQ1X7vK1hJhZGss7WOhxzywbOJ7KCyVh50FLp_tQ/s320/slideline50Ka.JPG" /></a></div>
<p>
Here's a shot of the stock wiring.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQ46OtDya4b2lirD5nr34v_oSjGzl4N1Br-yu3IG-UCauG4qPxPcPPf61aM4AhTr733Gxynz6_aLYADs48YEHDwtEjel8nfCGjwMQvvsvC3afdHbybPkhzsAsDiecyC2SslS8wKQ/s1600/dual-gang.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQ46OtDya4b2lirD5nr34v_oSjGzl4N1Br-yu3IG-UCauG4qPxPcPPf61aM4AhTr733Gxynz6_aLYADs48YEHDwtEjel8nfCGjwMQvvsvC3afdHbybPkhzsAsDiecyC2SslS8wKQ/s320/dual-gang.JPG" /></a></div>
<p>
Here's someone's mod, I guess. Dual gang to unify two channels across one fader? It does explain why there has been an empty slot staring back at me as long as I have owned this thing. Mind you, I don't think this "fix" is still functional. Was it ever?
<p>
The stems on these faders are slightly smaller than the stock Slidelines, meaning I will be going with another sort of cap (I know I mentioned seeking some red Rollo looking caps last time). Onward & upward.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com0tag:blogger.com,1999:blog-33019505.post-87317060409795045102014-11-17T06:00:00.000-08:002014-11-17T06:00:07.251-08:00Here I am, working around the inherent constraints of SMT componentry for use in your garden variety free form "rat's nest" point to point build.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdByRCx54eYS7UUFO_H3zhs5DL2wLFCYA6fcDZ2CM_4Hsq6awP0nK1tTSPoQ58rk0NyKHUrC1EMxJO7GqOBSILereyYnRp0cCHOqCqkampDiCqBx0qIkMid5RM89eMODM1N3OyXA/s1600/legging.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdByRCx54eYS7UUFO_H3zhs5DL2wLFCYA6fcDZ2CM_4Hsq6awP0nK1tTSPoQ58rk0NyKHUrC1EMxJO7GqOBSILereyYnRp0cCHOqCqkampDiCqBx0qIkMid5RM89eMODM1N3OyXA/s320/legging.JPG" /></a></div>crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com1tag:blogger.com,1999:blog-33019505.post-45051441539098867002014-11-15T06:52:00.002-08:002014-11-15T06:52:56.989-08:00Found out what was rattling around in my old Pioneer SR-101, something sheared the top of a 6BM8.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0bTPKTQ1vKYPpGKN70Wkb36r84KIS8V_NS36m4USA0rpe_-Qy93IB3rY9MHAnB0kij8e6d9Dk1POkuEJYDRxaOQOl2r99oN1pAPxWa8LmE8H-kbDMfzXJiS2rwD07ATKw7dJtPg/s1600/Pioneer-SR101.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0bTPKTQ1vKYPpGKN70Wkb36r84KIS8V_NS36m4USA0rpe_-Qy93IB3rY9MHAnB0kij8e6d9Dk1POkuEJYDRxaOQOl2r99oN1pAPxWa8LmE8H-kbDMfzXJiS2rwD07ATKw7dJtPg/s320/Pioneer-SR101.JPG" /></a></div>
<p>
More inspiration to stop gigging the antiques.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com0tag:blogger.com,1999:blog-33019505.post-42022914393172544562014-11-08T06:57:00.002-08:002014-11-08T07:01:58.796-08:00Whew! So I have to remind myself how HTML works every time I post. Clearly I'm not being active enough, but rest assured, the wheels have been turning in the background. I've got a couple "filler" angles I can exploit, and while I detest the notion of coughing up fluff, if I have to stop and think about how to break a new paragraph something has to give.
<p>
Anyway, been tearing down some organs lately and have wound up (literally) wading through piles of interesting parts.
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifxL1Qu846Rw8Uho67yODLTRmWtKX5EbAMTVw6bdRNSYQI1V8LH7saNJVqubEU5bRPJUxjvNMVPJ-RraK8l0eO9_hdY4M6tUQX10C7q0AaT5UQ1JN9mj4Cn9B57mRlRtEhTmCNmA/s1600/clave-off.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifxL1Qu846Rw8Uho67yODLTRmWtKX5EbAMTVw6bdRNSYQI1V8LH7saNJVqubEU5bRPJUxjvNMVPJ-RraK8l0eO9_hdY4M6tUQX10C7q0AaT5UQ1JN9mj4Cn9B57mRlRtEhTmCNmA/s320/clave-off.JPG" /></a></div>
<p>
Low tech switch design. Left depicts an open condition, right depicts an operational failure. Easy fix, of course; sort of like brushing the bugs out of an early computer.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrCMb0u-KgbJdOnUBSw2i2iriBwUkMkUznmJ2ldR6m3WTGz9vXHSP5KpfFfRSpbdehgpycpyDh0VaO3NKvN4vP3CmryjyPYZB7OmbhB2cYfyVuvMkJP9GbkskY8p6I92Tp_vbFAw/s1600/clave-closed.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrCMb0u-KgbJdOnUBSw2i2iriBwUkMkUznmJ2ldR6m3WTGz9vXHSP5KpfFfRSpbdehgpycpyDh0VaO3NKvN4vP3CmryjyPYZB7OmbhB2cYfyVuvMkJP9GbkskY8p6I92Tp_vbFAw/s320/clave-closed.JPG" /></a></div>
<p>
Lots of gritty potential.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwk7yUuyjxxKMaZqAOwkB_0XRclP7P3Swxc8B9Fc1Ud9Xup13njg24VEPbCTkMpf9c12Pp75YoX0QrAHvkNItEXY1q0iJqaV2wi-tBQoBp_yonusQylXb_rI1WWabNyHmWeRQsUw/s1600/gulbransen-drum.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwk7yUuyjxxKMaZqAOwkB_0XRclP7P3Swxc8B9Fc1Ud9Xup13njg24VEPbCTkMpf9c12Pp75YoX0QrAHvkNItEXY1q0iJqaV2wi-tBQoBp_yonusQylXb_rI1WWabNyHmWeRQsUw/s320/gulbransen-drum.JPG" /></a></div>
<p>
More 1970s analog drum machine guts!
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNtDZpCFFjPoD03RYsF7rDRY6sI9Hv0P-JH9DaC3QPZvBTgOwpjFwJ9rOQqy_ewngeMgLP8cBei-2ZJiMDTUbmPUDi90yTiO5uVHi3kTe-MAraygOaNog38wEEwWF8Gv7HYHza3A/s1600/percussion-stack.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNtDZpCFFjPoD03RYsF7rDRY6sI9Hv0P-JH9DaC3QPZvBTgOwpjFwJ9rOQqy_ewngeMgLP8cBei-2ZJiMDTUbmPUDi90yTiO5uVHi3kTe-MAraygOaNog38wEEwWF8Gv7HYHza3A/s320/percussion-stack.JPG" /></a></div>
<p>
Daughterboard sounds as follows: #5 = BASS, #3 = SNARE, #4 = CLAVE, #6 = CONGA. Presumably the BRUSH, CYMBAL & SANDBLOCK (?) are handled on the inductor laden side of the main board. I'm a bit apprehensive about snare being built around the same circuit topology as bass & conga (the daughterboards are identical PCBs stuffed with different values), but whatever the sounds I have to thank the good people at Gulbransen for clearly labelling voltage supply points, etc.
<p>
I guess I should mention that the lowest daughterboard in that picture is a signal amplifier, not a one shot oscillator. I'm too fond of individual outputs to leave that section alone, but I'm certain it will see use in some capacity.
<p>
Once I scrape the dust off this it'll be a snap to try out.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com1tag:blogger.com,1999:blog-33019505.post-56737812754916941392014-10-20T06:23:00.001-07:002014-10-20T06:23:43.990-07:00<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMPFzSwfP04wCeZc2N4XOLth-Nz7iTpkib9E9b6W-9aFUIlcRuNmURG3MzXTi5s4sLlAGHLnAN4MacjlCIKexGuYqT7o-Co7_7xKPfuAOS2nxyE4O9iwVPueymyjTtxEBerNxHoA/s1600/bent-pin.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMPFzSwfP04wCeZc2N4XOLth-Nz7iTpkib9E9b6W-9aFUIlcRuNmURG3MzXTi5s4sLlAGHLnAN4MacjlCIKexGuYqT7o-Co7_7xKPfuAOS2nxyE4O9iwVPueymyjTtxEBerNxHoA/s320/bent-pin.JPG" /></a></div>
I'm sure it passed functional test..crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com0tag:blogger.com,1999:blog-33019505.post-49439918401277955292014-08-03T09:02:00.000-07:002014-08-03T09:02:42.501-07:00Playing at an outdoor fest next weekend and have wound up supplying the low frequency component of the PA system, which will be run by someone else. The last time the bins were cut loose outdoors <a href="http://crochambeau.blogspot.com/2011/08/more-broken-speakers-pushing-into.html">this happened</a>. Fortunately a while back I wound up with a PCB for a stereo 3 way crossover that appears to be based on the Linkwitz Riley circuit, so I decided to build it with crossover points of 40 and 120 Hz.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaRJmkGcNgn8a2qTzHibOxdrLGwAvdlXLweKuxJsnfYqELEO2b_TJXKdAUoP7gSEaZODGi73MnlLVljQT5jg2F3BuGhkfhyphenhyphenHhqS9IOA7NTa5ANqBLIRDlGMxYM-XuonY34jtnmUg/s1600/CSS3way.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaRJmkGcNgn8a2qTzHibOxdrLGwAvdlXLweKuxJsnfYqELEO2b_TJXKdAUoP7gSEaZODGi73MnlLVljQT5jg2F3BuGhkfhyphenhyphenHhqS9IOA7NTa5ANqBLIRDlGMxYM-XuonY34jtnmUg/s320/CSS3way.JPG" /></a></div>
<p>
Of course, it would appear as if the capacitor type I had on hand with sufficient quantity (for matching) and value (1uf, to maintain a reasonable range for resistance) is a touch larger than original design...
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8VcGV5THTTohGhvywtdeikSEXel4F0wbGG2b4vwupoiDyinBtNgInSF79UsiXvuPX0xTBvrGXhD36pKIeLBH0pNTLRTBUR4nFF9JYM1FZnRz9RpwhASxyg4NyDJRtMI49JXt9ig/s1600/overlap.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8VcGV5THTTohGhvywtdeikSEXel4F0wbGG2b4vwupoiDyinBtNgInSF79UsiXvuPX0xTBvrGXhD36pKIeLBH0pNTLRTBUR4nFF9JYM1FZnRz9RpwhASxyg4NyDJRtMI49JXt9ig/s320/overlap.JPG" /></a></div>
<p>
...which led to something of a congested stuff.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilH5vJ7LO0s_p5rEjdlpDgnRGvPYn7-stwoY-PW7YuVXpijKCU1YavAjQ-PRZ9bBbtseT7OXnXECg_Ex6iElsafOfVNH4FVI7aFMJEPhWSuiEXJlBMys4H0kWVDMNitGNzZ0oRhA/s1600/WIMAforest.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilH5vJ7LO0s_p5rEjdlpDgnRGvPYn7-stwoY-PW7YuVXpijKCU1YavAjQ-PRZ9bBbtseT7OXnXECg_Ex6iElsafOfVNH4FVI7aFMJEPhWSuiEXJlBMys4H0kWVDMNitGNzZ0oRhA/s320/WIMAforest.JPG" /></a></div>
<p>
I figure I can use the low range of <40 Hz to throw away subsonics (and audible stuff below the horn loading of my bass bins, sorry) in a live setting, and route that to CV stuff in a studio. Not saying I'll opt to shave deep lows in a recording atmosphere, don't be silly, it's just nice to have the ability to prune a branch in that manner.
<p>
Of course, if I REALLY like it, I may go crazy and build one with DOAs.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com2tag:blogger.com,1999:blog-33019505.post-20213715525572445512014-07-20T12:39:00.001-07:002014-07-20T12:43:54.340-07:00It began with a feeling of dissatisfaction with my over all sound quality whenever I packed up some gear to play a live show. At this point, it's probably best if I expand on what I mean by quality: it's not a term that I am using to describe low noise, astronomical bandwidth, and remarkably low distortion figures. I have enough of that shit with the mass produced junk that birthed these complaints to begin with.
<p>
I should also point out, to the internet traveller that may be reading this as result of information hunter/gatherer forays (as opposed to the handful of freaks that know me), that in my application of these tools I am not striving for faithful reproduction, vintage tone or many other aspects in the array of audio qualities that drive gear obsessed frenzies of human endeavour. What follows is decidedly NOT a page to follow if you are hoping to recreate a nuance to fit into useful applications of gear in a client based environment, or where there may be a self professed audiophile or two creeping around the woodwork. There is no deeply entrenched philosophy driving this beyond my trying to use only what I had on hand
<p>
I also realize that from an electrical engineer standpoint the following may constitute a load of bollocks the likes of which all upstanding individuals in the industry have been striving to wrench into non-existence for about as many decades as mathematics have been applied to the craft, which, unless I am mistaken - is all of them. I realize my methods herein are laughable, and I assure anyone that were I not building this for myself I would not opt in on the sort of short cut that might make you cringe. Unless of course I was directed to do so.
<p>
So yeah, that preamble amounts to a wordy "yeah, yeah, yeah, I know" to the quantity of errors that I know follows, and furthermore to the quantity I didn't catch. Enjoy.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGc0KO3EDou0t1rDwbfjWOToquVQaXAxDj_0GwRB-RMzDahMUQWEkPYLAf9Pqo9Q_gfRf_6ykNkV0wJgV7y4MIfTJUw5rmva0l3cviFU6_svdDlaEspxfWb6f3oKMy5o8mxaB5Ww/s1600/proto918.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGc0KO3EDou0t1rDwbfjWOToquVQaXAxDj_0GwRB-RMzDahMUQWEkPYLAf9Pqo9Q_gfRf_6ykNkV0wJgV7y4MIfTJUw5rmva0l3cviFU6_svdDlaEspxfWb6f3oKMy5o8mxaB5Ww/s320/proto918.JPG" /></a></div>
<p>
With the Autogram AC-8 that fronts my studio as a reference to the sound quality that got me spoiled to begin with, I decided to emulate the largely passive transformer coupled mixing network feeding discrete operational amplifiers. So this build will play out like a mystery, start at the end and work my way back. I selected the <a href="http://www.sg-acoustics.ch/analogue_audio/discrete_opamps/pdf/918_documentation.pdf">Jensen 918</a> as the platform I would build from, mainly because it was the first one I happened across that contained a sufficient amount of documentation.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYFGoWiVC9qlew6QHEEkmOnzvW1uO4QjtrRMIRI6StO65Q4xHf6d7xczC3naAe16rpqDqQxO4QxN3PduzkzX3-KD3WyGRVkIKim_XvVL69zGrNfMh-fPcyQt5ea7JM7eLptOkkZw/s1600/918topside.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYFGoWiVC9qlew6QHEEkmOnzvW1uO4QjtrRMIRI6StO65Q4xHf6d7xczC3naAe16rpqDqQxO4QxN3PduzkzX3-KD3WyGRVkIKim_XvVL69zGrNfMh-fPcyQt5ea7JM7eLptOkkZw/s320/918topside.JPG" /></a></div>
<p>
Clearly depicted here is a complete disregard for thermal coupling, though I did strive to keep signal flow as "direct path" as I was able.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-l0qxwDoSRP5xdbu8ooIuOfvjsiMNNYWlZ2ZxWmPmOOrlFRMlSx3e4SE44k8T4LGm_53g0UPgAzfF5IMWbqm75_ZP3FY3ZDeUZ2ibgR0hDJQ8uoOdEyDYNlcqZ4Ztmt8a4xgBPQ/s1600/1Ksemistuffed918.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-l0qxwDoSRP5xdbu8ooIuOfvjsiMNNYWlZ2ZxWmPmOOrlFRMlSx3e4SE44k8T4LGm_53g0UPgAzfF5IMWbqm75_ZP3FY3ZDeUZ2ibgR0hDJQ8uoOdEyDYNlcqZ4Ztmt8a4xgBPQ/s320/1Ksemistuffed918.JPG" /></a></div>
<p>
Of course, without supporting circuitry, the op-amp was somewhat underwhelming. Thankfully the documentation linked above addresses everything you need to build it Note, if you want to use a +/- 24 volt supply - you'll see reference to some value juggling on a page that doesn't seem to exist. I've had no trouble running mine on +/- 24 volts having swapped out the 27K with 47K.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJub_ZTbnqAqNREEXIeiVS9wlzlmkemrqNa73XgDBWwiFK7s9x5ULdV5Pymbs0pUeDexcNHw40xzTCOa_wFXwpxe_kc_4CaCSDb-EMol_MPdzUEcCfna-LW0TEvaleqfSJB-QSPg/s1600/918pair.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJub_ZTbnqAqNREEXIeiVS9wlzlmkemrqNa73XgDBWwiFK7s9x5ULdV5Pymbs0pUeDexcNHw40xzTCOa_wFXwpxe_kc_4CaCSDb-EMol_MPdzUEcCfna-LW0TEvaleqfSJB-QSPg/s320/918pair.JPG" /></a></div>
<p>
I wound up slapping blocking caps on input and output because either I built it wrong, or it is designed to supply +22 volts on output, and +10 on input. If I built it wrong, I don't want to be right. Coupling caps sorted out the DC element out of respect for neighbouring stages, and the output leg with the larger carbon comp 33 ohm load is slated to feed a pair of output transformers (with 2N3904/6 complimentary pair, yes, I realize heavier outputs would do more lifting.. performs just fine for my application. Distortion capability on this board is delightful, I trimmed it up to the point at which it was clearly going into class C, then scientifically dialed it back to the point at which the audio filled out.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnGrpVurdbNbkXl7rHEPw6FiEcmfEiDAEdSxEvkVpxyaqS62tyOmgrlQrIEmm-9anquAteRgvD7FwYkq16lpc8HHpzz1DB5kDrrPiHtKkg4FjtASNhrgxiIWUdHz680n7h71nSxQ/s1600/8chan.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnGrpVurdbNbkXl7rHEPw6FiEcmfEiDAEdSxEvkVpxyaqS62tyOmgrlQrIEmm-9anquAteRgvD7FwYkq16lpc8HHpzz1DB5kDrrPiHtKkg4FjtASNhrgxiIWUdHz680n7h71nSxQ/s320/8chan.JPG" /></a></div>
<p>
So, haphazard summing section in hand, I needed to sort my inputs. The aforementioned Autogram is a stereo in/out desk, and as such I have been somewhat hindered in the ability to pan mono signals without the introduction of another mixer - which paves the way back to sentence one.
<p>
GOTO 10
<p>
I don't really recall even giving the idea of a passive front end with pan any thought at all. So, right out of the gate it had to be active, and in line with my build so far it had to be devoid of integrated circuits. Enter the schematic for a Neve BA284, I worked up a layout that could fit eight onto a single proto-board.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhY00BxY6cHBw5QkvU9mdyXKlVAnUBu8NefhVpyMADlxh-5WRqF7GiIbg9pA3dH40oMoAeznqcATjFRmWnnHgKimR9bjt0KTHUsycOhDHF78ICJIPXLu3qyaDuDGz19bdNcboHYLw/s1600/channel-profile.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhY00BxY6cHBw5QkvU9mdyXKlVAnUBu8NefhVpyMADlxh-5WRqF7GiIbg9pA3dH40oMoAeznqcATjFRmWnnHgKimR9bjt0KTHUsycOhDHF78ICJIPXLu3qyaDuDGz19bdNcboHYLw/s320/channel-profile.JPG" /></a></div>
<p>
I knew it was going to be tight, so everything went on in upright configuration..
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXaAQnaiiye786C5FduhnQ1876grE1-AgJHdAB1X4qxNbPwTnXupS2v8Y4aNNzb2rgMS9v-gyFZkktdrzTxN6BR4cWCDzrHO2vlwmc4k-C_1iZ0oyY97Y4J06LK-Xr8PiFi5-t6g/s1600/backside-mockup.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXaAQnaiiye786C5FduhnQ1876grE1-AgJHdAB1X4qxNbPwTnXupS2v8Y4aNNzb2rgMS9v-gyFZkktdrzTxN6BR4cWCDzrHO2vlwmc4k-C_1iZ0oyY97Y4J06LK-Xr8PiFi5-t6g/s320/backside-mockup.JPG" /></a></div>
<p>
..and when I was squeezed off the front, I resorted to stuffing from the back.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhg8XUL3-Auj9RgYl9Kj3fBNn2qTHaZCYpPvWRj5wd2FfAUAtQA4abGPdHzZ6ZITRbGcObvlowsCDMZLYeXdZM4iDeUU9j6mLfopFB6zno-S9CnQKUvOtMTD-14tBZOVhZE4jZrfg/s1600/input-channel-detail-1.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhg8XUL3-Auj9RgYl9Kj3fBNn2qTHaZCYpPvWRj5wd2FfAUAtQA4abGPdHzZ6ZITRbGcObvlowsCDMZLYeXdZM4iDeUU9j6mLfopFB6zno-S9CnQKUvOtMTD-14tBZOVhZE4jZrfg/s320/input-channel-detail-1.JPG" /></a></div>
<p>
Everything is still pretty reasonable and accessible, though I am going to have to tie wires into the floating pigtails in the middle section.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNXFY-yzkJFwgoFFr8PNH2Pg0a6fIhNygvZpDONR7FpmrZaFnndG2FaKVz9I_jdqVuq1LWnsSlKKT0qEG8cXYrb8A54ggjiBnVXuOVI4Wdr1wsYYfXVap8eNp3bnY006FhKdwMNw/s1600/8channel-tant.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNXFY-yzkJFwgoFFr8PNH2Pg0a6fIhNygvZpDONR7FpmrZaFnndG2FaKVz9I_jdqVuq1LWnsSlKKT0qEG8cXYrb8A54ggjiBnVXuOVI4Wdr1wsYYfXVap8eNp3bnY006FhKdwMNw/s320/8channel-tant.JPG" /></a></div>
<p>
Same level of progress, just another angle to illustrate my complete disregard for long lead insulation.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVO7690fSob_r16HYe1AYAbpDjvzkAJ8iQebd55S2-kfwJW5tYt7dRXslPR4bKKPZ0cba2l70jUo6V64txo2daQEMfteroOHJ__SzLS0I68zZPV-UdvwjXNlL9J-R6QIHxm4ZGwQ/s1600/incomplete8channel-summing.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVO7690fSob_r16HYe1AYAbpDjvzkAJ8iQebd55S2-kfwJW5tYt7dRXslPR4bKKPZ0cba2l70jUo6V64txo2daQEMfteroOHJ__SzLS0I68zZPV-UdvwjXNlL9J-R6QIHxm4ZGwQ/s320/incomplete8channel-summing.JPG" /></a></div>
<p>
A moment contemplating the two, wondering what I've gotten myself into.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjU28FPSulaKH-HFU0OhSKVeSLPR5HO9f5L_1IIvjxEBazyrC4Ro01BtMoKbNHAQcV7p32inQhPsMrQKuBYA6on6pQBIm2f9opwhkdrO_d4QKUOJBwJWGqrr5C7W9n4dAHb3nsp_g/s1600/input-channel-detail-2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjU28FPSulaKH-HFU0OhSKVeSLPR5HO9f5L_1IIvjxEBazyrC4Ro01BtMoKbNHAQcV7p32inQhPsMrQKuBYA6on6pQBIm2f9opwhkdrO_d4QKUOJBwJWGqrr5C7W9n4dAHb3nsp_g/s320/input-channel-detail-2.JPG" /></a></div>
<p>
Who needs modern compact electrolytics when big fat dipped tantalums are on hand? Wanna argue capacitor merits? I already know the tantalum is WIDELY poo-pooed by the golden ear community (GOTO 20). Again, my build, besides, I've heard other audio egg heads remark that early Neve sound comes partly from the use of tantalum, and that his application of them biased the capacitor such that many of the distortion characteristics that many find distasteful were designed out.
<p>
Whatever, I'm regurgitating stuff I've read on the internet. I don't know. Hell, I don't even know if the schematic I used is in fact a Neve as it is passed as. Could be a heat control for a toaster oven for all I know. The big orange caps are pretty, justification complete.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgh7VB6YHGDpa2I6bev591ruTtiXLTRk95g0zd-z6wOe0aZysfKmtKBek5amf0YCweHjplpLqgO9cLS__4MTjIMT38yRsRHbyCG1kJ7LWJZH98lXMVW5-1w0s1mlP0hEaKavDFsqg/s1600/channel-block.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgh7VB6YHGDpa2I6bev591ruTtiXLTRk95g0zd-z6wOe0aZysfKmtKBek5amf0YCweHjplpLqgO9cLS__4MTjIMT38yRsRHbyCG1kJ7LWJZH98lXMVW5-1w0s1mlP0hEaKavDFsqg/s320/channel-block.JPG" /></a></div>
<p>
Gee, maybe I should have tested this thing before going this far?
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUg7v9q_ZEU9jOOyDHyXvIVl4elu6wHWJkzWP3h-FvKQ-qFS0KPB6_E5oEj__x06_ZwJoC4a3CDWap8ijcyhu-fq_QGmYrpvKq1YM3mnvHaH-10GZqJo2f95ETWUJTMivQrPPKlQ/s1600/channel-under.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUg7v9q_ZEU9jOOyDHyXvIVl4elu6wHWJkzWP3h-FvKQ-qFS0KPB6_E5oEj__x06_ZwJoC4a3CDWap8ijcyhu-fq_QGmYrpvKq1YM3mnvHaH-10GZqJo2f95ETWUJTMivQrPPKlQ/s320/channel-under.JPG" /></a></div>
<p>
Re-work will not be a breeze.
<p>
So, once wired up for test here's what happened: Channel 1-3 passed audio, 4 was dead (bad mid 1973 tant cap on input - replaced) 5-6 passed audio, 7 was dead (solder bridge, easy fix) and 8 was very low volume (less critical solder bridge).
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJT0cGbAmbxgbKvjRshAs7qTN8Dhbn95tXKlKhyphenhyphenI9EN9NiXb1ceQoQWRoYD2IVYu5AxlEYqA-4A1JLuJZQ8JgMhDUxtzcJ4bskXOtmw8tlta16OPjoK2Nms0MFt3yEqOdqItEjUg/s1600/routing.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJT0cGbAmbxgbKvjRshAs7qTN8Dhbn95tXKlKhyphenhyphenI9EN9NiXb1ceQoQWRoYD2IVYu5AxlEYqA-4A1JLuJZQ8JgMhDUxtzcJ4bskXOtmw8tlta16OPjoK2Nms0MFt3yEqOdqItEjUg/s320/routing.JPG" /></a></div>
<p>
On to connecting the two. Currently the 8 channel block feeds 1:1 transformers, which feed a single pot passive pan control which feeds a dual gang audio taper volume control feeding the stereo buss to 918 opamps.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEih_PCM3vPj4q5B61ETb8pwGPvK0dn8h5AiyMNqp2nXb_RTWzQl54Kzpf0P2OAZj1upNsBR1Bk9cUzEMlf6iHU6gVfOhG3TBIt4ohDTLcsraYP21uOE42eCa9E4anOplJvO8yenag/s1600/stereo-buss.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEih_PCM3vPj4q5B61ETb8pwGPvK0dn8h5AiyMNqp2nXb_RTWzQl54Kzpf0P2OAZj1upNsBR1Bk9cUzEMlf6iHU6gVfOhG3TBIt4ohDTLcsraYP21uOE42eCa9E4anOplJvO8yenag/s320/stereo-buss.JPG" /></a></div>
<p>
More blatant disregard for insulation.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4fTldhdqhJIoY2fHKPg2BNWS0gCA_Zj95gH-T-ek-ZExFyhZVwOJi6BrxmLe1EWYzLizXDFTbSYbgw0Jg-WH50-b9LfETtCwVeHSOzZ42ubQE5SocGIgGForhlHtb5AK_3u-_iQ/s1600/buss-closeup.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4fTldhdqhJIoY2fHKPg2BNWS0gCA_Zj95gH-T-ek-ZExFyhZVwOJi6BrxmLe1EWYzLizXDFTbSYbgw0Jg-WH50-b9LfETtCwVeHSOzZ42ubQE5SocGIgGForhlHtb5AK_3u-_iQ/s320/buss-closeup.JPG" /></a></div>
<p>
HANGING FREE, READY TO SHORT.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiawb4-m4M-jX_PE5MiK4sNUlSmAaRrUY5fuy0qgA_dLsy5aW_VCmHneMTp-5iL3STMDuvXpEp8tbBrA-b8l0swHIqdkQ-6HmwyEQmBJWrUOnu6jNN590tEj6a6enUEMIppudxfhw/s1600/input-block.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiawb4-m4M-jX_PE5MiK4sNUlSmAaRrUY5fuy0qgA_dLsy5aW_VCmHneMTp-5iL3STMDuvXpEp8tbBrA-b8l0swHIqdkQ-6HmwyEQmBJWrUOnu6jNN590tEj6a6enUEMIppudxfhw/s320/input-block.JPG" /></a></div>
<p>
Input block in, those ugly holes will be direct outs from the inverting output section built into the BA284 clones (hahaha, they are as much a clone of the BA284 as Frankenstein's creature is a clone of a human being, but I digress). Fun fact, the jack connected to the blue wire is an open frame TT connector, it provided me with a little more first hand experience in reworking this free form construction. A lot easier than I had expected.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjwklk9Ux84t8lYWrZK93ratldAE8m7kkC3BYug9R5fX2ekiLErul2XvTpRGVqJXPn424hElhPuuXP9geS3XvPyBWt-Biprvh53xH3vd_K1v1Xi_V2iloYeEJkds5ZXc4ENHaVgg/s1600/buss-connection.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjwklk9Ux84t8lYWrZK93ratldAE8m7kkC3BYug9R5fX2ekiLErul2XvTpRGVqJXPn424hElhPuuXP9geS3XvPyBWt-Biprvh53xH3vd_K1v1Xi_V2iloYeEJkds5ZXc4ENHaVgg/s320/buss-connection.JPG" /></a></div>
<p>
Wire tie in about to be squished, then soldered.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3p1yCPpTYIsrBVxIHBUHZ32ep94915FfpDaKdYfdH9KP_8tTAXLf23LmkPsnhcJvylGIGOT-qfzJqI9-SQKhhOuTDCpnLhBWdgmaVkORejLTcaRlYP2OhaiNb2h4_-EPk5IfV_g/s1600/top-shell.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3p1yCPpTYIsrBVxIHBUHZ32ep94915FfpDaKdYfdH9KP_8tTAXLf23LmkPsnhcJvylGIGOT-qfzJqI9-SQKhhOuTDCpnLhBWdgmaVkORejLTcaRlYP2OhaiNb2h4_-EPk5IfV_g/s320/top-shell.JPG" /></a></div>
<p>
Of course, at this point I'm working against the fact that I've got a show later in the day, and I would really like to use this thing. Top shell, current function largely wired.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh45ViO4NEX0A0eYtY_NS9xufWrjxiOhQ3uq6oucLWpXZ0RbJ2rTtfcmlWD2lU6ziF-q_NysHRi6dpRNMc9NEzFWMYJ732HxvVWU3PZ87Q4yUn32dtuE16WVOSyUSpFNZf0xlEmSg/s1600/baseplate.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh45ViO4NEX0A0eYtY_NS9xufWrjxiOhQ3uq6oucLWpXZ0RbJ2rTtfcmlWD2lU6ziF-q_NysHRi6dpRNMc9NEzFWMYJ732HxvVWU3PZ87Q4yUn32dtuE16WVOSyUSpFNZf0xlEmSg/s320/baseplate.JPG" /></a></div>
<p>
Baseplate, same.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkhAsbo0zkyunU4pwK1ThTnNPZKzwx5_wXKiBRp0y5eIrdTW5AcCm0XdwQkyN6M3S6DsmZf3o2BZBhN8Xp1ch7Gdc3i7Nk0Gh9eV5JMlGOs8KtLYEwEljm-IeDyIdAHd1vRfu6ww/s1600/connected-halves.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkhAsbo0zkyunU4pwK1ThTnNPZKzwx5_wXKiBRp0y5eIrdTW5AcCm0XdwQkyN6M3S6DsmZf3o2BZBhN8Xp1ch7Gdc3i7Nk0Gh9eV5JMlGOs8KtLYEwEljm-IeDyIdAHd1vRfu6ww/s320/connected-halves.JPG" /></a></div>
<p>
Quick connects and screw terminals allow for ease of disassembly.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgS640T5Z79hyiw2ij6V7AA_tZC4d5di3ne-SBQDh23B9D0jpaIK0X5y-8VX8Ur3q4e8gNMrEUAPuEmFnELG2uBH1a740-Up8gSu05k0SzWCdNfknXRtqiOBSs3Spz5QE9N3cnozA/s1600/volume-konbs.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgS640T5Z79hyiw2ij6V7AA_tZC4d5di3ne-SBQDh23B9D0jpaIK0X5y-8VX8Ur3q4e8gNMrEUAPuEmFnELG2uBH1a740-Up8gSu05k0SzWCdNfknXRtqiOBSs3Spz5QE9N3cnozA/s320/volume-konbs.JPG" /></a></div>
<p>
It worked fine. Only the fundamental functions are installed right now, but everything goes together like legos and inserting future sections will not require anything too extreme. Current duration of work so far: July 3-19. crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com1tag:blogger.com,1999:blog-33019505.post-81684780275858277042014-06-13T05:34:00.000-07:002014-06-13T05:35:38.160-07:00Happy 13th of Friday.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgS-KpqTJa3OjJ63_VE4R8c9sCn2EDosFEcigT3nU50UXtfowk26H5Y9xHQt6rgR7XQEx2qls4v4zGl9sKCNJutMe1AT_3vp3-q_L_Q4MOPAm4G7GTcJtI7fly-OOGouD4to0lwyg/s1600/6CA7bbq.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgS-KpqTJa3OjJ63_VE4R8c9sCn2EDosFEcigT3nU50UXtfowk26H5Y9xHQt6rgR7XQEx2qls4v4zGl9sKCNJutMe1AT_3vp3-q_L_Q4MOPAm4G7GTcJtI7fly-OOGouD4to0lwyg/s320/6CA7bbq.JPG" /></a></div>
<p>
This pair of Matsushita 6CA7 had made it all the way through sound check, and we were about to begin before the amplifier cut out and started stinking up the place.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUJ49Nqqnt749fhNBCHp-HJEA9WKVA0FyIKD-42TmRtPseSOxScmk6UzdCJ1ld0o8-AVskuNQXcloemLX6CUjIJ1sqJg9Rz5kFWxkQ0lg0N3P4iuIw6ckZ3T36bvMhASPIpnOjTQ/s1600/480ohms.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUJ49Nqqnt749fhNBCHp-HJEA9WKVA0FyIKD-42TmRtPseSOxScmk6UzdCJ1ld0o8-AVskuNQXcloemLX6CUjIJ1sqJg9Rz5kFWxkQ0lg0N3P4iuIw6ckZ3T36bvMhASPIpnOjTQ/s320/480ohms.JPG" /></a></div>
<p>
Carbon path through this former screen grid resistor now sits at ~60 ohms.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com2tag:blogger.com,1999:blog-33019505.post-84528799339223454252014-04-13T23:01:00.000-07:002014-04-13T23:01:00.288-07:00Picked up a couple Turner 500 microphones with native four pin Cannon/XLR plug and noticed an ALARMING LACK OF INFORMATION ON THE INTERNET in regards to refitting these with modern connectors. Tons of data regarding the HAM radio OEM stuff, but hardly a whisper in terms of studio quality stuff Turner churned out before their unfortunate demise.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGUKguq7PAOEQBFx9IKVgXNnO5dBnNafLuduSEHo6A52pbqOAwVkN9oq-Njb2TPhGXsCmOCdGCFqKKf1KMBIsLSMefhZOZgzmDmzWvG0OD7EtC0joEHnPC1v1wFNXy5JUksaAJKw/s1600/Turner-500.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGUKguq7PAOEQBFx9IKVgXNnO5dBnNafLuduSEHo6A52pbqOAwVkN9oq-Njb2TPhGXsCmOCdGCFqKKf1KMBIsLSMefhZOZgzmDmzWvG0OD7EtC0joEHnPC1v1wFNXy5JUksaAJKw/s320/Turner-500.JPG" /></a></div>
<p>
The original design is actually pretty cool. You have a case ground (black) a high impedance (blue) and a transformer coupled low impedance pair (orange/yellow), so you could cable select impedance. Reminds me of the old SM-57 transformer bypass mod, just so happens to be BUILT IN <i>and</i> optional on these.
<p>
That said, sourcing the 4 pin connectors for it now is something of a nuisance, and I want to reach for the low-Z mode anyway, so what you're about to see is an easily reversible disconnect of the high impedance (pre transformer) circuit.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4NqXB8aeb1x_9URTrgLda5_b61C0v0j5sFw1gP8CUys4O5xYe89z_1nUohrD-JlpQ1yqAGQEXbbrbQrzGfk9bFn7wA269hShk4bEOzDiyqfM1h2qhbxUXa-nEz7tv54IfPyMi8Q/s1600/3vs4.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4NqXB8aeb1x_9URTrgLda5_b61C0v0j5sFw1gP8CUys4O5xYe89z_1nUohrD-JlpQ1yqAGQEXbbrbQrzGfk9bFn7wA269hShk4bEOzDiyqfM1h2qhbxUXa-nEz7tv54IfPyMi8Q/s320/3vs4.JPG" /></a></div>
<p>
Form factor is identical, I happened to have a couple three pin Cannon male inserts lying around, which turned this into a full "bolt on" mod.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrtDuTKsAtCO09fYX5FbnEc2dF2locysScTLHqMtQHEhuM-kCsG3TpuqNEWpW-NSwWkOWf1phyphenhyphengIuaoeSGpiJqAgeyfp3wVsJQULcVJAlRX22zzDkFq0k_FmMan3LXejUmGGm_lg/s1600/Cannon-plugs.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrtDuTKsAtCO09fYX5FbnEc2dF2locysScTLHqMtQHEhuM-kCsG3TpuqNEWpW-NSwWkOWf1phyphenhyphengIuaoeSGpiJqAgeyfp3wVsJQULcVJAlRX22zzDkFq0k_FmMan3LXejUmGGm_lg/s320/Cannon-plugs.JPG" /></a></div>
<p>
The dirt and crud even lend a period correct feel to these, so as not to bum out the vintage zombies. I jest, partially.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLKLM6Slj9J_cLBviYBtCV0PZvFWaPGHnRmfkfWqdWxY3sJRdNob9aWJ9APUYsrDzqvdEOnocmTklZUxA4xqDFGmJfP1QKuC4vCkIdHS3PA1qY_LlE8RuDqAXIMZCIEbK92OvE_w/s1600/insulate-HIz.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLKLM6Slj9J_cLBviYBtCV0PZvFWaPGHnRmfkfWqdWxY3sJRdNob9aWJ9APUYsrDzqvdEOnocmTklZUxA4xqDFGmJfP1QKuC4vCkIdHS3PA1qY_LlE8RuDqAXIMZCIEbK92OvE_w/s320/insulate-HIz.JPG" /></a></div>
<p>
So a bit of heat shrink on the blue hi-Z feed, connect chassis to 1, and I decided to jam orange as "hot" on pin 2 because it's a "warmer" color than yellow. Completely scientific like. Whatever. The mic works, I like the sound, it will get used.
<p>
Apologies, I don't seem to have taken a picture of the completed unit. It looks like the connector end of a standard microphone, my guess is that if that isn't explanation enough, this mod might not be for you.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com2tag:blogger.com,1999:blog-33019505.post-16331227476741285652014-04-11T03:00:00.000-07:002014-04-11T03:00:11.131-07:00Drilled out the rivets securing the back panel of the IRP Voicematic to allow a bit of useful modification.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcCjFJZCbZ-6lCFi608kAuDDaoUrPIwQX61-vZBhGK22IB3TrgwpqNaKwTghvwDbMwFpaHtqwMInfS0IRTVqOmgjv4wGxJj13qJ2NXeL__7gIMq2ZyyfwwYGdDDcVPbH0IWyX39w/s1600/IRP-backplane.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcCjFJZCbZ-6lCFi608kAuDDaoUrPIwQX61-vZBhGK22IB3TrgwpqNaKwTghvwDbMwFpaHtqwMInfS0IRTVqOmgjv4wGxJj13qJ2NXeL__7gIMq2ZyyfwwYGdDDcVPbH0IWyX39w/s320/IRP-backplane.JPG" /></a></div>
<p>
It's a little difficult to discern here, but there's an uninsulated wire in between the black and white twisted pair along the backplane buss. According to my scope, the bare wire is the audio feed line from the independent cards to the master summing section. Visible are my sloppily hand aligned holes.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmOhLN4MTwmXYrStItzlldh33OIVylxb2-2zam4AKsTDvWlnMthYdD99EQTOqh52N0MkPW-Af98VVJQ4KRKnl0vKBXWrT1YQr-5GY0llO3Z_g5Y2qyNMIZxR_SsbzL1SrD50P7Xg/s1600/IRP-outputs-wired.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmOhLN4MTwmXYrStItzlldh33OIVylxb2-2zam4AKsTDvWlnMthYdD99EQTOqh52N0MkPW-Af98VVJQ4KRKnl0vKBXWrT1YQr-5GY0llO3Z_g5Y2qyNMIZxR_SsbzL1SrD50P7Xg/s320/IRP-outputs-wired.JPG" /></a></div>
<p>
The idea here is that since all the cards output direct to this buss wire, I can get away with installing interrupting jacks (Switchcraft 12A) so that the card feeds the tip directly, which is shunted to the combined buss when nothing is plugged into the jack. I've opted to only go so far as metal work on the 11/12 hole, as I don't have a card for that pair. So yeah, I'm leaving a HOLE in the case. Never know when it might come in handy.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHB2ZNSbDatZCS0cm2DYf02YAhTR8bTeFHv6g-GlS2ubzUJD38_FZivGqJgVwMEwsDAdJ3rdQy2RIUbNUQZvPb59Q1Gkjz4Tgg0YfEC1YEXMg0FqUgtvcWjAYCsFFjz0_OrZy7pA/s1600/IRP-phone-jacks.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHB2ZNSbDatZCS0cm2DYf02YAhTR8bTeFHv6g-GlS2ubzUJD38_FZivGqJgVwMEwsDAdJ3rdQy2RIUbNUQZvPb59Q1Gkjz4Tgg0YfEC1YEXMg0FqUgtvcWjAYCsFFjz0_OrZy7pA/s320/IRP-phone-jacks.JPG" /></a></div>
<p>
Functional, though the recovery amplifier provides for considerable gain, so direct patching the two input card has a much lower level than what is available at transformer output. I guess that's what booster pedals are for.. HAHA.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com0tag:blogger.com,1999:blog-33019505.post-58033471867410423082014-04-09T06:49:00.000-07:002014-04-09T06:52:07.939-07:00Here are some more shots of the woodwork on the TIC 500 set (both of which are now recapped, and to varying degrees functional).
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYCDupt2Nob8-Oqpw9PCJ7JS7k1xQNTOipzKzMBHPbT-ysNu56y2dhR1MnkvmdDPVqlGcD8L-REKTLI778IqFOrUOcCCMROoDBbxT0YyWGyj6FJv-d2paoWa0oa2UihUkmastIPg/s1600/rack-rail.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYCDupt2Nob8-Oqpw9PCJ7JS7k1xQNTOipzKzMBHPbT-ysNu56y2dhR1MnkvmdDPVqlGcD8L-REKTLI778IqFOrUOcCCMROoDBbxT0YyWGyj6FJv-d2paoWa0oa2UihUkmastIPg/s320/rack-rail.JPG" /></a></div>
<p>
Assembly details, fairly apparent.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1X3E7ylZ7XE7kyNziltwz0RLEQxSLjKBOhXimVX4xPZ0JqjoxVw-JvZtLHXaY-Be4utPVCfrTHo_4R0s07ib-EH6L_cbBGWXC5zgCMb4IM7xbzv1MGXCINpjhKQgjbqx9Fuvnrg/s1600/corner.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1X3E7ylZ7XE7kyNziltwz0RLEQxSLjKBOhXimVX4xPZ0JqjoxVw-JvZtLHXaY-Be4utPVCfrTHo_4R0s07ib-EH6L_cbBGWXC5zgCMb4IM7xbzv1MGXCINpjhKQgjbqx9Fuvnrg/s320/corner.JPG" /></a></div>
<p>
Precision.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigFyGR4b5_sdgNa3xMRK-XkogC-Isq6XBP5_gk5RjGYk3kxmte5hvJbeeoAjBewpP1sfdbjkxQN7JIqShBgVQ4qenU1ite9us35vN9rXnALcCXnFxeZ-X__oEh9N65GhM62OJssQ/s1600/power-hole.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigFyGR4b5_sdgNa3xMRK-XkogC-Isq6XBP5_gk5RjGYk3kxmte5hvJbeeoAjBewpP1sfdbjkxQN7JIqShBgVQ4qenU1ite9us35vN9rXnALcCXnFxeZ-X__oEh9N65GhM62OJssQ/s320/power-hole.JPG" /></a></div>
<p>
Each unit is self powered, the large bodied grounded plug assembly just fits through this hole necessitating a keyway for other cord.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFC3M-0sPs_QOV4glTUU2F0Mi6OVPetdK5YDtPjPcT9ozC1kdmlcQ1yn7hIG7KkMDpXK_img9-S3Uu_7rKU9j7ZVDhKfneWldukiOmeK7U2lOMFy5ekBT6dUoLRcyguZEiGAjh5Q/s1600/handle.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFC3M-0sPs_QOV4glTUU2F0Mi6OVPetdK5YDtPjPcT9ozC1kdmlcQ1yn7hIG7KkMDpXK_img9-S3Uu_7rKU9j7ZVDhKfneWldukiOmeK7U2lOMFy5ekBT6dUoLRcyguZEiGAjh5Q/s320/handle.JPG" /></a></div>
<p>
Another peek at woodwork, only one side is drilled like this..
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKwVzEJ-ODfBincVeaCYtaAfbU1ZeKEY6YmWito-tPyoQ67m_1u9cFmOs8CwLdctmEUc01bMZzQGlAD0nI_6JO6gx3hmxhbdzQgXSlxgwqrCTugobBoHGpCGB-hERaSo2ctSaR1w/s1600/keyhole.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKwVzEJ-ODfBincVeaCYtaAfbU1ZeKEY6YmWito-tPyoQ67m_1u9cFmOs8CwLdctmEUc01bMZzQGlAD0nI_6JO6gx3hmxhbdzQgXSlxgwqrCTugobBoHGpCGB-hERaSo2ctSaR1w/s320/keyhole.JPG" /></a></div>
<p>
..which makes for a nice view.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtKcFqpj0jzUHIhPSqhAK_05bTRB_zh6IbKkuIOb8s30Xw-RyxfWJha6OaHjo6iU4NiXvYTRUDjHI7VYG1U30Rril5l0_xWFIlsGJQ6lDWBnkOiUfs0ewd09ubHkjENP1bTu9yAA/s1600/top-grill.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtKcFqpj0jzUHIhPSqhAK_05bTRB_zh6IbKkuIOb8s30Xw-RyxfWJha6OaHjo6iU4NiXvYTRUDjHI7VYG1U30Rril5l0_xWFIlsGJQ6lDWBnkOiUfs0ewd09ubHkjENP1bTu9yAA/s320/top-grill.JPG" /></a></div>
<p>
Though to be fair, the ample ventilation provides for largely unrestricted observation.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirOAspEmDf7jZL1xoVqu-CWdP94zpzwd_wlX7McZYJj0ns0mbGRuFTjR12Lio-c8RLb8bLiWyj2dIbipyM5Z8clkSjRwVgK0mvmR_mH02GM6WRVnXwclSAcEuTJf0hbyMtA9tmMw/s1600/500schematic.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirOAspEmDf7jZL1xoVqu-CWdP94zpzwd_wlX7McZYJj0ns0mbGRuFTjR12Lio-c8RLb8bLiWyj2dIbipyM5Z8clkSjRwVgK0mvmR_mH02GM6WRVnXwclSAcEuTJf0hbyMtA9tmMw/s320/500schematic.JPG" /></a></div>
<p>
I found service data! TIC was evidently acquired by Acton Labs in the mid 1950s (or thereabouts), and in reading this thread it would seem TIC was H.H. Scott's company after departing GenRad? <a href="http://antiqueradios.com/forums/viewtopic.php?f=8&t=221316">http://antiqueradios.com/forums/viewtopic.php?f=8&t=221316</a><br>
Regardless, I'm happy to have a roadmap I can follow should I decide to tackle the motorboating issues. I'm somewhat on the fence about that, because of an interactive response to signal that nudges these into musical instrument territory.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com0tag:blogger.com,1999:blog-33019505.post-56846004622232915022014-02-10T07:26:00.000-08:002014-02-10T07:26:14.764-08:00Picked up a Technology Instruments Corp Dual Type 500 AR wideband voltage amplifier last year, because, well.. look at it.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiogAx9X4Q0v82O2jAMjWqZ8r6B6Gs7jQuotWaTA6BSDcsuWOBGmhURwF3IixCZ3jDu2SwF1Sa-ztZuGAPR0pYyd_P2NVMnKIlYjQKIlzX_o-1zQJq5DZwwDCzcRlSc0le29dPv8g/s1600/TIC500.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiogAx9X4Q0v82O2jAMjWqZ8r6B6Gs7jQuotWaTA6BSDcsuWOBGmhURwF3IixCZ3jDu2SwF1Sa-ztZuGAPR0pYyd_P2NVMnKIlYjQKIlzX_o-1zQJq5DZwwDCzcRlSc0le29dPv8g/s320/TIC500.JPG" /></a></div>
<p>
Tired phrase, but: they don't make them like they used to.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUfdf5Nw_32PzJx2aAgWSRaW2u-W-lrb9JomNPAjUsQOepGR4Qsy_hSu3GPOCLYKz-iu5ifjiRWv8LWTEIh-I7yqStqeWKNSj7kEHCV6az8SbSvdb7FMSbZO9o_OfBVrqmvyt-hQ/s1600/TICface.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUfdf5Nw_32PzJx2aAgWSRaW2u-W-lrb9JomNPAjUsQOepGR4Qsy_hSu3GPOCLYKz-iu5ifjiRWv8LWTEIh-I7yqStqeWKNSj7kEHCV6az8SbSvdb7FMSbZO9o_OfBVrqmvyt-hQ/s320/TICface.JPG" /></a></div>
<p>
Fairly no nonsense control set.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjegRHbB7IwcgUCXxCHYE90OgT1CP0xluLDdDCEIgks2pXnQBFxiMpku6zaUbS29vaH_Gmd9QaZ1mJHMqb9ngdLTFP3Oa5VdwdPlL95Wwot5ceCdp9BlC41o_sSpSGCbKHOfASptg/s1600/ITCpilot.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjegRHbB7IwcgUCXxCHYE90OgT1CP0xluLDdDCEIgks2pXnQBFxiMpku6zaUbS29vaH_Gmd9QaZ1mJHMqb9ngdLTFP3Oa5VdwdPlL95Wwot5ceCdp9BlC41o_sSpSGCbKHOfASptg/s320/ITCpilot.JPG" /></a></div>
<p>
Yes, it glows in that logo.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgN_8a9_LCNP3RVkEsZG9BdogapmMNqNO3AQvjzVT3XS2GxcoODYp5SiZhXsb2qlaNL7uyusFfW6uD3BwenZnOvd9ZqI6LT2pMkk4A7G-gSD_0kudScRNcbitSC6DZz81Zx9fLpAg/s1600/TICbattery.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgN_8a9_LCNP3RVkEsZG9BdogapmMNqNO3AQvjzVT3XS2GxcoODYp5SiZhXsb2qlaNL7uyusFfW6uD3BwenZnOvd9ZqI6LT2pMkk4A7G-gSD_0kudScRNcbitSC6DZz81Zx9fLpAg/s320/TICbattery.JPG" /></a></div>
<p>
Cracking the units open revealed a somewhat ugly bias battery assembly, comprised of two 625 mercury batteries bound together. This is only switched in at 1000 gain, and so I opted to remove it with the intent to replace in event of malfunction. My applications are confined to the audible spectrum of sound (as opposed to full 5Hz-2MHz claimed) so a little non-linearity may actually be welcome.
<p>
There's really only one way to find out.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9cLfgGho1-wN3uJ67LKwFmXzYhzMj7zShxwE_OU7Ahp16R2pcJY8YE1pJDWVEPl-cGcfcUBsr1jr7a0tbCwackt2a_G_MEjZccv0T4s7_-9eFxACOy9q2fElkYUeBwgq1zLwthg/s1600/TICoeTOP.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9cLfgGho1-wN3uJ67LKwFmXzYhzMj7zShxwE_OU7Ahp16R2pcJY8YE1pJDWVEPl-cGcfcUBsr1jr7a0tbCwackt2a_G_MEjZccv0T4s7_-9eFxACOy9q2fElkYUeBwgq1zLwthg/s320/TICoeTOP.JPG" /></a></div>
<p>
Original circuit, gutshot topside.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEDZ8OW7TVLTqe94Gtkw0_X5NpkT2WM_SYCXf2q9HUYW_2FaERMtO299heAmWKDHbE8y-9fWC8ZrOvx5MhEptkzwEfksyA7mORD5UorZE_fhLBIvQgtsqkbY2KlTtY14tfgSOj9Q/s1600/TICoeBOTTOM.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEDZ8OW7TVLTqe94Gtkw0_X5NpkT2WM_SYCXf2q9HUYW_2FaERMtO299heAmWKDHbE8y-9fWC8ZrOvx5MhEptkzwEfksyA7mORD5UorZE_fhLBIvQgtsqkbY2KlTtY14tfgSOj9Q/s320/TICoeBOTTOM.JPG" /></a></div>
<p>
Original circuit, gutshot from below. My intent is to replace the electrolytics and the selenium, and then give it a listen.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhP70zC1ioleVaSYu7us_II0VahGD9h0uAySrGSI6EEqPeS0fpjO6v-3oZS5BGTUB2V7fTx3QsnKllxf1K8kqc0OgoPyf6DVu3bwYVqhiqiQEdiKVrGOMA64UzjjAptpF8gGGEWxA/s1600/TICreTOP.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhP70zC1ioleVaSYu7us_II0VahGD9h0uAySrGSI6EEqPeS0fpjO6v-3oZS5BGTUB2V7fTx3QsnKllxf1K8kqc0OgoPyf6DVu3bwYVqhiqiQEdiKVrGOMA64UzjjAptpF8gGGEWxA/s320/TICreTOP.JPG" /></a></div>
<p>
Modern parts make for a roomier experience.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrHH9_ATJOzqF3UvSz3o4xUmUG_22fRrdO8rnYm736X0qwIo1G0innq3GktnwkwW245-t_V5YhA385MU2mFyhCfddL5neDVL_iYxJTQcJ7jsLcyOv519AdJaNMPOVJFDrrGR0TsQ/s1600/TICreBOTTOM.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrHH9_ATJOzqF3UvSz3o4xUmUG_22fRrdO8rnYm736X0qwIo1G0innq3GktnwkwW245-t_V5YhA385MU2mFyhCfddL5neDVL_iYxJTQcJ7jsLcyOv519AdJaNMPOVJFDrrGR0TsQ/s320/TICreBOTTOM.JPG" /></a></div>
<p>
A 100pf mica domino cap (visible on the original unit) has been installed on the wafer switch.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQ4XOfmZhUodpI4YmibvTPp4bPPBrd6PfSxVwfK4pa1usQlCds5HyoObgP9S1cXI1BFLGaO44gLK1SMjuBW1iAf29onbMo40vUqiArLZ4301990cY8g6fble9zlYHGAOflVMkM4Q/s1600/recap.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQ4XOfmZhUodpI4YmibvTPp4bPPBrd6PfSxVwfK4pa1usQlCds5HyoObgP9S1cXI1BFLGaO44gLK1SMjuBW1iAf29onbMo40vUqiArLZ4301990cY8g6fble9zlYHGAOflVMkM4Q/s320/recap.JPG" /></a></div>
<p>
I've been going the budget route on electrolytic capacitors, building ugly little clusters costs less than a quarter of repop multisection can caps. These are not museum collection pieces, these are supposed to be used.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvppxdS78bVR5Nds5NPKaCcHA9Qa2HUPTrw8kqlN6TSbNLMETCmyBLJoIkPzXwAEBjVHhzRlF0NIOo9Jj_WCfrIaWJ_uh_nmRlEwwsgzfUS-xGj-Tr6YI_TqHycKufMU4eJToTbw/s1600/TICsi-replace-power-cable.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvppxdS78bVR5Nds5NPKaCcHA9Qa2HUPTrw8kqlN6TSbNLMETCmyBLJoIkPzXwAEBjVHhzRlF0NIOo9Jj_WCfrIaWJ_uh_nmRlEwwsgzfUS-xGj-Tr6YI_TqHycKufMU4eJToTbw/s320/TICsi-replace-power-cable.JPG" /></a></div>
<p>
This was an easy fix that entailed shortening the power cable about a foot from the inside.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUnldO_8d3NvCDdRnYUlcPaRSkiDjWi_HScQ5AU3IzMf42zi80HzjbO4KJrv-E-u7LPrIKUdN5TLPxJ9d3Fxm1CfNWFFdB_mEVDMLpI1Vo_67IV8Ti67CInk2BivUNDbfIsR46WA/s1600/build-quality.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUnldO_8d3NvCDdRnYUlcPaRSkiDjWi_HScQ5AU3IzMf42zi80HzjbO4KJrv-E-u7LPrIKUdN5TLPxJ9d3Fxm1CfNWFFdB_mEVDMLpI1Vo_67IV8Ti67CInk2BivUNDbfIsR46WA/s320/build-quality.JPG" /></a></div>
<p>
General purpose gutshot.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgfs_3DoIToQO-cDhrdt3QCHrV2y1aHyXfqeuzEl2U0wHnvR6e8G-p3b7zQNG3CSEheM_YHxyB-l5mB1TPB5Y7ZD0Ku-1mztiRl_wEr6Gib8PE2O6bXWuuA1RghQmFHj3bZKVMsw/s1600/screwhead.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgfs_3DoIToQO-cDhrdt3QCHrV2y1aHyXfqeuzEl2U0wHnvR6e8G-p3b7zQNG3CSEheM_YHxyB-l5mB1TPB5Y7ZD0Ku-1mztiRl_wEr6Gib8PE2O6bXWuuA1RghQmFHj3bZKVMsw/s320/screwhead.JPG" /></a></div>
<p>
The earlier, original screw is quite evident compared to the newer screw, both of which exhibit a level of quality I don't see in a lot of current hardware.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhNcjftd4guF4xjpwCasv80fKEnh4QysNjNIO24cUKs6NRR2QCbaekUeqr3AkcIA6XEYDO_tqNmBo6y7Vtrsjt5UJ4094ipfBABVIyqskrrqwsqidK0zYDlcOdBzx3rKOPH-uEPkw/s1600/terminated-input.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhNcjftd4guF4xjpwCasv80fKEnh4QysNjNIO24cUKs6NRR2QCbaekUeqr3AkcIA6XEYDO_tqNmBo6y7Vtrsjt5UJ4094ipfBABVIyqskrrqwsqidK0zYDlcOdBzx3rKOPH-uEPkw/s320/terminated-input.JPG" /></a></div>
<p>
So, after working one unit over I was slowly bringing it up on a variac and started to read voltage swings on output, one pulse every two seconds or so. Slow enough to confuse my multimeter on both AC & DC settings. The scope displayed a pulse that jumped toward the top of the scale, which indicated a frightful signal to be feeding gear downstream.
<p>
Plugging this 75 ohm terminator from my video junk into the input happens to snub the oscillation. It took me a little while to connect this particular set of dots.. after discovery of the motorboating, I shelved this for a while to clear my head. Then I observed that it didn't oscillate at 10, various resistors strapped on the output, loading the input with a signal source and listening to output, generally just fooling around with it brought about this observation.
<p>
So, the plan is to terminate the input with the largest resistor I can to prohibit runaway, which, I might add, only affects this unit (before and after recap). I dug into this one first because it was operationally impaired, so I could have a functioning unit to A/B while troubleshooting, should the need arise.
<p>
All in all, I would not describe this as a high fidelity preamp, it does however go deeply enough into the realm of character to justify having around. Plus, it's pleasing to the eye. crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com0tag:blogger.com,1999:blog-33019505.post-25466365543872585892013-12-13T20:19:00.000-08:002013-12-13T20:19:23.985-08:00Above my racks in the studio I have some old light bar lamps that have the sockets wired up in series. This is to achieve two aims: a nice mild illumination that allows me to see while not being bright and extended useful service life of the incandescent bulbs.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKsXtwUhbtMPB-RJPkFJnv0Ak7YD6kzUaZurmk75XZpEDUn05yvL2w7jHze3sRqCfdaONkbo9VO9Y-mHJSzEoIHrc2spCBi25Ji_lIQ6UQSbWViG6fcAp0kvH7RWiLY2w7b3Fbvg/s1600/filament.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKsXtwUhbtMPB-RJPkFJnv0Ak7YD6kzUaZurmk75XZpEDUn05yvL2w7jHze3sRqCfdaONkbo9VO9Y-mHJSzEoIHrc2spCBi25Ji_lIQ6UQSbWViG6fcAp0kvH7RWiLY2w7b3Fbvg/s320/filament.JPG" /></a></div>
<p>
At least, extended (my intent was indefinite) life span was part of the idea. Turns out having a bunch of bulbs overhanging the rack provides temptation to hang cables. Mind you, light bulbs are not load bearing. This one remained illuminated for about 10 seconds after the glass fell away. I was about to grab the camera when it flared out into what you see here.
<p>
No more using conveniently placed lightbulbs as cable hangers for me! Happy Friday.
<p>
In other news, I'll be gigging the reverb unit tomorrow, so I expect I should have some "I'm finished!" content soon.
crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com0tag:blogger.com,1999:blog-33019505.post-55721737438657636862013-12-09T08:04:00.002-08:002013-12-09T08:37:42.334-08:00Our temperate region was hit with an abnormally cold storm, derailing my plan to drive across town and use appropriate power tools to fabricate an enclosure for the reverb amplifier. I was actually toying with the idea to clamp a temporary table to my radial arm saw project (future instalment) when I came across an old Bach trumpet case I had salvaged from a pile of enclosures that were slated for a stop in a dumpster.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiu5T_sOcIPkGv8UpTNcVB_MW_UOWVQBhyphenhyphenj8D61VFVmvLpGNPkHGfrd-aptryBqJXIZOn2LX_7CHOyTEc2oRZCNHotBejjCnXYuVDYPuOfvkBp4jcl-mWpOuHmaOLH1OKxDpL0lFg/s1600/gutted-bach.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiu5T_sOcIPkGv8UpTNcVB_MW_UOWVQBhyphenhyphenj8D61VFVmvLpGNPkHGfrd-aptryBqJXIZOn2LX_7CHOyTEc2oRZCNHotBejjCnXYuVDYPuOfvkBp4jcl-mWpOuHmaOLH1OKxDpL0lFg/s320/gutted-bach.JPG" /></a></div>
<p>
According to the reverb pan, this case will work out just fine.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaJCSAlqI7HOuKVrg9_HPPGclgSdc3QfVflgFSpnwb0Nq05bS1uqZdfZEK-46KvpxAWRbAD7lcY9nVJ5TM9TeAd-4Ch9Ml6hgoXeRFDs44KAWuEdgw5hd3FOwzyW27AxRW_1sG5w/s1600/monkeyfur-remnants.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaJCSAlqI7HOuKVrg9_HPPGclgSdc3QfVflgFSpnwb0Nq05bS1uqZdfZEK-46KvpxAWRbAD7lcY9nVJ5TM9TeAd-4Ch9Ml6hgoXeRFDs44KAWuEdgw5hd3FOwzyW27AxRW_1sG5w/s320/monkeyfur-remnants.JPG" /></a></div>
<p>
Gutting it was not nuisance free.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKDwDjQFwoUdRsgcdYBDSyhuOp25XXzNh_HuPzowmj_hvzalYg5vN-kDOyvSRW0K9qJdWYGf-apQx_8rh3kd0Wb3ySdwRjrJPjjR6pg1TERYBe4o3KBtJFEuLzx_VVtybRIqTXkA/s1600/monkeyfur.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKDwDjQFwoUdRsgcdYBDSyhuOp25XXzNh_HuPzowmj_hvzalYg5vN-kDOyvSRW0K9qJdWYGf-apQx_8rh3kd0Wb3ySdwRjrJPjjR6pg1TERYBe4o3KBtJFEuLzx_VVtybRIqTXkA/s320/monkeyfur.JPG" /></a></div>
<p>
The glued in monkey fur (remaining after I peeled the fabric backing away, which was a chore in itself) gave me ample opportunity to oil up my language.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsW4GTXWZtaCt6R-qwW9wBeUHtyy9cYP2u49mAzx9cCeUs4Gm_oznCxYIGWQ7yuO69enp_RFeTeCvy1-m5lp-mW7MLI8KXSt7Ao3F5WDrgqHQW8wOA92becsJwIr8H2AqdzVNaNg/s1600/case-fit.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsW4GTXWZtaCt6R-qwW9wBeUHtyy9cYP2u49mAzx9cCeUs4Gm_oznCxYIGWQ7yuO69enp_RFeTeCvy1-m5lp-mW7MLI8KXSt7Ao3F5WDrgqHQW8wOA92becsJwIr8H2AqdzVNaNg/s320/case-fit.JPG" /></a></div>
<p>
Ultimately, once the fire hazard levels of fluff were removed the case continued to show promise. The area to the right where the shim block is will be filled with the B+ transformer I'm adding to the party.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT7G1v4mUyETMLCD55r2X48OQ6gkRLFgVZlP_G4BU_2h6wEFuni3BNvwlINJLhHGuczPhaA9vwyDKii34sfQHDMHG_B-OPEzLpcaLcCu1NicbTf9r-9SM2A7feUE8KYaV0fAbtPg/s1600/crowbar0.15cap.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT7G1v4mUyETMLCD55r2X48OQ6gkRLFgVZlP_G4BU_2h6wEFuni3BNvwlINJLhHGuczPhaA9vwyDKii34sfQHDMHG_B-OPEzLpcaLcCu1NicbTf9r-9SM2A7feUE8KYaV0fAbtPg/s320/crowbar0.15cap.JPG" /></a></div>
<p>
Before I get that far, however, I want to address the incorrect capacitor I noticed the <a href="http://crochambeau.blogspot.com/2013/12/200th-post-let-me-take-moment-to.html">last time I posted</a>, because the additional transformer is too large to mount to the chassis and performing work with a tethered chunk of iron is going to push the nuisance aspect a bit. Here I've pulled the 0.01 Black Cat and have eased a 0.1 Aerovox Duranite into the slot.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgc060CTRvEE3RQ5JN8UqSoNWFy50GeCKfnRgNkpagR7qutqEVD5wKz-WjeX_B_fAs2qxgcM0loZoK7GnI67Zv4Nuj0OidN1XFaWVdkxW0KM3lIiJpSOGnBTHxyFf96bzOErg2XVA/s1600/in-position.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgc060CTRvEE3RQ5JN8UqSoNWFy50GeCKfnRgNkpagR7qutqEVD5wKz-WjeX_B_fAs2qxgcM0loZoK7GnI67Zv4Nuj0OidN1XFaWVdkxW0KM3lIiJpSOGnBTHxyFf96bzOErg2XVA/s320/in-position.JPG" /></a></div>
<p>
Access to the leg of the potentiometer necessitated the temporary displacement of the Domino cap, here everything is in position and ready for soldering.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3fwtpecpgq3UZeHvaX1JUDGxgPJSV1qJ1IxLYxXxSHyjnMBtpoIGca_eKoRjGcHLWrzeOVlIlfAhUmB5QUgGCXPSLki56gfiQNoU55f7ajNEgTpUbpAANAf7UFJQfhdsoJGLOvA/s1600/plate-side.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3fwtpecpgq3UZeHvaX1JUDGxgPJSV1qJ1IxLYxXxSHyjnMBtpoIGca_eKoRjGcHLWrzeOVlIlfAhUmB5QUgGCXPSLki56gfiQNoU55f7ajNEgTpUbpAANAf7UFJQfhdsoJGLOvA/s320/plate-side.JPG" /></a></div>
<p>
Once the potentiometer assembly was buttoned back up it was time to address connection to plate leg of the tube socket, however, the longer package in the 0.1 cap put the B+ a little too close to the grounded screw for my comfort.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPD67IKHFraAjcw6P-_5PPtYRybebwG0grleNB-lQGJERRqY8hpahhzbBY-EHcCSk5_2Df-SqJEZvkP58ZgSJJrFrMzwkHwLqpUig5dHE9u6cLNBR87hzokcX_wOAHacMHMD5ABg/s1600/installed.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPD67IKHFraAjcw6P-_5PPtYRybebwG0grleNB-lQGJERRqY8hpahhzbBY-EHcCSk5_2Df-SqJEZvkP58ZgSJJrFrMzwkHwLqpUig5dHE9u6cLNBR87hzokcX_wOAHacMHMD5ABg/s320/installed.JPG" /></a></div>
<p>
Tasteful application of brute force corrected the interference fit.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIw7xipSX3CyJOOzQ0gKILGFQXI7EJhCUCMgRVy1ZO-BuZ1PHyKwAamvFVsFmCCcG4QJEJ28_fa374GMjM9dVmlJpZNNvge6Zo38ivr53vr9JNY-p5KWihBq9VvVOLiY1b2bM_Cw/s1600/bent.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIw7xipSX3CyJOOzQ0gKILGFQXI7EJhCUCMgRVy1ZO-BuZ1PHyKwAamvFVsFmCCcG4QJEJ28_fa374GMjM9dVmlJpZNNvge6Zo38ivr53vr9JNY-p5KWihBq9VvVOLiY1b2bM_Cw/s320/bent.JPG" /></a></div>
<p>
Nice round bend taking up the slack.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3mFl0DtwwglyLn_sjg4_vNNl3qIgXVsgkfZnUCtQTlsKOK58zt89n7y48ln_S-MrJpTmJepZsCEQhOmg16t4F5eaNNMygSb9JHj2zbS78Y3DIOgxqkE3olDwYMJvadYcFvQEzTQ/s1600/transformer-piggyback.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3mFl0DtwwglyLn_sjg4_vNNl3qIgXVsgkfZnUCtQTlsKOK58zt89n7y48ln_S-MrJpTmJepZsCEQhOmg16t4F5eaNNMygSb9JHj2zbS78Y3DIOgxqkE3olDwYMJvadYcFvQEzTQ/s320/transformer-piggyback.JPG" /></a></div>
<p>
With the chassis sorted it was time to address the previously discovered deficiency in the higher voltage secondary of my installed transformer. I had toyed with the idea of putting a step up transformer across the 50 volt CT winding, but tests indicated that it was overburdening the 50 volt winding, so that plan was scuttled and this transformer was brought in, which provides roughly 200 volts DC once rectified, which is plenty for me.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiupTC7kc6JptDI49TSZ2hRN9Es6JWpvTdeSCkCgrL2Yd_W5nfTISnNGIH9l5NnXkEE0ZPAuIYeSFNQjpVUccu02P5RVqt_uSXhsvvPtQzeCOd3HZ1vCyV8sdvKLaZokey1aLxAdA/s1600/rectifier-revision.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiupTC7kc6JptDI49TSZ2hRN9Es6JWpvTdeSCkCgrL2Yd_W5nfTISnNGIH9l5NnXkEE0ZPAuIYeSFNQjpVUccu02P5RVqt_uSXhsvvPtQzeCOd3HZ1vCyV8sdvKLaZokey1aLxAdA/s320/rectifier-revision.JPG" /></a></div>
<p>
I got to fill in the empty eyelet with a ground reference due to no center tap on the transformer.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg844AVPUzGhpD8L8Y-oi-7bMRe_zf6NAko2FxQ3TZsLdvi_NJ5qLKOUks6dLjDkzPUYrYurRnTV00q2hjs4yGKWkOrqWaEqcR4V3K8c6i8KKB74zLdnqIjfhAPzul-XEdDAOn5Kw/s1600/snowed.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg844AVPUzGhpD8L8Y-oi-7bMRe_zf6NAko2FxQ3TZsLdvi_NJ5qLKOUks6dLjDkzPUYrYurRnTV00q2hjs4yGKWkOrqWaEqcR4V3K8c6i8KKB74zLdnqIjfhAPzul-XEdDAOn5Kw/s320/snowed.JPG" /></a></div>
<p>
With my car still snowed in (we reached -10F/-23C and the old moisture bearing door seals quite literally have frozen this car into a solid shell, though I am certain the aircooled motor would fire right up - if only I could get inside to operate the car) I decide to hand carve the enclosure.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizlTzAEINK9C2wVTMKrsQamjIgF6JDNRqWu2flmSd80dO-14bjxN8QdmlYc-TglyESb5LoQhR7MDbqJZ4ScvYXtbyF79WfLxtxZGDxsmqrJhyphenhyphenXjd8XCgAtCFZAIji6ImYmztzDow/s1600/monkeyfur-shavings.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizlTzAEINK9C2wVTMKrsQamjIgF6JDNRqWu2flmSd80dO-14bjxN8QdmlYc-TglyESb5LoQhR7MDbqJZ4ScvYXtbyF79WfLxtxZGDxsmqrJhyphenhyphenXjd8XCgAtCFZAIji6ImYmztzDow/s320/monkeyfur-shavings.JPG" /></a></div>
<p>
Naturally, the larger knife I would normally reach for in this instance is currently TRAPPED INSIDE MY CAR, so I had a go with an old box knife...
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBPTvUbuK7Pnr3ImxfEBiatmyAgMVBSezW_qjDNviAgozA8iYopFKJ0SaJ-cMupc_21lFOQ7rSBVOBKObRUHiQjauTftwPd0W8bpu0GtYN5aXtLf3MmIL4KyfHJ7DPhMnLdjDUEQ/s1600/chair-shavings.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBPTvUbuK7Pnr3ImxfEBiatmyAgMVBSezW_qjDNviAgozA8iYopFKJ0SaJ-cMupc_21lFOQ7rSBVOBKObRUHiQjauTftwPd0W8bpu0GtYN5aXtLf3MmIL4KyfHJ7DPhMnLdjDUEQ/s320/chair-shavings.JPG" /></a></div>
<p>
...which resulted in many shavings.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifB1574gugeDwfoIWqTR0TOB0pxItO9i62MHe7m_WwmBJtzCCONuC44WinJvJG3gNhBra8eNVtUdlhRoaxEu0HHDa6opsO1XEACzpEAVOh47PFMQBm8QKA3Hj-kBivtBO4zcpGGA/s1600/control-panel.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifB1574gugeDwfoIWqTR0TOB0pxItO9i62MHe7m_WwmBJtzCCONuC44WinJvJG3gNhBra8eNVtUdlhRoaxEu0HHDa6opsO1XEACzpEAVOh47PFMQBm8QKA3Hj-kBivtBO4zcpGGA/s320/control-panel.JPG" /></a></div>
<p>
I think in the end it will all be worth it though.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com3tag:blogger.com,1999:blog-33019505.post-69091678896182092562013-12-07T08:45:00.002-08:002013-12-07T08:45:42.566-08:00200th post! Let me take a moment to explain my extended leave. The notion that I was starting a bunch of threads then leaving them out to wither and fade away was weighing down on me a bit. See, as I would climb the archives for a kernel of data (these posts are probably more for my own benefit than anyone else's, though I do appreciate the support and positive feedback when it comes up) it became more and more apparent that the greater majority of my posts were either showcasing an object (not my intent) or lacked closure.
<p>
In short, it really seems a scatterbrained collection of halfway theres, and I made the command decision to NOT "pollute" these logs with more half finished business until something started was ushered to completion. That something is the <a href="http://crochambeau.blogspot.com/2013/06/after-breaking-old-japanese-chassis.html">outboard reverb build</a> I have been dancing around for more years than I care to contemplate. So this blogging process was shelved while I did other things, make no mistake, I haven't wandered away from flowing solder - I just couldn't bring myself to post about anything other than the reverb, until it's done.
<p>
Yes, it really has taken me months to move on beyond chassis layout and punching holes (arguably more involved) to actual circuit wiring (you know, the FUN stuff). Ask me about painting my car next.
<p>
No, don't.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhW6_60zrDjSVDSFMXWkJSci9wNKkThbqUjn1CpJzN3yBmIJ1Ztuiwa4E4jvqj0en2WUKfJ65PAosGdFMGUOUM8HAAILVnZJ30zFCVo9iUJIyftxlKfGeaUFFHhQrs8oGX43Y_KMQ/s1600/gutside.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhW6_60zrDjSVDSFMXWkJSci9wNKkThbqUjn1CpJzN3yBmIJ1Ztuiwa4E4jvqj0en2WUKfJ65PAosGdFMGUOUM8HAAILVnZJ30zFCVo9iUJIyftxlKfGeaUFFHhQrs8oGX43Y_KMQ/s320/gutside.JPG" /></a></div>
<p>
At any rate, progress has been made so here I am. For those that don't already know, the Fender 6G15 reverberation amplifier is loosely based on the Fender Champ - driving a spring reverb tank in lieu of a speaker, with an additional gain recovery/dry mix stage on the output. For reasons I have quite simply forgotten at this point, I decided I wanted to oust the 6K6/6V6 Champ inspired power section with a 6BQ5/EL84 single ended section. So, since I have one underfoot that I can observe directly, I turned to the Kalamazoo Model 1.
<p>
However, while the Champ and Model 1 are of similar class, they are of different pedigree. There were strengths I wanted to combine, and so we launched into hybrid territory.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjT5qAE25vWf6yocF6Ts04pKrhz7iSMcrBaeW2Kj4YA-5c_dhUneXYWucPRS8HLH0JznKbWOVrCVISB9BEk9-rswozgME8Z8DmnSd0-Vit3V37c0RLVRKwpWrdMypDO5FrTroXn6w/s1600/12AX7a.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjT5qAE25vWf6yocF6Ts04pKrhz7iSMcrBaeW2Kj4YA-5c_dhUneXYWucPRS8HLH0JznKbWOVrCVISB9BEk9-rswozgME8Z8DmnSd0-Vit3V37c0RLVRKwpWrdMypDO5FrTroXn6w/s320/12AX7a.JPG" /></a></div>
<p>
Make no mistake though, when it came down to actual assembly I did not consult the gods of audio. I grabbed whatever I had on hand, you know, like the Old Masters did. Pictured above is the initial 12AX7 tube, first stage at high numbers (socket pinout) feeding a preamp gain (dwell) ala 6G15. This returns to the low numbers triode which is wired up more like the Model 1 sans tone control feeding the power section.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjO1bADsZg-1Rxz7nrESTreeRwtKV3Ulc7GmokTK83eBJBlOYWZERxw1V1g03bUDgmqK17TtlUYPb1_sJQ7UQn-yRHY6pxrXfYVq3QgDFw8GIPaILDeYwt1mZUnF-_i4cuL20H3LA/s1600/6BQ5.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjO1bADsZg-1Rxz7nrESTreeRwtKV3Ulc7GmokTK83eBJBlOYWZERxw1V1g03bUDgmqK17TtlUYPb1_sJQ7UQn-yRHY6pxrXfYVq3QgDFw8GIPaILDeYwt1mZUnF-_i4cuL20H3LA/s320/6BQ5.JPG" /></a></div>
<p>
Here it is evident that I am using previously built components, and did not exert a lot of care in cleaning the vestiges of whatever this used to be. It's a 6BQ5 single ended power section now, please ignore any other disarray. AT LEAST I DIDN'T LEAVE REMNANTS OF WIRING!
<p>
I'd like to note that while the power amplifier stage is pretty much lifted directly from the Kalamazoo, the B+ power supply feeding it is a choked configuration more in line with the 6G15. The single ended amplifier stage feeds an output transformer coupled to a spring reverb tank.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguiFMGvA8zVE8w0hqwJtlU3ZZK8TmxhNM41uTfS9Ey54VC9DX_PXI8bQwX7jfHNn2J_nd7BT_zxXQDS6dTqe0dS9GXoVSps5ud94kSycBRXT4WG3jtk3YtLz5XicgF97Ctx7qufQ/s1600/12AX7b.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguiFMGvA8zVE8w0hqwJtlU3ZZK8TmxhNM41uTfS9Ey54VC9DX_PXI8bQwX7jfHNn2J_nd7BT_zxXQDS6dTqe0dS9GXoVSps5ud94kSycBRXT4WG3jtk3YtLz5XicgF97Ctx7qufQ/s320/12AX7b.JPG" /></a></div>
<p>
The return from the reverb tank is seen here, direct coupled to the low numbers side of the 12AX7 gain recovery tube. This feeds a tone control connected to the high side of a mix control to output. High number side is a cathode follower dry feed taken from input jack, which drives the low side of the mix control.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicHCpzC7y8zMWOWrAZssKuKgskhjc8xRmO7oXUfQ4ymYvEp5o9DZEZWipTcMP0nbfQGGWXi096UHx-M8eBtMg_7LgVFCpOmXqrd35fGScdsbMdSmm5ev2VsHsXdbxFeGIs7meURQ/s1600/capacitor-junction.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicHCpzC7y8zMWOWrAZssKuKgskhjc8xRmO7oXUfQ4ymYvEp5o9DZEZWipTcMP0nbfQGGWXi096UHx-M8eBtMg_7LgVFCpOmXqrd35fGScdsbMdSmm5ev2VsHsXdbxFeGIs7meURQ/s320/capacitor-junction.JPG" /></a></div>
<p>
Depicted above is the aforementioned tone and mix controls. Allow me to name off the imbroglio of capacitors, as there is no single photographic vantage point that could make sense of this mess.
<p>
The burnt sienna .03@600 CDE to the left is the DC blocking input cap for dry stage. Grid is elevated ~ 100 volts or so, and this fine capacitor is what keeps that off my pickups (or transistors, opamps, transformers, whatever.. outboard spring reverb will see more duty than just guitar).<br>
The cyan/turquoise .1@400 is the DC blocker at dry cathode follower to mix pot (at right).<br>
The .01@400 Sprague Black Cat is my reverb recovery section coupling cap to tone control. I think this should actually be a .1, that's a mistake (see if you can spot two more amidst these pics!) but I guess I'll leave it be unless reverb return sounds too thin.<br>
The black .01 disc cap is the tone cap from control to ground, doing what it can to shunt ALL my signal away since I botched the coupling size. <br>
The domino mica cap is a 500pf coupler from tone wiper to mix. I figured I would double the 6G15 design of 250pf here, because, well, you know, I like a little bass. Hahaha, apparently this was a wasted effort. I'll revisit this later. We're not done yet.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgxmoDXW1T4YqcYzzRRJsdVoZeYoITbJwOAwUjD5xf1yKGBCYLqcpS94xejktxS_pYsRR61pls-NQQCroJjGApsw3b1MxxID2718uG2LYenJaAYMcJnWjLy73ICJtC_P62kCcajrA/s1600/congestion.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgxmoDXW1T4YqcYzzRRJsdVoZeYoITbJwOAwUjD5xf1yKGBCYLqcpS94xejktxS_pYsRR61pls-NQQCroJjGApsw3b1MxxID2718uG2LYenJaAYMcJnWjLy73ICJtC_P62kCcajrA/s320/congestion.JPG" /></a></div>
<p>
Before anyone pipes up about it, yes, I am aware of capacitive coupling, lead dress and ground loops. Thankfully I'm okay at (read as: used to) working in tight configurations, what with the rework I have in store.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJ71KE2YPOMXPbOAgPs8uXW7VZUOND4dI3DB-WYPSBTY5NQYoWSwrO8sEoN4NfnC0g4Ebev1X7AR3QY8k-pMLCNCqaV2LRV_f68VQqBhdl2y5zJBpCeoflPfpdzadgT31VG-AZ-A/s1600/fit-test.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJ71KE2YPOMXPbOAgPs8uXW7VZUOND4dI3DB-WYPSBTY5NQYoWSwrO8sEoN4NfnC0g4Ebev1X7AR3QY8k-pMLCNCqaV2LRV_f68VQqBhdl2y5zJBpCeoflPfpdzadgT31VG-AZ-A/s320/fit-test.JPG" /></a></div>
<p>
The unit is going to be a controls on face, at bottom type of configuration (ala Marshall heads); so this is the natural finished stance of the chassis. Rear support is not going to be via standoff, it will be supported all sides by wooden runners.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhN59TUtuDa827Y_Z_U0o3TJtsv9hUC9ysDWvGk7AiBiNF1lEoqy_EcHZFX1GqvyjdCpmXe5taq_oRc9X1KT97yFavtc0fVhqebevMfL5Hs7V6oYEKMEBwPV0DjC8KTvE-O2SK5aQ/s1600/topside.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhN59TUtuDa827Y_Z_U0o3TJtsv9hUC9ysDWvGk7AiBiNF1lEoqy_EcHZFX1GqvyjdCpmXe5taq_oRc9X1KT97yFavtc0fVhqebevMfL5Hs7V6oYEKMEBwPV0DjC8KTvE-O2SK5aQ/s320/topside.JPG" /></a></div>
<p>
So, with everything more or less squared away I set about the initial slow warm up on a variac. Something, however, was amiss. My voltages were way off, B+ being abnormally low. Concern with a short circuit proved unwarranted. Everything tested out okay, it was just that my B+ leg was reading roughly 10% of expected.
<p>
I had tested this transformer prior, and it was concluded to be a ~500 volt center tapped secondary. You know, because I measured it. Having the luxury of an uninstalled identical transformer I conducted the measurement test again on a part out of circuit.
<p>
Imagine my surprise when it turned out the high voltage secondary of my chosen power transformer was in fact delivering only ~50 volts across the windings! DECIMAL POINTS MATTER.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzgIZnj_2_pVY1Qrko7yKa_vIjN0pP6Ph6aR0p67-vhSVhJXcaZWkJvUDeFrYQLef_c5bYVGQQG7_6dLoPjjWLfbctl8fp7PuNBp6E82IbUIArVz3rPqrQx_vcxALjsC6n-IGADQ/s1600/tube-base.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzgIZnj_2_pVY1Qrko7yKa_vIjN0pP6Ph6aR0p67-vhSVhJXcaZWkJvUDeFrYQLef_c5bYVGQQG7_6dLoPjjWLfbctl8fp7PuNBp6E82IbUIArVz3rPqrQx_vcxALjsC6n-IGADQ/s320/tube-base.JPG" /></a></div>
<p>
Above is an example of finished fitment, tight gap between the tube and chassis. Too tight? I'd probably bevel that on a production unit, but this is not, so..
<p>
Anyway, I'm wary about trying to fit enough discrete voltage multiplier stages to make use of the 50 volt center tapped PT work, so I'm thinking about piggybacking another transformer in there, either something with a proper B+ right out of the gate, or a step up I can drive with the 50 volts (I think a 120:24 volt transformer may work nicely here). Sadly, I couldn't find a correct voltage range with identical mounting in my piles, so the fix may wind up being less than visually perfect.
<p>
Of course, it'll all be encased in a cabinet anyway. Stay humble!crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com0tag:blogger.com,1999:blog-33019505.post-41884623211465365632013-09-13T06:57:00.000-07:002013-09-13T06:57:05.848-07:00<p>Happy Friday!
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhe83c6wopk8OOTS26ghutCqGd_GZcgv2ejY72z3nJmxWPrsj3RRKA3ckaa9qH3guGW8rMK_cVVnpFZmFcRxEZG6XNZEiWPCDdGoC0UFHdhovh5lIN2eAIN-TmNvTlZs_jlpGA27g/s1600/corrodedIC.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhe83c6wopk8OOTS26ghutCqGd_GZcgv2ejY72z3nJmxWPrsj3RRKA3ckaa9qH3guGW8rMK_cVVnpFZmFcRxEZG6XNZEiWPCDdGoC0UFHdhovh5lIN2eAIN-TmNvTlZs_jlpGA27g/s320/corrodedIC.JPG" /></a></div>
<p>
I know, I know.. elongated lull. Apologies. Expect more of the same...
<p>
..for now.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com5tag:blogger.com,1999:blog-33019505.post-30416986597538174622013-06-16T07:57:00.000-07:002013-06-16T08:06:00.699-07:00After breaking the old Japanese chassis punch set I've had for ten some odd years, I figured I'd have a stab at cheaping out with Harbor Freight to see if I can find something serviceable. Took a gamble with a 91201 ten piece punch set. Something to keep in mind about this set, it is designed around outside diameter of conduit. Allow me to demonstrate:
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhX0hqFMYtDCfk0iQaroXhTgQ98Hq_wiWIqf3HzKyDoaimaYzfl3eZCv6vq4F7fbIQCQZNWvQFbZ3VX0H1s7vIugqW0KyU9cZ_PgGi8wV56-ZDABrmo0OHUyeeTySD-7virvRzp2g/s1600/08835.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhX0hqFMYtDCfk0iQaroXhTgQ98Hq_wiWIqf3HzKyDoaimaYzfl3eZCv6vq4F7fbIQCQZNWvQFbZ3VX0H1s7vIugqW0KyU9cZ_PgGi8wV56-ZDABrmo0OHUyeeTySD-7virvRzp2g/s320/08835.JPG" /></a></div>
<p>
0.5 inch.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6pbJQccKa7iIe_pLyDsbGmaKT3QlipBrYVv7ww8I590KogLA7pZfL4ZkDj0hAYwhIVctulqnWslMu_8DpC5TTySWRBa6BaxtS7LBfcDLbnZkFm-ZGEcK_nh3Y8VBHc2KIVqzj_w/s1600/10840.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6pbJQccKa7iIe_pLyDsbGmaKT3QlipBrYVv7ww8I590KogLA7pZfL4ZkDj0hAYwhIVctulqnWslMu_8DpC5TTySWRBa6BaxtS7LBfcDLbnZkFm-ZGEcK_nh3Y8VBHc2KIVqzj_w/s320/10840.JPG" /></a></div>
<p>
0.75 inch.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglSGC5xXT56ESoGszgodoEfzd5rA71eXdfSbWoFYHmoY7JcD0cr2YMJWtmkooH0m584_EOpwxfwDCwiJu-yFEXEtGTaYamNZluGLqU2SGUPfqxicSvIm9Lf1K7RsBWTfI8pmYK7Q/s1600/13585.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglSGC5xXT56ESoGszgodoEfzd5rA71eXdfSbWoFYHmoY7JcD0cr2YMJWtmkooH0m584_EOpwxfwDCwiJu-yFEXEtGTaYamNZluGLqU2SGUPfqxicSvIm9Lf1K7RsBWTfI8pmYK7Q/s320/13585.JPG" /></a></div>
<p>
1 inch.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjREzirvL26_WvMPRVl0mcxMaLpVRsfWqH8RhAfqVQw7CLHP-LpmDl8VpAP_cs5SA8TLqRVtd4iwUxLxMPQ-wzYVcL6bRlafy8qEve82013M8hSKV9FlbpQkSZI8TWmgKN5tiqx7g/s1600/16925.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjREzirvL26_WvMPRVl0mcxMaLpVRsfWqH8RhAfqVQw7CLHP-LpmDl8VpAP_cs5SA8TLqRVtd4iwUxLxMPQ-wzYVcL6bRlafy8qEve82013M8hSKV9FlbpQkSZI8TWmgKN5tiqx7g/s320/16925.JPG" /></a></div>
<p>
1.25 inch.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgy2clZE5InTA6h2-Mis5Ncvp9gKFm8fJpvakThxhoKnOhWCtfhDPL_AkBhFjrWJVdt7J3vppBeQarz__rqYEF2VS0FSGjvM_1Eh21nxy6rs7RxhFyAj-S1yT69O9Y85EHJ4PE0Cg/s1600/91201punch-side-shear.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgy2clZE5InTA6h2-Mis5Ncvp9gKFm8fJpvakThxhoKnOhWCtfhDPL_AkBhFjrWJVdt7J3vppBeQarz__rqYEF2VS0FSGjvM_1Eh21nxy6rs7RxhFyAj-S1yT69O9Y85EHJ4PE0Cg/s320/91201punch-side-shear.JPG" /></a></div>
<p>
Working into space constraints, I really need a 1 inch hole, going over by 84 mils will put me into breaking sidewall territory, so I grabbed the 0.8835 "1/2" incher with the intent of making up the difference with file by hand. To its credit, it did seem to make a bit more progress before failure.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgKPbSN9AjXp4GuuWtiFjvWE4SnrmzWN8oQ0RyL9kdPDDnnpjvlkXhyJKXWZ9SxbeXN-G8Dm8fR4Tjuv4wnEuqDHC6XkAzxAswrkelzfEsZc1aUexDQ2JO2oqeP_Jqv8BBjPf1TQ/s1600/91201-pullstud-failure-die-side.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgKPbSN9AjXp4GuuWtiFjvWE4SnrmzWN8oQ0RyL9kdPDDnnpjvlkXhyJKXWZ9SxbeXN-G8Dm8fR4Tjuv4wnEuqDHC6XkAzxAswrkelzfEsZc1aUexDQ2JO2oqeP_Jqv8BBjPf1TQ/s320/91201-pullstud-failure-die-side.JPG" /></a></div>
<p>
There are a lot of ways to botch a screw, and I've sheared my share of hardware via the mechanical force of the hardware itself; I do not recall seeing something quite this bad.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFWAtdSZQThVxP-0VXAM4aIjasuzZgBR3MkSOwIGlmjTxiqpDXjYAVJg9iiFPVnzhAbw7LbwsgEZgOElIEKexLGtsE-YE5srR5JEA_tc6YsWQPg4g6v4-zMINxKCGzJE7Ybh-8jQ/s1600/91201-pullstud-failure-closeup.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFWAtdSZQThVxP-0VXAM4aIjasuzZgBR3MkSOwIGlmjTxiqpDXjYAVJg9iiFPVnzhAbw7LbwsgEZgOElIEKexLGtsE-YE5srR5JEA_tc6YsWQPg4g6v4-zMINxKCGzJE7Ybh-8jQ/s320/91201-pullstud-failure-closeup.JPG" /></a></div>
<p>
A little internet sleuthing (admittedly done BEFORE I purchased the tool, so you're all encouraged to laugh heartily AT me) indicates a lot of failure with the small stud, but apparently there's a newer revision that addresses the problem. Hopefully mine is first rev, this level of failure indicates process issue with me.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjY4qgUac3SmnUzkcZtPuQL4VCZPlJDNOpVq77iiDPX3WdoR9_thj5nKInCn_5wjjje2_WyU42b6VqM6neBNUPXrP2uB1icbJe9zlpa4y_d3muyWlAbfEL7idw34W-981gBVOEvCA/s1600/91201-pullstud-shear-faces.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjY4qgUac3SmnUzkcZtPuQL4VCZPlJDNOpVq77iiDPX3WdoR9_thj5nKInCn_5wjjje2_WyU42b6VqM6neBNUPXrP2uB1icbJe9zlpa4y_d3muyWlAbfEL7idw34W-981gBVOEvCA/s320/91201-pullstud-shear-faces.JPG" /></a></div>
<p>
If you're bored and want to read more about this sort of thing, look up "cast iron railroad bridges".
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVnQnuES8oIIuuJlfR4E4eSLxw-DeUIiOkkcst6xl1hgtGOGJVGxCVLGlOFCffnE8OgncbeNsZlImTQmLgIJq95Hmfe0w8Yc5XbWJ77ilqLZzBT3dcEKAc0jhIWpEyIdpTgrd2UA/s1600/91201-crack.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVnQnuES8oIIuuJlfR4E4eSLxw-DeUIiOkkcst6xl1hgtGOGJVGxCVLGlOFCffnE8OgncbeNsZlImTQmLgIJq95Hmfe0w8Yc5XbWJ77ilqLZzBT3dcEKAc0jhIWpEyIdpTgrd2UA/s320/91201-crack.JPG" /></a></div>
<p>
Brittle metal.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhdWFuS88EWwo7aPUrKBxAtHuLKQ1QHDhtkQUcg3dl-qp6H1aR0YnY2lPZg5Cep77sbzNJW4TtCj07_5Hmqt9pt3MC2rNfEzOAti04HitlOr8JvqmIaJsuuO4xBBOWB0hvrZ25tg/s1600/91201-pullstud-explosion.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhdWFuS88EWwo7aPUrKBxAtHuLKQ1QHDhtkQUcg3dl-qp6H1aR0YnY2lPZg5Cep77sbzNJW4TtCj07_5Hmqt9pt3MC2rNfEzOAti04HitlOr8JvqmIaJsuuO4xBBOWB0hvrZ25tg/s320/91201-pullstud-explosion.JPG" /></a></div>
<p>
I've given the stud a bit of scrutiny, and cannot find evidence of material having fractured out of the screw. Thread count matches, and I can see where faces would line up. However, the metal is now highly deformed and the gap will not close when lined up, as if it was under heavy preload prior to failure and relaxed into a state that puts a wide void where thread should be.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEx91_E2J0kBWkQMkhCK__0SmLOuaU613MXNyJCquJs0Ak6EoTeWy2rEo9r-hJwH4PHPOJAXbK5oyFb-Hp7KAdyFQADR7fU6p1I2pKvJtXQ1WxwXiwUQ9yN3cT5A502F_0bW4oSA/s1600/gap.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEx91_E2J0kBWkQMkhCK__0SmLOuaU613MXNyJCquJs0Ak6EoTeWy2rEo9r-hJwH4PHPOJAXbK5oyFb-Hp7KAdyFQADR7fU6p1I2pKvJtXQ1WxwXiwUQ9yN3cT5A502F_0bW4oSA/s320/gap.JPG" /></a></div>
<p>
It's almost as if it's laughing at me.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpFAHGyqFsn_uOyBYyBLydrNyZY6wQ-6qPdhDv38WWkz6vO_wru1iPYXWDzYlsWaTdJSA-XuCzdoJ4wfyF8eaF0SDk7HXR8MvqoHEosfbKsxnfWqsI-NigTG10IQHcFL0srm6Diw/s1600/punch-failure2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpFAHGyqFsn_uOyBYyBLydrNyZY6wQ-6qPdhDv38WWkz6vO_wru1iPYXWDzYlsWaTdJSA-XuCzdoJ4wfyF8eaF0SDk7HXR8MvqoHEosfbKsxnfWqsI-NigTG10IQHcFL0srm6Diw/s320/punch-failure2.JPG" /></a></div>
<p>
The panel is getting nicely chewed up at this point.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmF68yhF2SocE00s7GfSwMptykuozRFh6NXCLvFp8XNZKKR71NXazi4OxJJ9FDtZDaBGHe-XfnQXGdLXIgVzNlxpIVhsH7ai2ihwZn4At2YRDaFsRNLI-1BAgzV2D7hAU41kOXJQ/s1600/closer.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmF68yhF2SocE00s7GfSwMptykuozRFh6NXCLvFp8XNZKKR71NXazi4OxJJ9FDtZDaBGHe-XfnQXGdLXIgVzNlxpIVhsH7ai2ihwZn4At2YRDaFsRNLI-1BAgzV2D7hAU41kOXJQ/s320/closer.JPG" /></a></div>
<p>
Side by side, a comparison of losers. Really though, it's pull stud failure on both accounts, so instead of fussing about with further stupidity I'm thinking of visiting my local reputable hardware supplier and seeing what I can get in the way of threaded stock that can support this sort of load.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgG9grwbIBpouaSLCw5BRymh5fBs6JcdOcN_t-kazUI1Rruu9QLZR5xp6GZUT4NcWBX8lP89Oc3hInwtpLrQ-qqGK9C-cBt-5RQIbF3ZjKyy4KCV8_NIoxGkyjsmyZPCo1WbLGOIw/s1600/chassis-space.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgG9grwbIBpouaSLCw5BRymh5fBs6JcdOcN_t-kazUI1Rruu9QLZR5xp6GZUT4NcWBX8lP89Oc3hInwtpLrQ-qqGK9C-cBt-5RQIbF3ZjKyy4KCV8_NIoxGkyjsmyZPCo1WbLGOIw/s320/chassis-space.JPG" /></a></div>
<p>
In the mean time, for this one, I just drilled it out as high as I can go with a drill (0.875") and made the rest up with a hand file, as evidenced by the bought of scraping situated inboard of the abnormally large pilot lamp assembly.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5gdhzuNqrjmunlYc8lKLfmMnZ9i-m5SbtO4-SbVixiO_jtjdbccLr9zrsmGobj38e5t3UWMB9zx2gBaOPyc8wrbE6O6g9v8gCzmjarpXgcA7Sr0m6ryI1cEQZSs4z8goV38C5dw/s1600/6g15-mockup.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5gdhzuNqrjmunlYc8lKLfmMnZ9i-m5SbtO4-SbVixiO_jtjdbccLr9zrsmGobj38e5t3UWMB9zx2gBaOPyc8wrbE6O6g9v8gCzmjarpXgcA7Sr0m6ryI1cEQZSs4z8goV38C5dw/s320/6g15-mockup.JPG" /></a></div>
<p>
Now that the front panel can support a mock up, I'm free to position the iron for plunging the mounting holes and then moving on to tube socket & various. Thankfully, I'm substituting a 6BQ5 for the 6K6, and I can get away with making a hole to accept 9 pin miniature with the drill press. Otherwise, I'd probably be a bit irate about this experience.
<p>
Also, FWIW, my snap edge is the one pictured on the left, the uglier cut to right being one conducted in field with a circular saw (by others). Thought it crucial to defend my work since that will all be buried in woodwork anyway. HAHcrochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com8tag:blogger.com,1999:blog-33019505.post-44514349427534902932013-06-15T11:06:00.001-07:002013-06-15T11:09:53.901-07:00Set about building a loose Fender 6G15 clone today. Then I got the wise idea of deploying an oversize pilot lamp assembly on the front panel.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjv60KXK5kH6FAEm5-ZY0s90LuJtB37VYwsUgbI-Up4Dy4ARiaE5j7N7WVf1wZd3S3llYpEI_lgbERvVALicTz32pJ-TIgTf5M9gRXVd8THb_8kcHk1ndUP2uZ76HYjtfi_82RFnA/s1600/chassis-punch-broken.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjv60KXK5kH6FAEm5-ZY0s90LuJtB37VYwsUgbI-Up4Dy4ARiaE5j7N7WVf1wZd3S3llYpEI_lgbERvVALicTz32pJ-TIgTf5M9gRXVd8THb_8kcHk1ndUP2uZ76HYjtfi_82RFnA/s320/chassis-punch-broken.JPG" /></a></div>
<p>
Sometimes good ideas end in tears.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwfYVdwDIyNPQ57GHbHwt1PlS8lTi-FqxLlZx01QoU1_aC0f4oHVGOXV89E1EhT0_y_TG7I1AVRfe61yhMRQxowOqKkJqo1Rad3w9z8CYhAM1sPJkszi3aFDIvgC95B47SIvsHRw/s1600/borken-punch.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwfYVdwDIyNPQ57GHbHwt1PlS8lTi-FqxLlZx01QoU1_aC0f4oHVGOXV89E1EhT0_y_TG7I1AVRfe61yhMRQxowOqKkJqo1Rad3w9z8CYhAM1sPJkszi3aFDIvgC95B47SIvsHRw/s320/borken-punch.JPG" /></a></div>
<p>
Clearly there wasn't a whole lot of steel connecting the threaded draw stud and the die assembly, I was having a hell of a time pushing the punch through (bending metal was involved). Apparently 8 gauge alumin(i)um is beyond the capacity of this instrument. The instrument in question being a "vintage" (it has a wooden box, no idea on era of manufacture) multi punch set of Japanese manufacture.
<p>
I also felt a little elation at rediscovering the root of the word "borked", typographical error in my naming of the file "broken-punch". Sure, this may be in error, but I'm going to demand you allow me this silver lining and refrain from dashing my bit of feel good until you see a pic of the finished panel, thanks!
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhK6PhlIRqfp9fawJFsinf3xRp_c-7DkWe18PLioivvjBoO28K0yynacJEGB5CuYUYVmPqMHzrLtVCLu34ITrEabIACXsuwsOp8K0At4FZ6RdGPnfniil0d_u32Unf6hdIgzlRD9Q/s1600/too-much.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhK6PhlIRqfp9fawJFsinf3xRp_c-7DkWe18PLioivvjBoO28K0yynacJEGB5CuYUYVmPqMHzrLtVCLu34ITrEabIACXsuwsOp8K0At4FZ6RdGPnfniil0d_u32Unf6hdIgzlRD9Q/s320/too-much.JPG" /></a></div>
<p>
So close. I figured I was at about the initial shearing point where actual force involved drops dramatically, which was good, as this was proving to be a PITA to punch by hand. Then the force required to turn the screw dropped like a rock.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7-Hp9jhgoJ4lkwfcZkgpUdL4SwpHFtJYsjc_X2-q7ternmAHy_c7cyThV1v_AYZFikmv1ZIcYdYdCzddico70RpFLn6b9MrZZbIvdoQfr03jRNowQlg3bYqq1X0euiyPImCoHuQ/s1600/impression.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7-Hp9jhgoJ4lkwfcZkgpUdL4SwpHFtJYsjc_X2-q7ternmAHy_c7cyThV1v_AYZFikmv1ZIcYdYdCzddico70RpFLn6b9MrZZbIvdoQfr03jRNowQlg3bYqq1X0euiyPImCoHuQ/s320/impression.JPG" /></a></div>
<p>
Well, I've got an idea of where the hole *should* be.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0n3jVyCdOOJR3SforOUoXdYexX-9dRP6u6164cQxJIwRQUniwevEdfH0zx9w0V-fU9_Ce1sMiGHQldmZKDGMuUQIo0lVNBgtlFl5VCaYLFNde8xNK6xV9mcO6Oydbex7fU3Ipyg/s1600/deformity.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0n3jVyCdOOJR3SforOUoXdYexX-9dRP6u6164cQxJIwRQUniwevEdfH0zx9w0V-fU9_Ce1sMiGHQldmZKDGMuUQIo0lVNBgtlFl5VCaYLFNde8xNK6xV9mcO6Oydbex7fU3Ipyg/s320/deformity.JPG" /></a></div>
<p>
Pretty sure this won't accept the 1 inch lamp body though.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmb6zqEalb2Aac8QmGvRX3NyTj5uyjnTyOolaaxCgiNaX8lsCJUALlRX4a00LOR3tV3PDUq2D1TEaAWu6f_UwW-S8cOgMIjA3VOLwUka5lwq0rkQuuYWZ349E4fVzHO-GXQA2Ajg/s1600/scroll-saw.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmb6zqEalb2Aac8QmGvRX3NyTj5uyjnTyOolaaxCgiNaX8lsCJUALlRX4a00LOR3tV3PDUq2D1TEaAWu6f_UwW-S8cOgMIjA3VOLwUka5lwq0rkQuuYWZ349E4fVzHO-GXQA2Ajg/s320/scroll-saw.JPG" /></a></div>
<p>
In other news, the scroll saw handles 1/8th inch 6061 (I think) just fine with a 10 tpi (Delta 40-193) regular tooth blade. I went super easy on the feed rate, and ran into no problems. I'll be having a go at using the chop saw as soon as I find a sacrificial 10 inch blade (not my fine finish framing blade).
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUtqVK7Eo4OVPyt_l4Q_my6XZJZYic5TAIpY99PQWYr7_PfPYUFC_mlysg2QJBZzGpIU6LIBtrmOkUmckXgaezrunb90fYbyL-6VBa2gedSqRzIPuDkkXbiIXRRlKUnqU9lbO_aw/s1600/break.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUtqVK7Eo4OVPyt_l4Q_my6XZJZYic5TAIpY99PQWYr7_PfPYUFC_mlysg2QJBZzGpIU6LIBtrmOkUmckXgaezrunb90fYbyL-6VBa2gedSqRzIPuDkkXbiIXRRlKUnqU9lbO_aw/s320/break.JPG" /></a></div>
<p>
I did flinch a little at running completely through, but scored as such and with a quick swipe of hacksaw (before deciding to give the brute force method a go) the material snapped pretty well. This is where the metallurgists may pile in and inform me the 6061 is wrong. The extrusion is surplus from seismic joint assemblies, it's either 6063 T5, T6 or T52; 6061 T5, T6 or T51; 6105 T5 or T6, 6005 T5, 6005A T5 or T61, according to current manufacturer datasheets. Anyway, I've got plenty for now, it's nice and thick, and will be turned into stuff that is not part of a building.
<p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdO6lXF_IUcTuC7kF-sLDRkAhXlTIGN_LaBiH5sz_LsJzMKYi6aKWHzP_61YidxmkxUpoLSgVpv0E2uj0k74u1ekhvIVTpSWQoNfJBhZWz2Be_-kXn6GebV6Glt-UYCjI3bo1z4w/s1600/pilot-lamp-enclosure.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdO6lXF_IUcTuC7kF-sLDRkAhXlTIGN_LaBiH5sz_LsJzMKYi6aKWHzP_61YidxmkxUpoLSgVpv0E2uj0k74u1ekhvIVTpSWQoNfJBhZWz2Be_-kXn6GebV6Glt-UYCjI3bo1z4w/s320/pilot-lamp-enclosure.JPG" /></a></div>
<p>
In the end, I think this oversized pilot lamp will be worth the effort and headache. In the meantime, in looking at the going rate of Greenlee punches (taking into account the variety of sizes I need) I'm thinking the path of least resistance is to fix my welder, fix this punch and tough it out until I finally get around to completing the CNC build (Couple years? Sooner? Later? Time will tell, taking bets now... ).crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com0tag:blogger.com,1999:blog-33019505.post-74078395507964720452013-06-03T08:05:00.000-07:002013-06-03T08:20:50.418-07:00It's high time I commence working on enclosures. To assist in this endeavour is a new to me Craftsman 103-23100 benchtop drill press that evidently hasn't seen much use in a while. This is replacing a Harbor Freight special that essentially boiled down to a nightmare of radial slop. I could plunge a neater line by hand, but I digress.
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJiu3HMmBQA0nXVNRSVOrRhd-U1oHIAkpifJinYY82LkQfDShm_RON6vDJTyam5rkn7p7t7ZAwxjE3bH3cpWsYrtI__QC_L8RHQ0Okj_2xTcdNiBY3SFRyTM6O5HVexaasL-f-UA/s1600/103-23100main.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJiu3HMmBQA0nXVNRSVOrRhd-U1oHIAkpifJinYY82LkQfDShm_RON6vDJTyam5rkn7p7t7ZAwxjE3bH3cpWsYrtI__QC_L8RHQ0Okj_2xTcdNiBY3SFRyTM6O5HVexaasL-f-UA/s320/103-23100main.JPG" /></a>
<p>
I'd much rather talk about stylized mid century domestic US steel than the resulting product of decades worth of exponential bean counting. Make no mistake, it may be manufactured in China, but those cheap tools are American products. Apologies, that's just my Monday morning cheer shining through.
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYdvzLBr8tAX1y70zC6RVDChlOqQZVaZazRDj8r5Dbqj0MLyKVuvZMJh2B__zvPo24gHhqyjmELRDRhZO9OUKlzuIh6laSwn2A0jIIJLT5rWDIZ1hDwe1ujPiBR0VBEck0gMtF-w/s1600/MarathonACmains-inlet.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYdvzLBr8tAX1y70zC6RVDChlOqQZVaZazRDj8r5Dbqj0MLyKVuvZMJh2B__zvPo24gHhqyjmELRDRhZO9OUKlzuIh6laSwn2A0jIIJLT5rWDIZ1hDwe1ujPiBR0VBEck0gMtF-w/s320/MarathonACmains-inlet.JPG" /></a>
<p>
The prerequisite visual inspection indicates a little work is in order. While the angle of shot does not reveal it well, I can report that both legs of the early cloth covered AC mains wire have slipped their insulation at this point.
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4jejOoie-ZBIXEYVJoTSWaqwhx8WfLeIN_623iv28y0sPnYeJs2QdN5DmfA0us3lsC6ahXrydmt4Ns6rxCNgwEqviubebNk286yLgJu4m0zc0_AguEfbb6-4HKZ93yRNWaVouIQ/s1600/square-nut.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4jejOoie-ZBIXEYVJoTSWaqwhx8WfLeIN_623iv28y0sPnYeJs2QdN5DmfA0us3lsC6ahXrydmt4Ns6rxCNgwEqviubebNk286yLgJu4m0zc0_AguEfbb6-4HKZ93yRNWaVouIQ/s320/square-nut.JPG" /></a>
<p>
I think the motor is not original, the bolts however may be.
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVsKHLCRlZrQv-I6P7sHcmdUGLeqhnEw-O_kxm0eIR3jbJi8TI-tOwpSSg4v2kL1vzYWPJWputpHcz1W7K3YlU3TC2j4xrokj5EAHbA1WGvLKe2GiIBqryS1eix7uYpW_m5f58CA/s1600/square-bolt.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVsKHLCRlZrQv-I6P7sHcmdUGLeqhnEw-O_kxm0eIR3jbJi8TI-tOwpSSg4v2kL1vzYWPJWputpHcz1W7K3YlU3TC2j4xrokj5EAHbA1WGvLKe2GiIBqryS1eix7uYpW_m5f58CA/s320/square-bolt.JPG" /></a>
<p>
I'll make sure to evenly distribute those washers upon reassembly..
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfq6KY5KKuMv_FtNCiRWN1ShNRVBjYGyYCfDkZ3rJ4MmhcuLQ3yfMZP8gHcrW7V3vY7GVNA9QsNsu2uBHB89JzIqER8iWsbww6IbbStHRbv7jIhNKlR_G6mCx-nEjvpOxKeoL1hg/s1600/Marathon-AChousing.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfq6KY5KKuMv_FtNCiRWN1ShNRVBjYGyYCfDkZ3rJ4MmhcuLQ3yfMZP8gHcrW7V3vY7GVNA9QsNsu2uBHB89JzIqER8iWsbww6IbbStHRbv7jIhNKlR_G6mCx-nEjvpOxKeoL1hg/s320/Marathon-AChousing.JPG" /></a>
<p>
Removal of the AC access plate indicates some years of use as a wood working tool.
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgs3-0l_rK2I13zUQ1txayF5NeJOT5ccYcRud2dLDs8xN0zNKn1eI_hqcQnfhznYh1ID0nSTzEryMt64F31SMeXnAw0pP_3K1ASwa-zx7UbiXm6T-ps8FXjvjMitBpF3HIiD-m1nA/s1600/wood-pulped-electrical.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgs3-0l_rK2I13zUQ1txayF5NeJOT5ccYcRud2dLDs8xN0zNKn1eI_hqcQnfhznYh1ID0nSTzEryMt64F31SMeXnAw0pP_3K1ASwa-zx7UbiXm6T-ps8FXjvjMitBpF3HIiD-m1nA/s320/wood-pulped-electrical.JPG" /></a>
<p>
Not high tech, but the installation outlasted the wire itself.
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-deGZB1d3V5KwCDpOc3ZgfPbRPZv2uYgobpSMYJv2kD34HkzMlnNyTL4mzj4XdatEgsvEzQoLJq-MomUjAabXIjK2yvu3RPGS5WFnlVuk5GPIvFQTB-ZO2Hu_jlhSEtQybEnn8w/s1600/mains-stud.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-deGZB1d3V5KwCDpOc3ZgfPbRPZv2uYgobpSMYJv2kD34HkzMlnNyTL4mzj4XdatEgsvEzQoLJq-MomUjAabXIjK2yvu3RPGS5WFnlVuk5GPIvFQTB-ZO2Hu_jlhSEtQybEnn8w/s320/mains-stud.JPG" /></a>
<p>
There's a little black smudging on the soldered joint about an inch back from the stud, I'd like to know what's been going on here before putting the motor back into service.
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCko9OlRMGqDsU_x1uagqg176MKHhv-0KJGKCj1zGyrqjvOTSooq_9R3nJOOeNxhW-aGjBIyvCfebGdHldHQiU0osj6apYJS4oTtEQ2IvBiR3MJ4n0ATDro0j8o1uS5Pzxl5C3rw/s1600/scorched-wire.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCko9OlRMGqDsU_x1uagqg176MKHhv-0KJGKCj1zGyrqjvOTSooq_9R3nJOOeNxhW-aGjBIyvCfebGdHldHQiU0osj6apYJS4oTtEQ2IvBiR3MJ4n0ATDro0j8o1uS5Pzxl5C3rw/s320/scorched-wire.JPG" /></a>
<p>
The corresponding point in the wire...
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnAyJ0lTEPPqapzCIz4jql9QJF0HwWoofotajgvmP0RHEzsV3p37QYAOrchb1G949KtFYoSW-hxPnp73VmL4ir68D3oXC1ZX9yPmjDSxiFQT2SZlwSMfVgRuXwf0c8BW3f4Lzv5g/s1600/insulation-failure.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnAyJ0lTEPPqapzCIz4jql9QJF0HwWoofotajgvmP0RHEzsV3p37QYAOrchb1G949KtFYoSW-hxPnp73VmL4ir68D3oXC1ZX9yPmjDSxiFQT2SZlwSMfVgRuXwf0c8BW3f4Lzv5g/s320/insulation-failure.JPG" /></a>
<p>
...supports the theory that the insulation failure coupled with a conductive path of oily wood dust provided a high resistance path that could heat up with use. Or, perhaps it's just an oily spot. Either way, the motor is functional and intact. My elation at having an operational piece of equipment is evidenced by the fact that I clearly leaned forward a sixteenth of an inch while taking that photograph.
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgH9dSPO4a7z_XhWajh2aGW9tTvMq4xpXEy9sPMKr8bcwRskBtNKSa_SxUHDwBx3QVGyZ2dc7HSo9j3TMHfg1a73ShocFGJFbPVV5Ks_E7eUaHm6ZNkcNEYZNAgUkFWkjsSXuXRyA/s1600/new-grounded-lead.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgH9dSPO4a7z_XhWajh2aGW9tTvMq4xpXEy9sPMKr8bcwRskBtNKSa_SxUHDwBx3QVGyZ2dc7HSo9j3TMHfg1a73ShocFGJFbPVV5Ks_E7eUaHm6ZNkcNEYZNAgUkFWkjsSXuXRyA/s320/new-grounded-lead.JPG" /></a>
<p>
New wire snaked into place, now with a chassis ground.
<p>
While operational, I think I may have to dig into this one deeper, as the rotational assembly seems to exhibit more resistance than I would like, while the vertical travel is as lubricated as a ■■■■■■ ■■■■■ and will drop the drill via gravity feed unless I adjust tension to the point where I can no longer gauge the feel of the drill.
crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com1tag:blogger.com,1999:blog-33019505.post-20138647227280675292013-05-05T13:17:00.002-07:002013-05-05T13:17:50.316-07:00Slow year so far on the repair/build front. I guess slow is the wrong term, disjointed.
<p>
It has actually been pretty busy, I just haven't got a lot to show for it just yet.
<p>
Anyway, I had deep sixed my Roland D-110 about ten years back because it started to power reset itself at inconvenient moments and generally became wholly unreliable.
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8-L5Uug0STqMo5TAJln9fM_Ew5gYKa9x2rnhKMDU6YbThoPp2u-h4gvRBYF0ubtlzfyRmg2v2qnidH8RwHSLMKxOfUdXp_fTGd1XFjQg60kn9ldVKZY7h7YZb-pM7deSASv1y-w/s1600/D110guts.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8-L5Uug0STqMo5TAJln9fM_Ew5gYKa9x2rnhKMDU6YbThoPp2u-h4gvRBYF0ubtlzfyRmg2v2qnidH8RwHSLMKxOfUdXp_fTGd1XFjQg60kn9ldVKZY7h7YZb-pM7deSASv1y-w/s320/D110guts.JPG" /></a>
<p>
That problem was remedied by reseating all the ribbon connectors.
<p>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFjlebRNJyZgDbAGxIQ_BuvzCqEflURiNeei3wQrl81XI5X3-ZHgNLzxgN0RxZAIdPRMEny4P-iFtSy-zJ6IeVTNiDl_NU67UA3xIGevKvKn4eSQS5_hJ8yYG_8-BNICx3wnmgyA/s1600/D110screen.JPG" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFjlebRNJyZgDbAGxIQ_BuvzCqEflURiNeei3wQrl81XI5X3-ZHgNLzxgN0RxZAIdPRMEny4P-iFtSy-zJ6IeVTNiDl_NU67UA3xIGevKvKn4eSQS5_hJ8yYG_8-BNICx3wnmgyA/s320/D110screen.JPG" /></a>
<p>
Memory had also became shot, which has been corrected with a fresh CR2032 in the clip. Unfortunately, when memory goes into a void, everything seems to be reset to the parameter setting least likely to produce sound, so I have to run through and change just about everything in order to get a starting point.
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Yeah, yeah, yeah. I can just data dump factory presets. Sort of takes the magic out of scratch building the sounds. Cheating. I'm now hunting for the long neglected PG-10 to assist in ground up construction of the algorithms.
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So yeah, poor thing sat for ages awaiting a ten minute fix.crochambeauhttp://www.blogger.com/profile/12809007565940847641noreply@blogger.com1