Conducive to the process is letting myself be bothered by say, the minutia of stray LEDs in a container of disc capacitors..
..while not being bothered by sifting anything not immediately electronic to a random hardware box that will itself be sifted later.
It's like panning for gold..
..only instead of gold you find rusty paperclips (pro-tip: throw this sort of stuff away).
1st box bent. 2x4x0.75", seems a fitting enclosure to a LPB-1 clone, really can't have too many of those around. I'm really not trying to embrace the steam-punk look, but I'm not NOT trying to look like steam-punk enough to deny that knob, I foresee occasions, due largely in part to my methods and materials, that the steam-punk aesthetic will be a basis for comparison. In much the same way my oils are steeped in comparison to Jackson Pollock. Best to not be bothered with it.
1st box has some pretty organic lines, the corner stresses do contribute to this.
Pre-punching the corners with a small drill on the second box really hit the spot.
The second box may house the SN Voice I haven't completed in far too long. The variety of knobs are there to fuel my thinking in regards to which way I want to go. If I had eleven of the one at lower right I would be set! My line of thinking is to route a wood plank base to drop the metal enclosure on, end ears will be cut longer in the (near stage) future to sink into slots cut into the wood, which will tie into hardware holding everything together.
Measures in at roughly 9.5x4x1". I did take to hammering a bit which takes away a bit from the crispness of the lines. Once I get the primary bends sorted I will work in tab bends to clean everything up, that said, I am liking the Mad Max look..
I wound up with enough metal stock to bang out roughly sixteen of the smaller enclosure and eight of the larger for $4.50 US. Economical build tactics.
Not a whole lot going on in here yet. I will be experimenting with double bent sides shortly.
Looks like I have a good reason to really start thinking about a DIY spot welder. I have some iron that could probably be rewound to provide for the sort of current required (yes, I realise that rust has to go before that's really a doable thing).
Another design tactic I need to sort out is how to retain the patina without the mess. I like the rust...
I can fully appreciate why others may not.
A span of time in which lubricating oil skins over and becomes a tacky varnish has passed since this thing was used last.
We're a bit beyond waxy build up here.
I really don't grasp what would inspire someone to lubricated EVERY surface of something. Perhaps there was a spill...
...cleans up fine with a razor though.
I think I still need to work on adjustment, polish & cleaning due to the chew marks around the bend. Of course, this is a piece of 16ga aluminium and the tool is rated for up to 22ga, so stressing may have contributed.
At any rate, it'll be nice to bang out full custom metal enclosures. The plan is to dig through the weathered sheet stock come Monday. I prefer the look of it without the protective shroud, but I'd hate to get my beard caught in those tacky wheels while bending something (all functions run simultaneous).
Somewhat major streamlining & redesign going on with the CNC build project due to a more in depth level of milling than I had previously planned for.
Over all build quality is looking to go up while material consumption (at least on the framework) is looking to decrease.
Of course, nearing completion on one stage just paves the way to contemplation of the next.
I recall at one point thinking the DIY route to a milling machine would prove the most inexpensive path.
What I had not fully taken into account is that when buying something one piece at a time, the climbing cost of incremental increases of quality is less immediately apparent.
Having drawn that qualitative line in the sand, holding to anything less seems foolish; but for a production push the potential reflected costs of the remaining elements are a factor I cannot overlook. In so far as this is an educational experience, the bang for the buck ratio remains pleasantly generous.
A very clean representative. This unit appears to have come from the same place as the 950...
..which appears to have been a much nicer place to live than my first 488, seen here posing with a can of beer for scale. Essentially, the electronic switch was a budget driven solution to a dual trace oscilloscope. At the output on lower right alternates signal from the two inputs at left, the center "Positioning" control defines a baseline DC offset between the two input channels, so when viewed on an o-scope the two signals could be be distinctly separated on the Y axis. The two rightmost controls define range and speed of switching.
The 5852 seen here (as found) is sitting in for a 6X5 (as published per schematic). The 5852 has a higher filament draw, which concerns me as I have experienced power transformer failure in the EICO HF-81 (which was notoriously under designed) and this has established a tip-toe level of respect for EICO power transformers (that should read "power transformers in general").
All blue wire. I'm guessing this is a kit build. Take note of the long, silver .22 μf cap that is straddling the guts...
That cap is an add (as found), and while this unit is the third 488 I've had the pleasure of meeting, it is the first that already had that cap in place. Observe the schematic above care of BAMA. At upper right is the oscillator section that drives one channel into conduction while clamping the other (bias modulation driven by the second 12AU7 tied to the cathode/suppressor of the following 6AU6s), C1-6 define the ranges. In my "modified" unit I've replaced C1, 2, & 3 with values that do not match the counterparts of C4, 5, & 6 providing a lope to the signal, but I digress.. According to the schematic, illustrated at upper right, the plates of both 6AU6 are unified at B+ and tied directly to the signal leg of the 488 output.
This equates to 270 volts DC at the positive output leg in a stock & unmodified unit!
The blocking cap is crucial here, and I was delighted to see it in place. The EICO 488 is a fine example of why I observe and measure old equipment prior to deployment into the studio. The unit itself can output some semblance of a square wave with the positioning control adjusted to offset DC baseline between the channels, but the fun occurs while feeding it audio as well.
There remains switching noise which I have an idea on but have yet to implement.
Every minute spent on the internet is a minute that I am not pushing this into being. This is the sort of under breath muttering the passer by will hear from the apparently distracted bearded individual as he bicycles to and from work today.. tomorrow... etc.
Seeing as how most of my work is direct to two channel, this wasn't a high priority and it rotated into the pile. I estimate it's been close to ten years since it was used, and it would be nice to have operational again.
Naturally, a little clean-up is in order.
Being that there remain some hours on the heads, this is all worthwhile.
Fpup indicated a while back that these things are dead simple to work on, and if I'm lucky it's a thrown belt. Tear down is indeed simple, I don't know whether to be glad or mortified at how easy the tape path pulls apart (without tools or the nuisance of threading).
Evidence of an extreme alignment issue, I'll have to pay it heed once this is reassembled.
I didn't test fit the guide rollers for cross compatibility, but they do look to be the same shaft so mind the order.
This is more or less exactly a condition as described by fpup. Correction is an easy task, as this is all just press fit (leaning on mortification now, thanks). Correction the take up reel tensioner doesn't do anything to turn the capstan though, so I've got to dig deeper..
The rear circuitry is contained on two PCBs. The upper of which is on a hinged frame that will allow access.
There's a decent photo essay (though it's a single composite image that is very tall) in the service subsection of the MZE Electroarts Fostex R8 page regarding path of access & disassembly that I've essentially ignored completely here.
I remounted the belt, fired the machine up and observed positive capstan movement. Success was brief, however, as the belt jumped in short order. Looks like a rubber order is in my future, now the question is do I dig into other tape transports to consolidate (possibly delaying this fix while I hunt for specific machines) or do I just fix this one to determine my buying experience.. I'm leaning on the latter.
Been without a bridge for my bench for far too long, I understand this will also perform capacitor leakage tests at high voltage, which is nice since I have a few old caps that are in unknown condition.
Turns out the tight fitting box it is nested in is more or less correct, also included was the 950B operations manual. I wonder if this was an early B revision that was using up old faceplates, or if something else was afoot.
Thankfully the tag was fresh enough to remove with little effort, there is a bit of a patina loss where the tag was situated, but I can live with that.
I found this thread outlining a failure mode that happened to two different people, in perusing the manual I note mention of moving slowly with certain controls. I like stuff that works, so I will read, understand and heed these warnings (even if it sounds like we're looking at a design flaw of the unit).
Guts! Pretty clean work for a kit.
