Stumbled on a cut-away for a precision multi turn pot.


There's a car that rides in the gap between the adjacent coils of the wire wound resistive element, I believe it houses or provides alignment for the wiper.

In other news, the Peavey Mark IV was put to test on a speaker load. After a minute or so of fantastically textured white noise it passed signal well. The floor noise diminished with use, isolating the cause of the noise is on my to do list.

Ground Control, we have a problem.


In June of 2009 I purchased an early Grass Instruments S4 on eBay, well aware that it was in operational disarray. The seller simply tossed the open chassis into a box full of peanuts and dropped it onto a loading dock. Less than ideal shipping aside, I think that the majority of problems with this unit actually stem from poor storage. Which is the only reason I can comprehend for the fluorescent tube shards I've had to pick from its somewhat tacky guts.



Another selenium stack awaiting surgery, I think this makes five awaiting passage over the bench.


However, the interesting puzzle is nested in the wire wound precision potentiometers.


The resistive element is severed, rendering the pot useless. I have another wire wound pot that was floating around a parts bin with the same mode of failure, easy to spot the weak point of the design. With this unit, seeing as how the failure is nearly at the end of the travel, I'll probably take the easy way out and bridge the gap. The break in the parts bin unit is more centralized, so I expect a bridge would deliver an audible step. I'll continue to contemplate my options on that one.