Vintage Simmons Drums (UK) Users Group

Has anyone else experienced the follow issue with their SDS8? The "noise" function seems to spill over into all channels while in factory mode. Also, when you switch channel 5 (low tom) over to user defined, it seems to kill the noise function completely and on all channels. Switch it back to factory mode and the noise function returns, but on all channels like before.

I did a quick visual inspection of the board and found nothing obvious like burned out components. Is this a common issue with the SDS8 as it gets older? I do have a factory schematic and do have some basic electronics knowledge and can solder well. I'm 3 for 4 on repairing older Simmons equipment (2 SDS7 repairs successful, a Hihat card conversion successful, but one failure....my SDS9, which I gave up on and sold off for parts or repair.)

I guess what I'm asking is where to start looking for issues? Is it in the noise generation circuit, the 3372 chip, a common diode, cap, transistor or resister in a certain circuit, or in the "latch" circuit I should be checking?

To me it sounds like a circuit is "stuck" or "cross talking" when it does this, which is all the time.

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The hand-drawn ones ARE the factory schematics !

Only later on did they do lots of work using CAD, and even then there was still the hand-drawn stuff...