MIMF

Have a Taylor guitar in for repair that has the ES2 preamp. The pots are shot. They are Alpha 9mm but special order hence I can find any. Anyone got any spares? They are Model number. 3RP/0901N, Shaft code. C, Style. A, Dim “H”. 2, Taper. B, Value in Ohms.10K, centre detent - https://www.alphapotentiometers.net/9mm ... pot_1.html

Having a look at the board because I am curious, 6 op-amps and a charge pump for the negative rail - all reasonable, but I spotted a quad differenitai comparator and a quad bilateral switch on the board too.. anyone have any ideas that that's about? Just curious.

The circuit might be less forgiving for switching on and off, creating DC offset on the output and loud noises when switching on power. So they might have made something to disconnect output while the supply rails are switching on. Without seeing anything else, that would be my guess. I think it could be done a heck of a lot simpler (a transistor to short the output, and some kind of timing circuit with a cap), but the more elaborate circuit might safeguard against more failure modes.

Wrt the potmeter, maybe accept that they do not have center detent, or can you get the pots?

I had wondered that but it is a lot of circuit. The other thought I had after posting is a compressor perhaps with fixed stages.

My client will take no detents but even then I can't find anything at may of the usually stockists..