I doubt C2 and C11 would be the culprit. I'd be looking at C3 through C7. It could be that the traces are corroded, preventing proper electrical flow. For that, you can start by tracing out where each connection on C3-C7's pads go. IIRC, the negative side of those cap's pads connect to chassis ground and the positive side may go directly to the pins of UB10 and UB11. So, go grab a continuity tester (one that will give a steady tone when the circuit is closed between the probes (aka traced). Once traced, you can take either enamel coated magnet wire or small gauge stranded wire to act as a bypass for the connections.
Another thing would be to try "pulling up" the sound chip UB11. To do that, solder a 1 kilo-ohm resistor (watts doesn't matter) between pins 7 and 15. The pins on UB11 are numbered counter-clockwise. Pin 1 is closest to the small dot on top of the chip and on the notch's side.
If those fail to fix, you might have to replace the Bourns network filter (RP2). You can get replacement RP2s easily from off of dead Mac SE or SE/30 logic boards; they both use the same part number. You can also build your own: http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html#NoPointer.
Regarding the most recent post for this thread you wrote, it sounds like it could be this. But before you go replacing parts, try resoldering those parts located on the analog board. Over time, heat and age can cause cracks in the solder, giving you the symptoms you are experiencing. Resoldering can be the cheap, easy and permanent solution. So try that first.
73s de Phreakout. :rambo:
Another thing would be to try "pulling up" the sound chip UB11. To do that, solder a 1 kilo-ohm resistor (watts doesn't matter) between pins 7 and 15. The pins on UB11 are numbered counter-clockwise. Pin 1 is closest to the small dot on top of the chip and on the notch's side.
If those fail to fix, you might have to replace the Bourns network filter (RP2). You can get replacement RP2s easily from off of dead Mac SE or SE/30 logic boards; they both use the same part number. You can also build your own: http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html#NoPointer.
Regarding the most recent post for this thread you wrote, it sounds like it could be this. But before you go replacing parts, try resoldering those parts located on the analog board. Over time, heat and age can cause cracks in the solder, giving you the symptoms you are experiencing. Resoldering can be the cheap, easy and permanent solution. So try that first.
73s de Phreakout. :rambo: