Maybe besides the general question “what could be the root cause” some more detailed questions, which might support me to localize step by step:
– are there any diagnosis options I can use? I guess no since there is no interface to get diagnosis information out of the chip?
– From the information provided above, does this rather sound like a problem coming from the chip part of the mod or from the filter control or the pitch bend control? I’m asking because I fear I have to de-solder all parts of the mod step by step to isolate the root cause.
– Assuming the root cause is the chip: from the information above, is there a certain part of the chip more likely to be the root cause? I’m asking because the soldering points all seem to be when then synth is turned off, so it will be hard to find a solder strap that is appearing “dynamically”. If I could locate at least a certain area to look at (i.e. because the pins there control related functionality) that would make life easier.
– Any ideas how to find potential solder straps that are none when the synth is turned off? Else than an optical search?