DD-2/3 repair notes

[laurie]

One side to ground.

[At0m49]

Purple wire reading: 4.89v
Black (gnd): 0v it's literally gnd with gnd so...

[laurie]

Ok. All good. Sometimes the +5V supply has issues on these, so that is now ruled out.

Can you confirm the board looks like this:
.

Img_9231edit.jpg (210.07 KiB) Viewed 14056 times

[At0m49]

Yes, it's the same, it's a boss dd3a 1997

[laurie]

I've spent about an hour looking at the schematic trying to figure out what could be causing this fault. I've come up empty. Perhaps it is a memory chip failure? I've never seen this fault, and it doesn't seem related to any of the usual issues in these pedals.

At this point, if it was on my bench I'd use an oscilloscope to see what is really going on.

If you don't have access to a scope, the only suggestion that I have is to tweak the trimpots and see if that makes any difference. Almost certainly it won't, but it is something to try. Use a marker to mark the original positions.

[At0m49]

Hey Laurie, thank you for your time.
I do not have access to an oscilloscope, but maybe some one can lend me one.
I have already tried to tweak the trim pots but the only thing that changed was the frecuency of the parasite sound hahahah. Is there any other suggestion?

[laurie]

Happy to have tried to help. At this point I can't see any way forward without a scope.

[At0m49]

Let's say that I got a scope, how should I test the pedal?