SOLVED BlueBreaker squeals (sometimes)

[spi]

Hi,
Sometimes when I toggle the BlueBreaker on it sounds fine, but if I toggle a few times it starts to squeal. If I unplug power, usually it'll stop, but then will repeat later.

I captured a video of this in action:

VID_20210131_153836410.mp4

MP4 File

1drv.ms

Does anyone have suggestions on how to debug this issue? Anyone encounter similar issue before?
thanks

 

[spi]

For an internal pic, see this thread:
Blue Breaker & Crunch Captain | PedalPCB Community Forum

 

[spi]

I think I fixed it.
Today I opened it up and poked around. Touching one of the electrolytic caps (C9, which appears to be a power filter) was enough to set off the squeal.
I thought maybe it was a cold solder joint, but none of my attempts to remelt the solder made it better.
I decided to replace the cap--had a heck of time getting it out. Finally got it out, but ruined one of the pads. So I installed a new cap on the opposite side of the board.
Boxed it back up and so far so good.