So about a month ago while sitting in attract mode for about an hour my Jokerz suddenly let out a deafeningly loud feedback type of hum (It sounds like in back to the future when Marty cranked up the amp at Doc's house in front of the huge speaker before plugging in the guitar). I killed the power, cycled power a few times and then it went away. No issues after that, everything was fine. Yesterday i powered it on and it did it again, this time from initial power on. I could still hear the normal boot up "bongs" faintly in the background, and the game sounds are playing in the background as they should, but the deafeningly loud hum is back. This time it wont go away. I tried re-seating everything, checking grounds, etc, nothing made a difference. I don't wanna just throw parts at it. I checked the sound board caps with my multi meter (On the board, which i know isn't preferred or 100% accurate) and 90% of them were within tolerances, but a few were WAY off. But again, i realize that to test caps correctly i have to remove them. At that point I'll just replace them all since it's cheap and easy enough to do.
Anyone have any suggestions where to start looking? Will bad caps cause this insanely loud feedback? Rectifier?
And i want to stress again this IS NOT the normal Jokerz hum.