Fender 68 Custom Twin Reverb

[bsco]

I have this unit here and when the reverb control was turned up, it caused feedback.....even with ALL other controls turned down...I found a 12AX7'A installed in place of a 12AT7....but that didn't make any difference....I pulled the tank to have a look and with the tank outside the cabinet the feedback was gone....so I re-installed the tank inside the pouch and just laid it there.....no feedback...then I secured the pouch in place and re-checked....no feedback....I checked here for previous posts and came up with re-locating the tank as a solution..but I put the tank back in the same spot as it was in the beginning....but I still don't know exactly why it was feeding back...I can now crank all the controls wide open with no problems......isn't electronics wonderful....

[52 Bill]

......isn't electronics wonderful....

I've had them oscillate like that when the return side cable has a bad ground or a loose RCA plug.

[bsco]

I checked for loose cables as I found that was a problem with the Blues Juniors...but these seemed to be a tight fit...but then again...well it works now....
Cheers,
Bernie