Rotoflex4
Active Member
I've been recapping my AU-719 in stages, and everything had been going well. I did the boards one at a time and tested the amp after each stage. All good.....sounded great. Lastly, I replaced the filter caps and recapped the F-3101 board (Power Supply and Protector Circuit Board). It's the one wedged between the big filter caps and the transformers. So....I test it and the amp sounds wonderful......except.....when I flip the tone switch "on" the amp belts out a horrendous loud hum that completely obliterates the music. I haven't touched the Tone Control Board at any point. A lot of wires had to be detached and soldered to complete this stage, but I'm pretty meticulous about notes/photos and am pretty sure I have things connected OK. There was a tiny wisp of smoke from the middle of the F-3101 board for a few seconds after I turned the amp on. It was quite small though - I don't think I would have noticed it if I wasn't staring at it looking for potential problems. I thought that maybe a little dust or something was just burning off - maybe significant...maybe not....I don't know. I'm pretty methodical and careful but am a relative novice at this. It pains me to pull the F-3101 board again, especially if it isn't necessary. But with no obvious alternatives I may just have to do that. I've looked over the board with a flashlight and nothing appears fried. Anyone have any ideas where the problem might lie?
Thanks.
-Will
Thanks.
-Will