Hey guys. I just recapped my 212-75. All electrolytics were replaced. The only discrepancies were the two 400mf 25v caps. I replaced one with a 420mf and the other with a 440mf. Also replaced both driver transistors.
When I powered her back on, I got nothing but a loud hum. One power tube began quickly red plating. I'm not sure how to proceed. Any advice?
https://www.thetubestore.com/lib/thetubestore/schematics/MusicMan/Musicm...
Solved
One transistor collector was shorted to ground. All is working now. Except my phaser, which didn't work before the recap. Now to dive back in!
Take it to a tech
Hi there,
you need to take the amp to a qualified tech. If you took it upon yourself to replace parts without knowing enough about the circuit to troubleshoot it, I respectfully suggest to have somebody else look at it. We can't teach you electronics here, only advise on things particular to the MM amps. Why did you replace the transistors? Did they test bad?
Sincerely,
Lars Verholt
Your own reply arrived while I was typing
Glad you got it solved.
Cheers,
Lars Verholt
Hi Lars,
Hi Lars,
Thanks for your response and your concern. I should have been more clear about my experience with electronics. I have been working on this amp for many years, have built several amps from scratch and I know how to read schematics, etc. I like posting my problems on here so I can get some feedback and ideas from you all when I get stumped. I think I was premature posting this particular problem since I obviously figured it out pretty quickly. But like I said, thank you for giving me feedback and for providing this resource!