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No output from either channel in Fender Blackface amp

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  • No output from either channel in Fender Blackface amp

    I did a full electrolytic re-cap on a 1965 Pro Reverb. When I powered it up, I had very, very little sound from an iPod. I thought PI tube? Nope it makes noise when I put meter to grids. Moving back to V1 and V2, I had 450v on the plates, 9/10 volts on the cathodes, and we know that's not right. I had signal on the grids, but nothing on the plates, but they did also make noise when I put meter to plates, so I know from that point forward is working. Eventually I found the rightmost ground wire that the first cathodes from V1 and V2 share was broken under the board. So no signal getting past the first triode in either channel. I fixed this and all is well. Another 65 Pro Reverb lives on.

    Thought I would archive this for future reference.
    It's weird, because it WAS working fine.....

  • #2
    I was surprised by the title of this thread because I didn't know you were posting a story with a solution. I didn't think YOU would have failed to find the answer to something like this. Glad to see your troubleshooting intact Always glad for the guys that service those old amps and I hope it went about as fast as writing it and you made some $$$.
    "Take two placebos, works twice as well." Enzo

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "If you're not interested in opinions and the experience of others, why even start a thread?
    You can't just expect consent." Helmholtz

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    • #3
      Originally posted by Randall View Post
      I did a full electrolytic re-cap on a 1965 Pro Reverb. When I powered it up, I had very, very little sound from an iPod. I thought PI tube? Nope it makes noise when I put meter to grids. Moving back to V1 and V2, I had 450v on the plates, 9/10 volts on the cathodes, and we know that's not right. I had signal on the grids, but nothing on the plates, but they did also make noise when I put meter to plates, so I know from that point forward is working. Eventually I found the rightmost ground wire that the first cathodes from V1 and V2 share was broken under the board. So no signal getting past the first triode in either channel. I fixed this and all is well. Another 65 Pro Reverb lives on.

      Thought I would archive this for future reference.
      Good job Randall and thanks for posting in the way that you did showing steps to figuring out issue May it help some other tech.

      nosaj
      soldering stuff that's broken, breaking stuff that works, Yeah!

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