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  • #16
    I was on a hold to not do anything more until he decided. He did decide to do the filter caps, and I cut him a break to make it easy for him. I pulled the 47uF cap, and it is definitely bad.
    Apart from bad filtering, the scope pics looks like half-wave rectification. Do you get full B+ with the new 47µ cap? Repetition rate of ripple peaks should be 120Hz. If not check the rectifier diodes/connections.
    Last edited by Helmholtz; 02-23-2020, 03:35 PM.
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    • #17
      The 47uF was definitely the problem, it measured 6 nF out of circuit. The 22uFs measured good, but I replaced them while I was in there. Now B+ is back to normal, only a volt or two of ripple, and the scope looks normal. Amp sounds normal again. All power supply connections looked good on the board, but I hit the diodes just in case.

      Glad to be done with this!
      It's weird, because it WAS working fine.....

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