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Swr workingmans 300 power supply upgrade?

Discussion in 'Amps and Cabs [BG]' started by Dubious Aa, Aug 21, 2020.

  1. I love my old working mans 300 but it seems that the transformer may be on its way out... definitely gets warmer than it use to and i have had to repair the tracelines on the circuit board due to overheating.
    Has anyone attempted Replacing the transformer with a better PSU?
  2. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    Could be another issue causing the high heat.
    What issue caused the traces to burn up?

    And likewise is there excessive carbon tracking causing issues.
    If the original issue that caused trace failure wasn't resolved then I'm sure it's cooking.

    If it really is a bad transformer you'd have to know the rail voltage. Then use a transformer with correct voltage and current ( VA)

    If it has a tube pre it's a specialized transformer. If not would just have high voltage rails and big ceramic dropping resistors/ zeners for the 15 volt +/_ for the pre. SWR typically runs 2x 7.5 zeners in series.
    Have you measured opamp rail voltage. Or HV voltage? Any signs of strange voltage drop at idle? Excessive humming? Correct fuse rating?
    I'm just hoping someone didn't pop in a bigger fuse to " fix" the amp lol
    Last edited: Aug 21, 2020
    Wasnex likes this.
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