An odd problem to watch out for. For amps that have sat unused for years.

Discussion in 'The Workbench' started by Matthews Guitars, Jan 28, 2020.

  1. Matthews Guitars

    Matthews Guitars Well-Known Member

    Aug 17, 2019
    Likes Received:
    I'm restoring my 1973 vintage Superlead. REALLY restoring it, all the way to having stripped it down to a bare chassis and had the chassis re-galvanized and yellow zinc chromated. All the hardware including the transformer bells and brackets have also been regalvanized or, if broken, replaced.

    Today was reassembly day. It's together and working. I had NO assembly errors but when I put it back together I wasn't getting anything out of it via the input jacks.

    When I got this amp it was so dirty that I scraped layers of dirt off it with a small chisel. I had to scrub the PC board clean. I'd almost think it had been stored in a barn for 20 or 30 years.

    It had a lot of dirt on both sides of the early ST1 board. So much that there was trace corrosion. I resoldered and cleaned all the traces as part of the disassembly.

    Well, it turned out that its failure to run after reassembly was due to a trace that connects to ground, that wasn't a complete trace anymore. It had corroded through. So, I bridged it and inspected the rest of the board to see if that might be necessary in other spots as well. I did find a couple that were looking questionable and bridged them as well, using short pieces of hookup wire and solder.

    The amp works just fine now. And sounds great, too!

    The lesson here is, when dealing with a very old Marshall, or any amp, and it's got a pile of dust and dirt on the PC board or evidence of trace corrosion, really focus on checking the trace condition. It might save you a lot of headaches and troubleshooting time.
    SkyMonkey, Sustainium and South Park like this.
  2. South Park

    South Park Well-Known Member

    Sep 14, 2019
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    A lot of people store amps in the garage a lot of dust turns to dirt. Need to keep things covered

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