John Phillips-JCM 800?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by IIIBOOMERIII, Jan 22, 2008.


  1. IIIBOOMERIII

    IIIBOOMERIII Member

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    I have an 83 or 84 JCM800 2203. When I turn this amp on, it
    will buzz for about 2-4 minutes and then the buzz goes away.
    With the exception of the buzz when the amp is first turned on,
    it is a very quiet amp, even in melt your eye balls typical
    Marshall mode.

    This never really bothered me and it has gone on for a few years
    now. But, now that I am a little more hands on with my amps, I
    would like to track the problem down. Any suggestions as to how
    to start the trouble shooting? I am guessing that because of the
    age of the amp it could be a filter cap problem, as I have never
    had to have the amp serviced. The only thing I have had to do
    to this amp is changed tubes.

    Now I have changed 2 or 3 resistor values in the pre-amp
    section to get a tad bit more distortion. However, I had this
    problem with the amp before I did this mod.

    Thank you in advance John and anyone else who wishes to chime
    in.

    Eddie
     
  2. John Phillips

    John Phillips Member

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    I don't really have a good idea, except that it probably isn't the filter caps. It's more likely to be something like a resistor or joint with a crack in it that warms up and makes contact... or a ground screw connection.
     
  3. SatelliteAmps

    SatelliteAmps Member

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    Could even be a cold solder joint.
     
  4. IIIBOOMERIII

    IIIBOOMERIII Member

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    Thanks John and Satellite.
     
  5. donnyjaguar

    donnyjaguar Member

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    This is where cool-it spray comes in handy. You spray components with the cool mist until the fault returns and there's your culprit. This is shoddy troubleshooting in my opinion, but its what the old TV repairman used.
     
  6. IIIBOOMERIII

    IIIBOOMERIII Member

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    hahahaha what a great idea!!!! I am going to have to try that. Such a simple solution. Thanks Donny
     

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