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I have a Marshall G100RCD guitar amp which keeps blowing fuses. Inspection of the circuit board appears to show to points that are burnt

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  • elcocoiee Apr 10, 2009

    hi, i have the same problem, but i think i can find out the bad components. i will find them and tell you later..
    it will be very helpful some information about schematic so i can deduce were is the problem.

    thanks.

    koko

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You have a shorted output channel. You probably see burnt resistors and very heat stressed areas of the board. That is a sign of the outputs being shorted. Unless you have experience in repaired amplifiers you will not be able to repair this yourself. If you change the burnt resistors, they will most likely burn up again. The output transistors for one of the channels are also shorted. They must be replaced along with every other bad component. If you miss just one of the bad components you will most likely burn up all the good parts you just put in. Resistors must be checked to make sure they are within the rated tolerance, capacitors must be checked for being shorted or being dry, diodes must be checked for being open or shorted, output transistors and driver transistors must be checked for being open or shorted, and the list goes on. It is a very difficult job for anybody not experienced in repairing electronics.

Take it to a reapir center that will work on those type of amplifiers, not all repair centers will.

I am very sorry to give you such bad news, but it is the problem you are having.

If you need any additonal help feel free to ask, if you decide you are going to try and fix it yourself I can tell you what to look for and how to check them, but without the proper equipment you will not be able to do this.

If you found this information helpful a rating of "FixYa" would be appreciated. The "FixYa" ratings is not just for helping you fix your equipment yourself, it is also for helping you decide if you can even fix it yourself or not.

Thanks, and I hope you find a good repair center.

Dave

Posted on Jun 28, 2008

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