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Tube guitar amp only has a hum. No other sound.Its not the tubes,not the 1/4" jacks,and not the speaker.For the hell of it I checked continuity on speaker wires,unplugged from speaker.There is continuity there with amp unplugged from the wall,is this normal?A 15k cement resistor also has continuity but still measures 15ohms.Is this normal? Talking about a 1988 fender champ 12,with pc board.Any input on what and how to troubleshoot would be very helpful.Thanks,Jim.

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  • perkinsj Apr 07, 2008

    hi, I thought it was the caps,but I didnt want to just start replacing parts without being sure.What about the 15ohm resistor?It has continuity when none of the others do.Thanks

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Hi,

you should only have one earth connected on your equipment to avoid a earth loop situation preferably the amp lift any other earths/ effects ect. to remove the hum loop if it is on its own and out of guarantee or a reasonable period say two years from the purchase date get a engineer to change the smoothing capacitors on the power supply look like to medium sized batteries on the power supply module as they are very prone to failure on trace elliot gear this should cure.

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Posted on Apr 07, 2008

  • Priya darshan Apr 07, 2008

    Was that comment for me?

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I would suggest to check the power supply section for defective capacitors.

Posted on Apr 07, 2008

  • Jaime Hernandez Apr 07, 2008

    Here is the schematic diagram.

  • Jaime Hernandez Apr 07, 2008

    If the value is 15 ohms, it will measure as continuity on the ohmmeter when using the continuity feature.

    Try to set the ohmmeter to ohms to measure the resistors.

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