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I have a Crate GX80 Amp that turns on and produces the usual hum, but there is no guitar sound when played into either of the inputs, and the channel select switch does not appear to do anything. It also makes a very loud crackling sound when touched in a certain way (difficult to reliably reproduce) or when turned on sometimes.
I opened it up and saw that there was some discoloration on part of the board near a wobbly resistor (its labelled "Colber 250 Ohm 5% CW10A)
(Im pretty sure its a resistor. One of the long blocky ones.) All of the other parts are firmly in place, but this one rattles around when touched. I want to know if I can fix this myself or if I should just sell the thing for parts.
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Another pic
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>>1164085
Really depends on your skill level. I'm okay at assembling electronics but poor at fixing these sorts of things unless obvious like burned out component.
I would check power supply first, then replace anything obviously blown. EBay is a good source. If I could get it running, would either sell or remove electronics and either run as raw speaker box with external amp, or right in an off the shelf amp circuit, using stock power supply. The PS case and speaker are most valuable parts... look on ebay you can find raw amp circuits from China cheap.
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Cracking and audio amps usually means bad or improper grounding. Yes the white things are power resistors, thats a 250ohm 10W resistor. You can probably unscrew the board and check the solder connections on the other side to see if heat has degraded the joints. Probably your best bet is to reflow all your through hole pieces, then start checking for failed components.
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>>1164208
This is an example of type of amp board I'm talking about https://www.ebay.com/itm/132060028549
Might need to build minor preamp circuit... might not.
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>channel select switch does not appear to do anything. It also makes a very loud crackling sound when touched in a certain way
If it sat unused for a while, the switch might be dirty.
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>>1164085
time to get out the multimeter
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>>1164295
Sillyscope massarace
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>>1164085
Had a Digital marshall give up on me there a while back, just started howling everytime it was turned on.
To be honest man the best thing to do is to have a look around online for ways to test guitar amps for faults.
But If you're not up many wasted hours or simply looking around at music shops for amp technicians then just throw it out and upgrade.
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>>1164085
>a wobbly resistor (its labelled "Colber 250 Ohm 5% CW10A)
>>1164085
>this one rattles around when touched.
The discoloration is from heating of the resistor.
The wobbly rattling is caused by the same heat (and cooling) fracturing the solder joint on the other side of the board.
A solid solder connection would hold the resistor in place against gently pressure.
It's a simple task to re-solder the resistor and try the amp again.
Thread posts: 10
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Thread images: 2