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Hello. i need help with repairing ampeg svt classic. it turns on but like preamp is not working. Standby led is always red.
when i plug guitar in power amp in i get the sound.
when i plug guitar in power amp in i get the sound.
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Check C26 & 27 have 15volts across them. That is the main preamp power.
Don't forget to check and chang those six diodes; D29, 30 31, 39, 40 & 41.Support for Fender, Laney, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk
If you can't fix it, I probably can. -
hello jon. thanks for the advice. ive check the voltages across 26 and 27 they are 15.3 each. and diodes are looking fine? ;(Originally posted by Jon Snell View PostComment
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Hello Zeleni,
Since it seems you're not certain the preamp is functioning, you can of course always take the signal out from the preamp out jack to an external amp to prove that out. Then, you can move forward to the other issues which sound like they are audio power stage related. (;- )
Also, those stacked jacks, Preamp out & power amp in) have been known to be intermittent. You can of course just jump them with a 1/4" link cable.
That wouldn't of course create the amp being in protection issue.
GlenComment
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hello mars. ive tried that alredyOriginally posted by Mars Amp Repair View Post
power amp in gives me tone - power section is working
preamp out to power amp in - no tone
preamp put to other amp - no tone.
stand by led is still red.
the capacitors and diodes i was advised to check are ok! have any other clues?
thanks in advanceComment
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Ok i was able to fix it. a large 5w 47k r55 was broken. it looked like brand new from the outside but it was bad. replaced it and now everything is ok.
Thanks for help !!!Comment
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