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Servicing Printed Circuit Board Amps


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After cleaning the innards of my most recent acquisition, I still receive an unpleasant buzzing noise (from the electronics, not the cabinet) about 98% of the time when I play. The other 2% of the time I receive no or very low volume from the speaker. I want to check out the soldering, but it's done on the opposite side of the circuit board than is visible. How do I remove the knobs and other parts of the amp in order to get ahold of the entire circuit board? Any tips will be appreciated.




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Depends on what kind of knobs they are. Either they'll just pull off of the plastic or split type shafts or they have set screws in the side. After that you need a socket driver to take off the nuts usually. Amps with PCB mounted controls and jacks are good candidates for solder touch-up. If it's a tube amp don't forget to safely discharge the filter capacitors! You need a big resistor for that job.


Don't get zapped! :eek:

Mac Bowne

G-Clef Acoustics Ltd.

Osaka, Japan

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what amp?

More than likely its a solder joint, or possibly a bad power transistor, don't know from the data you gave. Look and see if the top of your filter caps are puffed up a little, or the plastic around them are all crinkled up....signs of the cap shitting the bed. Could be lots of stuff, but once you've got the chassis out, check for loose components, its not uncommon. A visual check of the aforementioned, and beyond that....talk to a tech, or take it to a tech. Use caution, as previous posters noted.....plenty of juice left in caps, and of course work on it unplugged from the ac source. You might be surprised how many folks might not think of that! :)

I routinely solder every component in production solid state amps like Randall, Peavey, Marshall, Crate, and Fender....because of your complaint of your amp, and others.

Good Luck,


Down like a dollar comin up against a yen, doin pretty good for the shape I'm in
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