Amp Buzz and Hum. Need help!

CalderLund

CalderLund

Guest
Dec 18, 2015
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4,551
Toronto, Ontario
#1
I have a fairly old 100 watt bass combo amp that is buzzing AND humming like crazy. It buzzes with no bass is plugged in (no chord). Other amps running in the same power source sound fine. I do not have any lights on in the room nor any rooms in the house. Adjusting the volume and eq on the amp does nothing except with I turn the volume completely off. My buddy helped me lift the ground and the hum reduced but didn't go completely away and the buzz maintained the same volume. If anyone knows what is going on with my amp and how to fix it, that would be greatly appreciated. Searched other cases and couldn't really fix it.
 
#2
What combo and what country do you live in? If USA the mains are 60Hz, is it a 60Hz hum? Touch the tip of an instrument cable plugged into the input with the volume low and if it matches the hum that is line frequency (60 or 50Hz).
 
#4
Then chances are very good the old filter caps have dried up in the power supply. Not a difficult repair the question is do you want to put some money into it?

To anyone with an old piece of electronic equipment fire it up and let it run awhile at least once a year will help stay off this kind of repair.
 
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#5
B-string said:
Then chances are very good the old filter caps have dried up in the power supply. Not a difficult repair the question is do you want to put some money into it?

To anyone with an old piece of electronic equipment fire it up and let it run awhile at least once a year will help stay off this kind of repair.
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Exactly my first thought. Power supply filter capacitors need replacing.
It may clear up all of the other problems as well.
If it doesn't get them all, at least you have the biggest problem fixed.
And you can't fix any of the rest of it if while you have a bad power supply.
 
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#8
CalderLund said:
Would long and mcquade be able to fix this? And how much do you guys think it would cost? I don't know enough about electronics to do it myself.
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That really depends on the L&M. My local one currently has an alright tech but the old guy was horrible. Even then, I have a better guy for amps than L&M. I would ask some local cats if at all possible to get some reviews. Odds are the better techs work at the boutique shops than at L&M.
 
#9
Instead of spending money on it, I used the extenal speaker output with a cheap 15 inch speaker I had lying around. It has reduced the buzzing and high pitched frenquency to about an eighth of where it was before. I didn't expect this to do anything but now it seems that I have a usable rig. I don't know what this shows about what what's wrong with my amp and/or cab, is something else the problem. Oh and when I touched my finger to the patch cable, radio signals now come through.
 
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