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View Full Version : bad filter caps?

Baconator
04-09-2007, 09:13 PM
Well, here I am a month later and I still haven't figured out the problem with my Boogie that I mentioned in an earlier thread (http://thegearpage.net/board/showthread.php?t=217216). I've reacquainted myself with an old high school friend's dad that worked on amps for a living and is only semi-retired and he's looking it over. In the meantime, I posted about my woes in a boogie forum and had a few folks suggest that my problems could be related to old filter caps. Although I've heard that filter caps need swapping out after 20 or so years, I've never really heard why.

So . . . . what are the symptoms of crappy filter caps?
Blue Strat
04-09-2007, 09:22 PM
So . . . . what are the symptoms of crappy filter caps?

Hum, loss of power, low voltages, blowing fuses.

What are your amp's symptoms?
Baconator
04-10-2007, 06:18 AM
Hum, loss of power, low voltages, blowing fuses.

What are your amp's symptoms?

It's a raspiness in certain notes when played at louder volumes. I was a little doubtful that it was the filter caps, but then I don't know much.:BEER
John Phillips
04-10-2007, 06:36 AM
That sounds more like a speaker problem or a microphonic power tube, or possibly something loose inside.

Filter caps do need replacing eventually though, even if that isn't the cause here - the chemical electrolyte inside degrades with age and becomes less effective, a bit like a lead-acid battery does.
Baconator
04-10-2007, 07:38 AM
That sounds more like a speaker problem or a microphonic power tube, or possibly something loose inside.

Filter caps do need replacing eventually though, even if that isn't the cause here - the chemical electrolyte inside degrades with age and becomes less effective, a bit like a lead-acid battery does.

I've gone through the typical troubleshooting by swapping tubes, changing speakers and poking around inside in the amp and haven't figured out the problem yet, although it would appear to be a loose connection somewhere. This has been troubling me for a few months now, moreso since I don't have a backup. I guess it's just as well I don't have a gig right now, but I still miss it. My M-Audio Black Box has definitely lost its appeal after relying on it as my only source for guitar sounds - especially since the Mark IIC+ model on it really stinks.

I'll give the tech another week to play with it and if that doesn't do it I'm sending it off to Boogie where Mike Bendinelli, the guy whose initials grace the back of the amp, still works. If he can't figure it out I don't know who could.