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Picked up a Peavey Renown 400 recently, plays and sound great BUT 5 seconds after you turn it off, there will be 2 low level hisses that last about 3 seconds and they are a couple of seconds apart. Capacitors discharge maybe ? Had a Renown a few years that didn't do this...anyway I replaced the old filter caps with fresh ones, in the low and high volt side and the 2 electrolytics in the power section. Amp isn't noisy while running. I've isolated the preamp and tried it...doesn't matter if volumes are down all the way or if anything is on the input or not...I would think its in the power amp section...anybody point me in a direction ?
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Hi:
My first reaction is this, is it really a problem? MANY amps have brief instabilities as they power down. it hurts nothing, won't stress anything, and as you state is at low level.
His is not likely caused by caps, it is more likely a semiconductor.
Verify it is in the power amp by plugging a guitar into the power amp in jack, and turning its volume to zero, does the noise still happen?
If the noise persists, it is in teh PA. So pull U2, nore which way it goes in. Now try it. Still? Now pull U4 and try. Still? We have already gone way beyond anything I would have done in my shop.Education is what you're left with after you have forgotten what you have learned. -
yeah....I don't really mind it, as long is there is no underlying issue causing it, I can live with it. I'll swamp U2 and 4 just to see, otherwise the amp performs greatComment
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Swamp? Swap? U2 and U4 are not the same, no swapping. U2 is the compressor IC, it is there to prevent the power amp from clipping, the amp will function without it. U4 is in the signal path and could contribute.
I still vote just button it up and enjoy the amp.Education is what you're left with after you have forgotten what you have learned.Comment
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Sorry, didn't mean swap them with each other....I have spare units...and this amp is the revision where U2 was deleted...so all it has is one side the 4558 U4Comment
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