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Hello evryone.
I've had trouble with this amp for some years now. The problem with it is that after a few minutes of normal operation, it stops amplifyng the signal and all you hear is this loud 50hz hum. If you hit the amp hard the signal comes back but it will shut after a few seconds.
The amp is not mine, it belongs to one of my bandmates. It's been taken to several repairmen thru the years. One said the speaker was shorted. He fixed this but a couple of months later the problems were back there. Another found a different culprit, but a few months of good tone was all he got.
I did myself something that actually did the trick. The amp, as I read on different places on the net, is very poorly designed and suffers from this behavior almost always- even the newer DSP version does. What I did was install some hefty heatsinks for the output transistors and drivers. Again, it worked for two months and died again.
I was thinking, all those years of malfunction may have damaged the output stage, as what you hear in the amp must be a safety device from the transistors shutting down the signal. Would some replacements do any good? What do you think? Also I don't think those mjw21192 are an easy find, what can I use as a replacement? Please don't tell me to go to Radio Shack or something like that, I live in South America. Sorry for the bad English and thanx in advance!!
I've had trouble with this amp for some years now. The problem with it is that after a few minutes of normal operation, it stops amplifyng the signal and all you hear is this loud 50hz hum. If you hit the amp hard the signal comes back but it will shut after a few seconds.
The amp is not mine, it belongs to one of my bandmates. It's been taken to several repairmen thru the years. One said the speaker was shorted. He fixed this but a couple of months later the problems were back there. Another found a different culprit, but a few months of good tone was all he got.
I did myself something that actually did the trick. The amp, as I read on different places on the net, is very poorly designed and suffers from this behavior almost always- even the newer DSP version does. What I did was install some hefty heatsinks for the output transistors and drivers. Again, it worked for two months and died again.
I was thinking, all those years of malfunction may have damaged the output stage, as what you hear in the amp must be a safety device from the transistors shutting down the signal. Would some replacements do any good? What do you think? Also I don't think those mjw21192 are an easy find, what can I use as a replacement? Please don't tell me to go to Radio Shack or something like that, I live in South America. Sorry for the bad English and thanx in advance!!
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