One channel perfectly working. Another channel I can hear sound very faint only if I tunr the volume really high. Do I have some kind of bad transistor or bad capacitor?
I am sure the pots are perfect.
Please help me if anybody has any idea.
I am sure the pots are perfect.
Please help me if anybody has any idea.
Cracked print somewhere ? might be favourite, or cracked track on a pot.
More info needed.
Are all inputs affected ?
A quick test is to (very carefully) buzz the inputs to the power amp if you have no test equipment.
More info needed.
Are all inputs affected ?
A quick test is to (very carefully) buzz the inputs to the power amp if you have no test equipment.
I have digital multimeter. I tried to buzz but no luck. I can hear very faint sound from one channel if I turn the volume very high. Only problem with one channel.
Does sound like a "fault" as such then on that channel.
Withhout knowing how experienced you are it's difficult to suggest anything.
If you have only a multimeter I would compare the DC output voltages of the amp with no signal. Should be zero. And then measure the quiescent current of each channel (volt drop over emmiter resistors) and compare good and bad channels. If that shows nothing then it sounds like an "AC" fault... a cap, broken print etc.
Withhout knowing how experienced you are it's difficult to suggest anything.
If you have only a multimeter I would compare the DC output voltages of the amp with no signal. Should be zero. And then measure the quiescent current of each channel (volt drop over emmiter resistors) and compare good and bad channels. If that shows nothing then it sounds like an "AC" fault... a cap, broken print etc.
Well it's nearly 2020 and I bought one of these amps in 1992 and it's still going strong.
I just posted to say that I had a similar problem and all I did was clean the front panel contacts (switches and pots) with electrical contact cleaner a few times and the problem went away. Some people say that this is the problem with amps doing this 99% of the time, which it was in my case.
I also adjusted the bias so that both were around 4mv (as stated in the manual) and checked the 4 power transistors attached to the heatsink (which were working fine).
So it is usually just dirt that causes lack of sound output/cracking (good news for most!).
I just posted to say that I had a similar problem and all I did was clean the front panel contacts (switches and pots) with electrical contact cleaner a few times and the problem went away. Some people say that this is the problem with amps doing this 99% of the time, which it was in my case.
I also adjusted the bias so that both were around 4mv (as stated in the manual) and checked the 4 power transistors attached to the heatsink (which were working fine).
So it is usually just dirt that causes lack of sound output/cracking (good news for most!).
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