| Carver receiver HR-742 fixed,but has DC offset - Click HERE for Original Thread |
| steve p |
Hi. This receiver I`m working on was blown in one channel. I used original brand Toshiba C3182n and A1264n output transistors, and replaced all predriver transistors (with originals), and several open/burnt resistors. The receiver is working OK at this point,but it`s not 100% fixed. The "good" channel has 0 volts DC across the speaker jacks,but the channel I repaired has .039 volts across. I know the amplifier will not hold up the way it is,the outputs will blow again. Any ideas?
BTW,This unit apparently does not use differential amp transistors. I was going to pull them and check the gain (common cause of this problem),but they`re using an IC as a preamplifier stage. The IC does cross over in the ECG book,and I looked at the pinout and did some checking,but I could find no real discrepancy voltage-wise when comparing between channels on this chip,so I don`t know whether to suspect it or not. Since this chip contains most of the preamp stage,it almost HAS to be my problem. But I don`t know.
P.S. I know this is a long shot, but posted it in case anyone has seen this before. Thanks. Steve P. |
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| Frank Berry |
| I wouldn't think that an offset of .039 volts would be a problem for the amplifier. |
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