Hi
Yesterday, I changed the power supply capacitors and bypassed the input capacitors as specified by a service bulletin by shorting C1 and R4 and placing a 1K at the place of C2 After doing these jobs, I adjusted the bias and dc outputs. I let the amp all night long on the bench. It was working great. Today, I decided to try it in my system and when turning it on, I heard a buzz in the speakers and main fuse burned. I tried the amp with a variac on the bench and now both channels have high dc offset at over 15 volts on both channels. What happened. It worked great on the bench and broke when I tried it on the system. On the bench with high DC offset, the output transistors seems to have the same voltage across emitter resistors.
I suspect oscillation problems during trying it in the system that broke something. If the problem was caused by oscillation, what could be the faulty parts ?
Thanks
Yesterday, I changed the power supply capacitors and bypassed the input capacitors as specified by a service bulletin by shorting C1 and R4 and placing a 1K at the place of C2 After doing these jobs, I adjusted the bias and dc outputs. I let the amp all night long on the bench. It was working great. Today, I decided to try it in my system and when turning it on, I heard a buzz in the speakers and main fuse burned. I tried the amp with a variac on the bench and now both channels have high dc offset at over 15 volts on both channels. What happened. It worked great on the bench and broke when I tried it on the system. On the bench with high DC offset, the output transistors seems to have the same voltage across emitter resistors.
I suspect oscillation problems during trying it in the system that broke something. If the problem was caused by oscillation, what could be the faulty parts ?
Thanks
