Hey,
I finally got the courage to open up my old Sherwood RV-6010R reciever. I know it has a few issues, but wanted a real challenge. The front speakers has gone completely silent. Checking signal continutity it seems fine until it reaches the main power transistors which doesn't seem to add any gain whatsoever.
So I started by checking voltages. My main concern is that there is a significant amount of AC on the B+ line, which supplies the big power transistors with power. Is this normal?
The DC voltages are as expected, but I also measure almost 70VAC on B+ when CNT602 is disconnected (about 104 when it's connected)
Is this normal?
capacitors C606 and C607 are missing, I guess to cut costs, should I put them in?
I tried also removing C614 and C613, and lifted the "output" legs on the positive half of the bridge rectifier.
On the negative half I get 35VAC in on each input and 0VAC out and -32VDC out, like I'd expect.
on the positive diodes I get 35VAC both before and after the diode (when only one leg in circuit) along with +16V at the output. If I turn the diode around, I get 0VAC, and the expected -16V.
but why does the diode let through AC in one direction and not the other direction? Is this normal? I thought diodes were meant to allow current in only one direction?
I finally got the courage to open up my old Sherwood RV-6010R reciever. I know it has a few issues, but wanted a real challenge. The front speakers has gone completely silent. Checking signal continutity it seems fine until it reaches the main power transistors which doesn't seem to add any gain whatsoever.
So I started by checking voltages. My main concern is that there is a significant amount of AC on the B+ line, which supplies the big power transistors with power. Is this normal?
The DC voltages are as expected, but I also measure almost 70VAC on B+ when CNT602 is disconnected (about 104 when it's connected)
Is this normal?
capacitors C606 and C607 are missing, I guess to cut costs, should I put them in?
I tried also removing C614 and C613, and lifted the "output" legs on the positive half of the bridge rectifier.
On the negative half I get 35VAC in on each input and 0VAC out and -32VDC out, like I'd expect.
on the positive diodes I get 35VAC both before and after the diode (when only one leg in circuit) along with +16V at the output. If I turn the diode around, I get 0VAC, and the expected -16V.
but why does the diode let through AC in one direction and not the other direction? Is this normal? I thought diodes were meant to allow current in only one direction?
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