I'm trying to put a broken (and modded) V4B back to stock working condition.
First question: There are four 5W ceramic resistors that I'd like to replace but I can't figure out the value. I'm pretty sure they're the plate resistors, and they're marked "SB-1 5W" on the schematic. I haven't tested them yet, but they've probably drifted anyway.
Second question: is there any problem with over rating the voltage on the rectifier diodes?
Third question: When I flip the standby switch, I get a really loud rising howl from the speaker. The volume control is off. The filter caps seem to be working. I've tested them with a multimeter at least, and they do charge up the way an electrolytic should. I've replaced the bias resistors, the two caps in the bias section, and all the diodes on the board. Any suggestions where I should be looking next?
Thanks,
Neddyboy
First question: There are four 5W ceramic resistors that I'd like to replace but I can't figure out the value. I'm pretty sure they're the plate resistors, and they're marked "SB-1 5W" on the schematic. I haven't tested them yet, but they've probably drifted anyway.
Second question: is there any problem with over rating the voltage on the rectifier diodes?
Third question: When I flip the standby switch, I get a really loud rising howl from the speaker. The volume control is off. The filter caps seem to be working. I've tested them with a multimeter at least, and they do charge up the way an electrolytic should. I've replaced the bias resistors, the two caps in the bias section, and all the diodes on the board. Any suggestions where I should be looking next?
Thanks,
Neddyboy
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