Gregory
Soundco Kid
A Yamaha CR-2040 Receiver is now on my bench after an AK'er purchased it recently, and he asked me to take a look. The power supply for the lamp circuits is reportedly dead and blowing fuses, though power has not been applied and no fuses have been sacrificed yet to verify this.
I've been able to trace the problem (theoretically) thanks to the excellent factory Service Manual. Apparently D912 is connected to the power transformer center tap (25 VAC) YE (yellow) wire and is filtered by C927, a 470uF, 35V electrolytic. From there it feeds 8 panel lamps, and the dial pointer lamp through parallel resistors.
A photo of the PCB with empty fuse holders.
Just so everything is perfectly clear, the schematic is marked-up below.
I'm 80 - 90 % sure the problem is a blown diode D912, P/N W03B, also 1S1885.. 1A, 100 PIV silicon rectifier, commonly known in the USA as 1N4002?
Wanted to run that by some of you experts here.
Original thread: http://audiokarma.org/forums/index....p-when-turned-off-only-not-on-turn-on.493168/
-Greg
I've been able to trace the problem (theoretically) thanks to the excellent factory Service Manual. Apparently D912 is connected to the power transformer center tap (25 VAC) YE (yellow) wire and is filtered by C927, a 470uF, 35V electrolytic. From there it feeds 8 panel lamps, and the dial pointer lamp through parallel resistors.
A photo of the PCB with empty fuse holders.
Just so everything is perfectly clear, the schematic is marked-up below.
I'm 80 - 90 % sure the problem is a blown diode D912, P/N W03B, also 1S1885.. 1A, 100 PIV silicon rectifier, commonly known in the USA as 1N4002?
Wanted to run that by some of you experts here.
Original thread: http://audiokarma.org/forums/index....p-when-turned-off-only-not-on-turn-on.493168/
-Greg
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