Weird stuff.
I press power on this receiver, I hear the relay click, I can play music and get radio, everything apparently works but not really. The big heatsink stays cold to the touch, the small heatsinks to the two voltage regulators on the mainboard get super hot, and there are two overheated brown areas on the mainboard with an identical pattern (circled in red), centered on the components on each side of the big capacitors (removed in these pictures). Those last components, of course, also get burning hot.
So...I spent the week with my novice skill trying to locate the problem.
I removed all the transistors and checked them with an analog meter's ohm setting and they appear to be good.
All the diodes appear to be good.
The rectifiers, too.
Q815 on the power supply board shows a short between emitter and collector but I don't see how this could be cooking components so far downstream. People say this symptom usually means a short.
There are no bridged joints anywhere in this receiver, no leads/wires touching other metal on top, no solder splatter underneath or on top, no metal debris, etc.
Studying the circuit diagram, I can't possibly see what special connection those cooked parts on the pictured board areas share, something that may be the bad component here.
I'm hoping someone here has seen this sort of thing before and can give me a clue.
I press power on this receiver, I hear the relay click, I can play music and get radio, everything apparently works but not really. The big heatsink stays cold to the touch, the small heatsinks to the two voltage regulators on the mainboard get super hot, and there are two overheated brown areas on the mainboard with an identical pattern (circled in red), centered on the components on each side of the big capacitors (removed in these pictures). Those last components, of course, also get burning hot.
So...I spent the week with my novice skill trying to locate the problem.
I removed all the transistors and checked them with an analog meter's ohm setting and they appear to be good.
All the diodes appear to be good.
The rectifiers, too.
Q815 on the power supply board shows a short between emitter and collector but I don't see how this could be cooking components so far downstream. People say this symptom usually means a short.
There are no bridged joints anywhere in this receiver, no leads/wires touching other metal on top, no solder splatter underneath or on top, no metal debris, etc.
Studying the circuit diagram, I can't possibly see what special connection those cooked parts on the pictured board areas share, something that may be the bad component here.
I'm hoping someone here has seen this sort of thing before and can give me a clue.
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