SL3 Power Supply Board - No power, Red LED D1 On - any suggestions

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donberry

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One of my beloved SL3 fell silent last night, upon closer examination I didn't see the red led thru the woofer grill on so I removed the back panel to check it out. Before I go digging around in there, I noticed a red led light, D1 in the schematic was on. I didn't think it should be, figured that meant a faulty board but to be sure I opened up the other working one and sure enough, that light was out, so some type of fault triggers the led light to come on.
Question I have is would it happen to be something in particular that triggers it or does any fault trigger it ?
I'm hoping someone says something like "oh, yes, that means R10 needs replaced and you're good to go" but I have a feeling it won't be that easy. At worse am hoping it's a diode or that what I think is the lone transistor but I can be an idiot at times so that's why I'm here asking the experts.
any info appreciated.

EDIT - Either I screwed up the other board or more likely the light D1 comes on when you disconnect the woofer. When I 1st checked, the board from the speaker that wasn't working was out of the speaker, saw D1 on. I opned up the other speaker and D1 was off on the good speaker. I went ahead and took it off so I could compare values of components and now D1 is on on both boards.
I'd guess the "fault" is the woofer or the wires to the panels aren't attached.

So guess I'll just compare boards and see if I can't track it down
 
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fwiw if anyone else is trying to t/s one of these- though D1 lights on the good board, it goes out after a few minutes so a fault doesn't light it, a fault keeps it on. Not sure if it's the only problem but it seems the triac1 is faulty so I need to replace it. I could be wrong but reading pin 1 & 3 gave me around 32v off top of my head where on the bad one it was reading 32v to pin 1 but between 1&3 was 0v.
 
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