There's some very smart folks on youtube, diving deep into how these boards work. In some basic ways they all work the same but of course there's just enough variance in some to make it complicated at times.
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I will. Is there any chance it could be the FA6B22N?? I was saying that there was 7 volts on the FB line, but am not sure if that is normal or possibly is keeping the IC from fully operating...Comment
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I posted a pdf in post 20. Your VCC supply is underestimated 10v, but it should be about 18-22vAttached FilesComment
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I wonder if CP810 is ok.Comment
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If you have not, check DP802 and 803 Diodes on underside of board by the big caps. Also double check all those resistors, make sure none are open or drifted.Comment
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Thank you all, I will check tomorrow.Comment
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They test good.Originally posted by nomoresonys View Post
Which resistors? I've checked all the through ones and think they're ok.Comment
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With power applied on the bench, CM814 and CM815 have 10VDC, equal to the VCC of ICM801S, but CM810 reads 0VDC. Not sure what role it exactly plays, but there should be something right? Sure would love a schematic! 😬Attached FilesComment
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I would switch it out. Sometimes it's just easier, specially if you don't have an accurate cap tester.Comment
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Seems like we covered most of the potential faults, if it's not a bad solder, resistor, cap, guess that leaves the pfc IC. Guess you can check it for a short. I believe there's only one ground, maybe check, with tv unplugged, neg probe on neg leg of filter cap/hot ground, positive probe on each pin of IC, make sure only one pin has continuity as in only one will show 0 ohms or beep in continuity/diode mode if meter has that feature, same as testing a fuse.Comment
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Well, if this is a frequent malfunction, check the other components that are in the Repair list...Attached FilesComment
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Well test QP802CS, should prolly test the same as QP801CS, the numbers on them are the same, yes?Comment
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It would be easy enough to change out all the parts listed at the bottom of that parts kit. Those 4 blue caps and the 2 transistors, one of which you already changed out.Comment
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Yes lotas, this is exactly what I did to start the repair. But I'm still having this issue. I will check again though...Originally posted by lotas View PostComment
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I'm at a loss....everything I've checked seems ok, but I'm having trouble following the circuit to understand exactly where the 10VDC (that should be 14-29) is sourced from. It appears to start tapped off that big transformer and through a diode, but how is the TXFMR producing V without any switching happening. Does anybody have a schematic close to BN44-00874F?? Can anybody confirm that this board should be fully on when on the bench (like other samsung power supply boards), or do I need to install it?Comment
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Did you replace CM810?Comment
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