I have repaired this model about a dozen times with bad backlights causing Q9101C on BN44-00787A to short out. Usually I find about 50% of the LEDs shorted. I typically replace the FET, power up the TV to check the panel before ordering a new set of strips.
I picked up this model from a guy that had two TVs (one broken screen) and three power supply boards since he tried to repair himself. Two of the boards had a burned up Q9102C. The third had a shorted Q9101C which I repaired and put in the good screen TV. When I plugged it in, I heard some popping and quickly unplugged. When I checked the backlights, the majority were shorted and a few were blackened. I checked the backlights on the broken screen one and they were all good so I just swapped panels and got a working TV.
Testing the two blackened boards, only one of the two had a bad Q9102C which I replaced. The top rail is only outputting 215V vs 315V on the good board and printed silkscreen. Controller IC is likely SEM5027 or SEM5028. Checked all the FETs, power diodes and sense resistors and they seem ok. PFC voltage is good (390V) and Vs is stable at 12.7V.
Interesting side note that substitute boards from another model are being sold by Chinese sellers AND Shopjimmy on ebay for this TV. They have moved the AC connector to match the mounting and scrubbed the old part number off the board.
I picked up this model from a guy that had two TVs (one broken screen) and three power supply boards since he tried to repair himself. Two of the boards had a burned up Q9102C. The third had a shorted Q9101C which I repaired and put in the good screen TV. When I plugged it in, I heard some popping and quickly unplugged. When I checked the backlights, the majority were shorted and a few were blackened. I checked the backlights on the broken screen one and they were all good so I just swapped panels and got a working TV.
Testing the two blackened boards, only one of the two had a bad Q9102C which I replaced. The top rail is only outputting 215V vs 315V on the good board and printed silkscreen. Controller IC is likely SEM5027 or SEM5028. Checked all the FETs, power diodes and sense resistors and they seem ok. PFC voltage is good (390V) and Vs is stable at 12.7V.
Interesting side note that substitute boards from another model are being sold by Chinese sellers AND Shopjimmy on ebay for this TV. They have moved the AC connector to match the mounting and scrubbed the old part number off the board.
Attached Files