I have a UN46H6201 with (at least) a dead backlight. It will power on and display a faintly visible setup image when illuminated by a flashlight, so I'm pretty sure the mainboard and tcon are fine. The question is if I need to replace the LEDs and or power board, or both just to be safe?
The board does not appear to be powering the LEDs. If I check the connector 6203 in the first photo, I find that there's only about half a volt between pins 11 and 10 (is that the right way to test? are these in series or parallel? I've been hesitant to poke around and test all pin combos because it's hard to get a probe in there). note the pin map is visible at the right of the photo.
The power board does have one component that looks singed, a diode (1st picture). Removing and testing, however, it shows the proper half volt voltage drop/infinite using my multimeter's diode tester.
On reddit somebody suggested I also test the bridge rectifier (2nd photo) in circuit with the TV on. The outer pins measure 135 volts, which the same person suggested was too low. The board is outputting the proper voltage for the mainboard at least, as I have tested with a multimeter and also empirically because the set will turn on. Nonetheless it would be trivially easy and cheap to replace the rectifier and diode, I'd just have to wait a week or so for mail order from digikey.
Finally, I also suspect I have some bad LEDs. This I tested by measuring the resistance on each of the LED backlight channels, after removing the plug from the power board. 3 showed infinite resistance, suggesting an open circuit, and one showed 50k or thereabouts. I haven't tried putting power to them, but obviously if the circuit is open nothing's going to happen if I put voltage to them. If there's a better way to test the LEDs I'm all ears.
So, what should I replace? Or is the set too far gone and I should just part out the tcon and mainboard and move on with my life? It's a nice smart TV, and my preferred size, 46", but you can get those for around $100 on our local used market so there is a cost/benefit analysis to be done. Still, I hate throwing good parts into the landfill.
The board does not appear to be powering the LEDs. If I check the connector 6203 in the first photo, I find that there's only about half a volt between pins 11 and 10 (is that the right way to test? are these in series or parallel? I've been hesitant to poke around and test all pin combos because it's hard to get a probe in there). note the pin map is visible at the right of the photo.
The power board does have one component that looks singed, a diode (1st picture). Removing and testing, however, it shows the proper half volt voltage drop/infinite using my multimeter's diode tester.
On reddit somebody suggested I also test the bridge rectifier (2nd photo) in circuit with the TV on. The outer pins measure 135 volts, which the same person suggested was too low. The board is outputting the proper voltage for the mainboard at least, as I have tested with a multimeter and also empirically because the set will turn on. Nonetheless it would be trivially easy and cheap to replace the rectifier and diode, I'd just have to wait a week or so for mail order from digikey.
Finally, I also suspect I have some bad LEDs. This I tested by measuring the resistance on each of the LED backlight channels, after removing the plug from the power board. 3 showed infinite resistance, suggesting an open circuit, and one showed 50k or thereabouts. I haven't tried putting power to them, but obviously if the circuit is open nothing's going to happen if I put voltage to them. If there's a better way to test the LEDs I'm all ears.
So, what should I replace? Or is the set too far gone and I should just part out the tcon and mainboard and move on with my life? It's a nice smart TV, and my preferred size, 46", but you can get those for around $100 on our local used market so there is a cost/benefit analysis to be done. Still, I hate throwing good parts into the landfill.
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