Thanks to YouTube videos I've determined the following: Ready light is on. It flashes three times when you push power on button. The power board and the main board show no obvious damage. Fuses are OK on power board. I get 3.5V on each standby power tabs and 12V and 24V on other tabs on power board. The T Comm board looks fine. No LED lights show up from the back when TV is on in a dark room. Could not see any picture using the flashlight test no backlighting Does this imply the LED driver is bad? Is the LED driver integrated on power supply board on this model? The ribbon cable to the T Comm board comes from the main board not the power supply board. Or is it possible all LEDs are bad? Appreciate any advice for next steps
The led driver AND the T-con board are bad. If you could see a picture with the flashlight then the T-con board would be good. It is not. The led driver can be on the main board or the power supply board. You can get these parts from here: TV Parts Universal TV Stands DLP Chips ShopJimmy
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SOURCE: When testin a power supply or led board on tv do i test dc or ac with multimeter?
Your power supply board is working if you get audio and imgaes.
You test AC only the AC side of the transformer before the Rectifier Diodes. Everything after the Diodes will be in DC.
did you get to see any spec of backlight as shown in
LCD LED TV Repair No Image Blank Black Screen Flashlight Test How to Fix...
SOURCE: No back-light on LG LED TV
That means dead transformer supply chain. Replacing search not possible, donor Yes
SOURCE: LG 50la6970 no backlight i have sound and dark images!
Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis. http://electronicshelponline.blogspot.com/ To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.
The main power supply regulator section circuit fault. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Pull up older posts. http://electronicshelponline.blogspot.com/ It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.
Search the site by type in the "brand name" to your device; in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.
SOURCE: LG 47LN5750 No picture
If you have backlights its not going to be the tcon for future reference. you have some shorted or open LEDs in the panel. Check the voltage going to the LED sets, should be 100 plus volts
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