I think T-CON board is bad, but I don't know where it is

>Let us know how you determined that the backlights are working.

With the back cover removed I can visually see that the backlights turn on (and off) (plus when the room is dark you can see a very dim blue glow from the backlight leaking through the blacked LCD panel). I have done the "flash light test" as well.

With the backlight known to work do you still need to know the backlight voltage?

Are there other points/voltages to test?

@Mark Krueger Sounds reasonable with the backlights. If you do get the backlight but you do not get a picture than the issue is most commonly related to the main board. In your case you already replaced that, then the issue will be the panel. Of course, check the ribbon cables from the main board to the panel. Make sure there is not corrosion or tears etc. on those. There are no schematics for the driver boards so we may be out of luck on that. There should be a few numbers on those boards. Could you let us know what they are? We might find some information on those.

The only other thing, and I am going out on a limb here, is that the power board does not supply all the voltages needed to the main board. Check the connector for the values and measure those. Let us know what you get.

Thank you for the info.

I don't see any obvious issues with the ribbon cables, and the ones with sockets I had previously disconnected and reconnected to make sure they were seated well. I checked the voltages you asked for on the power supply connector (that feeds the main board):

Top row: 0v, 12.87v, 12.87v, 12.87v, 12.87v, 0v

Bottom row: 0v, 0v, 2.98v, 3.33v, 0v, 0v

I also attempted to measure voltages on the ribbon cable from the main board to the panel drivers. I could have made mistakes because the lines are so small. But Pin 1 to Pin 95 seemed to be 0 v, while pin 96 was 3.33v. The labeling said there were 96 pins total.

Here are some of the numbers I could see on the driver boards:

02 tpts E88441

K6608TP/K0487EV ZZ

FLD: RUNTK0487FVZZ-A1-L6S-0C2V

FLD: RUNTK0486FVZZ-A1-L77-010W

K6607TP/ K0486FV

31 TPTS E88441

FLD: RUNTK0485FVZZ-A1-L73-00VW

K6606TP/K0485FV ZZ

JE695R3HD7K

08Q45609 C

BN96-51823A Q01 2033

@Mark Krueger what do the ends on the LCD look like? The ribbon cables where the driver boards determined? Noticed any corrosion etc? Let's see if there is any data on those boards available.

I may not have understood your question completely, but the first picture shows an example I believe, I think that ribbon cable shown is pasted/soldered onto the driver board and the other side I suspect wraps around to the actual LCD panel (I have not taken the bezel off or taken off the "layers" on the viewing side of the TV). Everything that I have inspected on the back side looks undamaged as far as ribbon cables, capacitors, etc. as far as my untrained eye can tell, I was unable to find a "smoking gun".