Trying to fix this 58" tv for a friend. The red LED blinks three times then goes out for a few seconds, then repeats. Checked the backlight LED's and 3 were blown, so I replaced all 5 10-LED strips. Same thing, blinking red LED. Then I replaced the power supply board, no change. Finally I replaced the mother board, no change. Could the T-con board be causing this? Does the T-con talk back to the mother? Any help would be greatly appreciated.
The vast majority of this model I see need LEDs followed by bad mains. I never repaired/replaced a power supply or tcon. The tcon doesn't talk to the main AFAIK (most don't, very few exceptions).
You can try removing the LVDS cable on the tcon. If it starts and turns on the back lights, plug it back in and remove the ribbons to the display to see if the display or the tcon is loading it down.
You said you found some bad LEDS, did you note the voltage of them? They're either 3V or 6V. There are like 50 in this model, so you should be getting about 150V between pins 2N and 2P on the power supply when you start the TV, or about twice that if this model uses 6V LEDs. If there's a problem with the LED array, it will appear briefly and disappear, so have your meter on those points before you start it.
There's an excellent chance the main you bought is bad. There's a tact switch near the RF input on this board. Push and HOLD it in for at least 15 full seconds, release and push the power button to see if it will start and try that on your original board as well.
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