VIZIO XVT3D650SV T-Con board Causes LEDs to turn off. HELP!

[jdlowvoltage]

Hey guys, so I was give a VIZIO XVT3D650SV 65" tv. The indicator light blinks for awhile upon initially plugging it in. After it finishes what i believe is its boot sequence I can push the power button and the indicator light turns from amber to white signalling that its on. However I get no picture no backlight. I can press the power button again and the indicator light wont change until unplugged. I pulled the tv apart and noticed that when the T-Con board is unplugged from the LED driver board (Appears to be a 10 pin wire connector) I get backlight on the entire TV. But as soon as this cable is plugged back in nothing. So I ordered a replacement T-Con board (used) swapped it and same exact issue. I'd rather get some advice on troubleshooting before swapping another board. I'm not sure where to go from here any help is appreciated.

[heavymachines]

Re: VIZIO XVT3D650SV T-Con board Causes LEDs to turn off. HELP!

Odd design. Never seen a t con control led boards before. You're getting backlight after you disconnect t'con from led driver board correct? I suspect possible short in panel itself as it seems to be common problem with 65" sets or bigger to be more specific side drivers being shorted. You can try this test,,, disconnect the flat ribbons to panel from tcon and turn on then connect each ribbon 1 at a time each side see if you get a partial picture. There is another risk if the panel is shorted it can damage the tcon voltage regulators. you have 4 flat ribbons going to panel so try none then one at a time for each side.

[CapLeaker]

Re: VIZIO XVT3D650SV T-Con board Causes LEDs to turn off. HELP!

The signal for the backlight's (BLon) is coming from the main board. There should be a few BLon pins on various connectors on the PSU. Check the DC voltage on them for starters.

[heavymachines]

Re: VIZIO XVT3D650SV T-Con board Causes LEDs to turn off. HELP!

The signal for the backlight's (BLon) is coming from the main board. There should be a few BLon pins on various connectors on the PSU. Check the DC voltage on them for starters.

That makes more sense. He did say however he got backlight to come on by disconnecting red plug from tcon to led drivers and it came on but since i never worked on anything bigger than 60 inches i can't say, just from reading about bad panels on 65'inchers and bigger. This is interesting anyhow.

[budm]

Re: VIZIO XVT3D650SV T-Con board Causes LEDs to turn off. HELP!

The connector on T-OCN with red wires is for backlights local dimmimg(for that faked 100K:1 Contrast ratio), so if the dimming control lines stay low there will be no backlights even if the BL-ON is present, you need BL-ON and Dimmimg control signals to get backlights. It is still possible the replacement T-CON is bad.
Since he can get the lights source to be on so if the T-CON and main board is good then he should see images on the screen.
OP did not say if he gets Voltage to run the T-CON board or not.

Picture provided by shopjimmy.
http://www.shopjimmy.com/auo-55-64t0...con-board.htm#

[jdlowvoltage]

Re: VIZIO XVT3D650SV T-Con board Causes LEDs to turn off. HELP!

Hey guys, Sorry for the delayed response as I left for work for a couple months. While trouble shooting I ended up frying the main board ( I think). Lesson learned be very careful when troubleshooting with power on! Thank everyone for the help though! I ended up just parting it out. Onto my next project which is converting a 52" Sharp LCD to LED. Wish me luck.