LG 47LW650S - no picture, no sound, no backlight, power ok?

[timschuerewegen]

I had paused my media player and when I came back after 10-20 minutes the TV screen was black but the power LED was white, so the TV was still on. At first I thought it was a problem with my media player but soon I realised that it was the TV. I really want to (try to) repair it because they don't make new 3D TVs anymore.

Symptoms:
- no picture
- no sound
- no backlight
- can still be turned on/off, power LED works (red/white)

Product Code
47LW650S-ZC.AEUYLJG

Power Board
EAX62865401/8 EAY62169801

Mainboard
EBT61401005 LD12C EAX63686303(3) 101216

I checked the voltages on the 24-pin connector between the power board and the mainboard with the TV turned on:

3.5V  => 3.540V
12V  => 11.93V
24V  => 24.32V
PWR-ON => 3.438V
ERROR => 0V
PWM  => 3.203V
DRV-ON => 0.042V

Anything else I should check before I use my hot air rework station on the SoC?

[nomoresonys]

Re: LG 47LW650S - no picture, no sound, no backlight, power ok?

"DRV-ON => 0.042V" Looks like the mainbooard is not sending the proper voltage to turn the backlights on.

[nomoresonys]

Re: LG 47LW650S - no picture, no sound, no backlight, power ok?

Try a simple reset, unplug tv for 5 minutes, hold power button in on tv for 30 seconds, plug tv in and try it.

[timschuerewegen]

Re: LG 47LW650S - no picture, no sound, no backlight, power ok?

Try a simple reset, unplug tv for 5 minutes, hold power button in on tv for 30 seconds, plug tv in and try it.

That was the first thing I tried, but still no picture/sound/backlight. The fuses on the power board are good, the voltages are good and visually everything looks good. It probably needs a SoC reflow/reball but I want to be 95% sure I didn't miss anything else before I attempt a (temporary) repair with some hot air.

[nomoresonys]

Re: LG 47LW650S - no picture, no sound, no backlight, power ok?

Try giving the bga a good heating with a hairdryer, see if it works if only for a bit.

[timschuerewegen]

Re: LG 47LW650S - no picture, no sound, no backlight, power ok?

The TV works again

- added flux around the edges of the SoC and tried to get it under the chip (not sure if this was necessary or had any effect)
- used kapton tape to protect the nearby components from the heat/air
- used my Aoyue 850C hot air rework station with the 9mm round nozzle on heat setting 5 and airflow setting 5 for about 1-2 minutes

[nomoresonys]

Re: LG 47LW650S - no picture, no sound, no backlight, power ok?

Nice job, thanks for feedback.

[dick_barton]

Re: LG 47LW650S - no picture, no sound, no backlight, power ok?

Bare in mind that this is often just a temporary fix so may be worth your while looking for a cheap replacement in the meantime.

[nomoresonys]

Re: LG 47LW650S - no picture, no sound, no backlight, power ok?

Bare in mind that this is often just a temporary fix so may be worth your while looking for a cheap replacement in the meantime.

+10, might want to try a fan solution to try to keep the chip from overheating.