LG 40UB800V-ZA won't power on, no video or audio

[KrisC]

Hi,

I have an issue with a 3 year old LG 40UB800V, it's an LED backlit to.

It started playing up about 2 weeks ago, would take a few minutes to turn on, then gradually over the course of the next week got upto about 10-15 minutes.

Yesterday however it failed to power on at all.

I had hoped that the caps on the PSU board were bad, they all looked good but I changed them all out anyway, still, it wouldn't power up.

I have a stand by light, when I try to power on the tv it flashes a couple of times then goes out, after about 30 seconds an LED on the PSU marked LD701 flashes 5 times every 5-6 seconds.

I have no video/no audio, I'm trying to power it up on its own with no external devises connected.

I fear it may be the main board that is dead but was hoping someone could maybe offer some assistance or impart some of there wisdom my way haha.

Many thanks.

[dick_barton]

Re: LG 40UB800V-ZA won't power on, no video or audio

Any photo's of the circuit boards. What voltages have you taken on the power supply board?

[KrisC]

Re: LG 40UB800V-ZA won't power on, no video or audio

I've tested all 3.5v, 12v, 24v and 37.8v points on the PSU board and all seem to be as they should, photo of the boards coming up.

[KrisC]

Re: LG 40UB800V-ZA won't power on, no video or audio





https://ibb.co/mNfQ2d

Hopefully they work, should be 3 pictures in all.

[dick_barton]

Re: LG 40UB800V-ZA won't power on, no video or audio

There is one picture I can see showing the whole back of the set. It's best to attach them to your post. Others with an identical model can follow the whole thread.
Can you post the voltages on all the pins and their names shown in the box. It could be that the main board is not sending back any signals.