Need Help Repairing 60" Lg PN5700 Plasma tv

[navamous]

Hey all, I have a LG Plasma tv model pn5700 that has no video but audio works. This is the second time im repairing it. 1st time it had a bad y sustain board, ended up replacing the ysus and y buffer boards. Here is what ive measured so far

Vs 205V
Va 55v
VSC 147v
VZB 105v

Ive tried the auto ext gen test on the main logic board...still no picture. What to do next?

[Michale32086]

Re: Need Help Repairing 60" Lg PN5700 Plasma tv

It's been my experience that, with plasma TVs, if you have sound but no display, it's likely an X (Z) Sus board..

Do you get the same VS/VA voltages off the X-SUS board??

[navamous]

Re: Need Help Repairing 60" Lg PN5700 Plasma tv

Thanks for the feedback I will check the Va Vs voltage on the Z sustain board....

[Andrew F. Ali]

Re: Need Help Repairing 60" Lg PN5700 Plasma tv

You will not see a Va voltage on the Z-Main Bd. What I think he meant was Vs and Ve voltages. Look for any open fuses on the Z-Main Bd, since the Vs is good going to the Y-Main Bd and then to the Z-Main Bd. The Va voltage supplies voltage to the X-Bds along the bottom of the TV.

[navamous]

Re: Need Help Repairing 60" Lg PN5700 Plasma tv

It's been my experience that, with plasma TVs, if you have sound but no display, it's likely an X (Z) Sus board..

Do you get the same VS/VA voltages off the X-SUS board??

The VS (205)/VA (55) voltages check out to be typical on the X-sus board.

Let me check the Fuses....will get back to you guys...

[navamous]

Re: Need Help Repairing 60" Lg PN5700 Plasma tv

https://goo.gl/images/vjCLbu

This is the Z sustain board... where would i find the Ve?

[mmartell]

Re: Need Help Repairing 60" Lg PN5700 Plasma tv

Just behind connector P174 is the VZbias trim pot. Just above that is two pads marked with arrows. Put your probes on those two pads.

[navamous]

Re: Need Help Repairing 60" Lg PN5700 Plasma tv

Just behind connector P174 is the VZbias trim pot. Just above that is two pads marked with arrows. Put your probes on those two pads.

VZB is measuring 105V

[mmartell]

Re: Need Help Repairing 60" Lg PN5700 Plasma tv

Is -Vy on the ysus matching the sticker ?

[navamous]

Re: Need Help Repairing 60" Lg PN5700 Plasma tv

Is -Vy on the ysus matching the sticker ?

I don't see a location to test -Vy voltage. Please take a look at the image using link below:

http://www.tvpartsguy.com/lg-60pn570...1-ebr75455701/

[navamous]

Re: Need Help Repairing 60" Lg PN5700 Plasma tv

I manage to swap out the ZSUS board....but still no change. Now im leaning towards the YSUS board and buffers being bad.

This would be the 2nd time I would be replacing these boards.....what would cause the ysus to keep going bad?

[BigPete]

Re: Need Help Repairing 60" Lg PN5700 Plasma tv

Picked up a 60PN6500 recently with the same issue.
There was only 4V on the 15V line.

Y-SUS board number: EAX64789501
Z-SUS board number: EAX64789601

I replaced the following components on the Y-SUS to get it back up and running:

D509 - K8A60DA - Shorted
D603 - ES1C - Shorted
R251 - 2.2 Ohm resistor - Open

I also soldered some possible dry joints. I didn't put them under a magnifying glass to confirm it, but felt it needed doing.