lg60pz570 no picture - overheating??

[marty12345]

Hi all,

I have a lg plasma 60pz570 and recently picture went off (no backlight) but sound is still on while I was watching tv. I turned it off and back on and tv worked normally again for few minutes then goes black again.
First time tv works ok for 30minutes or so and then after it last only few minutes. I also noticed that when the temperature is cooler the tv lasts much longer sometimes 2 hours or so but when its warm then goes off much quicker.
This leads me to believe that its kind of an overheating issue??
I have tested some voltage points when the picture goes off and both Va and Vs are good to both y sus and z sus boards but Vy, Vsc, Vzb read low or no voltage. 5V rail is good but 18V rail on the input of the control board reads very low voltage.
I checked all the caps and visually checked all the boards both sides but cant find anything unusual.
Would like to atleast narrow it down to a board but not sure where to go next.
Any help would be much appreciated.
Model no. : PDP60R30110

[Hamie]

Re: lg60pz570 no picture - overheating??

Pictures?

[marty12345]

Re: lg60pz570 no picture - overheating??

Here are some pics
Thanks

[Hamie]

Re: lg60pz570 no picture - overheating??

Ok connect the 2 holes here beside resistors r51 and r52 with a piece of wire or paper clip etc.




Now disconnect the lvds cable (P31) here:




Plug in the tv.

You should now get test patterns, let them run for as long as the fault usually occurs.
If the fault doesn't happen then the main board is the problem.
If the fault does happen then it rules the main board out.

[Hamie]

Re: lg60pz570 no picture - overheating??

Also the way the this tv is wired it should run with the z-sustain disconnected.
The image will be of poor quality but you can rule the z-sustain out by running the tv with z unplugged. If the fault happens the z-sus can also be ruled out.

[marty12345]

Re: lg60pz570 no picture - overheating??

Ok will try both of them.
Will report back
Thanks for your reply

[marty12345]

Re: lg60pz570 no picture - overheating??

I tried the test pattern and after a while the fault occured so as you said it wont be the main board.
I have disconnected the z sus and the fault didnt occur. So by that u think its the z sus. Although i m not quite sure. Since i think its related to overheating issue the reason why the fault didnt occur because the picture was almost black when z sus was disconneted and the tv runs cooler when darker pucture??
Is there any other tests i could perform?

Thanks

[Hamie]

Re: lg60pz570 no picture - overheating??

Well if the fault isn't occuring with the z-sustain unplugged it gives us somewhere to start.
Since it seems to be heat related you could try heating up the z-sus with a hair dryer and see if the fault happens quicker.

Alternatively, pop it in a freezer bag and freeze it for while and see if it lasts longer.

Check the z-sus for dry cracked solder joints.
Pay particular attention to coils and anything mounted on a heatsink.