LG 60pb560v plasma tv no picture

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

i have found something strange,

when i only connect the bottom one i get the snowy picture look ok to me.

but when i only connect the top one i get a weird half snowy picture with a littlebit color in it. Made a picture of it verry weird

ill post a picture with it.

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

Now that there's a photo I say it is a Z-sus failure, take out your Z board and look for shorts, I'm sure something is defective there.
If you keep the TV on long enough these black splotches will clear and only the dancing pixels will remain.
Even though does some test pattern display on the TV or it shuts down so fast you can't determine?
Any other member that can provide insight is also helpful.
At the solder side of sustain board there are some 5 pin optocouplers(photo) that function as gate drivers for the transistors,if the transistors themselves are good then maybe these ICs failed.
How to test them: There can't be any shorts between red circled pins, and none between the yellow(approx 1V forward voltage and if reversed Open).
If you find the board for cheap then maybe replace it,but first gotta make sure that is the problem.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

Hi,

I'm going to measure that straight away. Thank you for your good explanation of how to do it.
I can't determine a test picture because it goes off very fast just a sec or so and then goes black.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

measured some things there are a few ic that go to zero, i dont know if this is normal. so i made pictures of them.

also the transistors i have a question about. the ones that have a red circle around them. one is measuring both ways a value of 500 and the other measures one way but not the other way.

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

If these 421 and 505 are volts,like 0.505V it is good,if is OHMs then they are bad.
It is hard for me to determine without having TV at hands, could you record a video of the screen when you power on the TV with both buffer boards?
What happens if you disconnect the panel connectors to Z-SUS?
Z-SUS has a +16V test point close to Z-bias, is it good?

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

hello hope everyone had a good christmas :-).

that are indeed OHMS so that means they are bad. but in the first two pictures if those read 0 is that bad too? the first two pictures are of the same component.

i m going to do the rest what you have said but it can take a moment for me to reply.

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

You have to not only look if it's 0 OHM, but also if the pins are connected to the same PCB trace, in the second picture that component has not the same pinout as the optocoupler, and they seem to be connected to the same plane, 0 OHM is ok there, but if you have a short at that optocoupler that is bad.
The "disconnect z-sus from panel" is model specific if that will work or not, LGs usually don't start in that condition
And now to begin desoldering those IGBTs that measure low OHMs and replacing them, sometimes they are in parallel and is harder to know which one is problematic, the first one from the third picture is bad, if the opto is also bad you will need a scrap Z or Y board from another same gen LG to fully fix this one, working Z-sus boards are cheap.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

hi all,

didnt got any further with the tv.

didnt ordered other boards.
the pictures i made where from the ysus board.
so i have to measure the zsus board.

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

Hi, did you come around to measuring both y and z boards? The picture seemed like a z-sustain issue, so i tought your findings were about that board, if it's Y then you have to decide wether to desolder and replace the IGBTs or buy a replacement board, I would desolder them anyway and measure their resistance off the board make sure they are the fault.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

hello again sorry for the late reply.

i m going to start over again because it is confusing right now . I have made pictures firstly of the z-sus board. can you help me to determine if it is good or bad?
how to measure and what to measure.

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

You have to measure resistance between all pins of the IGBTs, MOSFETs and diodes,these are screwed at heatsinks and on solder side SMD ones. Anything under 9k OHMs is worth noting.
Do this with Y and Z boards.

[thuss]

Re: LG 60pb560v plasma tv no picture

You'll be taking out the Y-SUS and measuring between the pins of these circles on the images.
YSUS
Top side - if the resistors are open that's a sign that something else failed.
Bottom side - I circled IGBTs,MOSFETs and their driver ICs,if you find a short on any of them that's one problem.
ZSUS board i coudn't find any decent pics of bottom,so i circled what you should measure on the solder side of the board, under these heatsinks are the pins of the transistor and diodes.

Hi Biruslapio

Just need some advice - On ic403, ic442,ic443. The outer two legs are (on the three leg side)are beeping continuously??. But on Ic400 top left leg reads/beeps continously with leg opposite side of ic. I was going to change them over but I am not totally completely convinced they are faulty, have you got any suggestions? Thanks (I dont know what the part numbers are)