LG 60pz950u no display

[jgrise]

Hello everybody, this is my first post. Forums like this are in my opinion the best part about the internet. It is much appreciated that experts in this field take time away to offer there expertise. I have been a master automotive tech for 30 years. I am a member of many automotive forums and enjoy helping people very much. Because of my passion to fix things it has made me a very good tech but it is also a curse in some ways" I don't like to throw something away that has broken " which brings me to this plasma tv. The tv is about 4 years old and up the day the display went out it never faltered in any way. There were no storms or power surges. All my entertainment devices are connected to a top of the line Monster surge protector. I was fast forwarding a recorded show on my dvr when the display went out. No noise was noticed at the time it went out. The picture, volume bar or any other info display all went out at the same time. There is a faint blue glow to the entire picture with a thin black horizontal line about 4 inches from the top. the tv powers up normal, the array of blue lights come on as normal and it stays powered up. I am not sure about the audio because I go through a separate 7.1 surround system. The light on the bottom flickers any time a remote button is pressed telling me it does receive remote signals. All voltages on the power supply are correct 203, 55 and 5 volts. I see nothing that appears burnt or overheated. I have also removed the buffers from the y sustain one at a time, all this did was remove that part of the blue screen, still no display. I am very much a novice when it comes to TV's, any advice or direction will be very appreciated. Thanks again for a wonderful forum.

[Andrew F. Ali]

Re: LG 60pz950u no display

Va: 55Vdc, Vs: 255Vdc, M5V: 5Vdc are good to have. There are two other voltages to consider, if you have them being generated are -Vy: -198Vdc and Ve: / Z Bias: 95Vdc.
Your problem could be 'Control Board/ issue.

[jgrise]

Re: LG 60pz950u no display

Which board do I check the voltage on ?

[Andrew F. Ali]

Re: LG 60pz950u no display

I don't have a SM. However, the Va, Vs and M5V is generated from the PSU. The -Vy and Ve developed in the Z-Sus Bd (the board on the LEFT when looking at the back). This is assuming too that the other voltages like 19V, 12V and 3.4V (Typical) are generated from the PSU. I suspect the latter 3voltages are produced by the PSU though.

[jgrise]

Re: LG 60pz950u no display

thanks for your help. I will look at the zsus board this eve for the voltage check points.

[jgrise]

Re: LG 60pz950u no display

I don't see any test points for vy or ve voltage on z or y sustain boards. Any other ideas would be appreciated.

[jgrise]

Re: LG 60pz950u no display

I did notice that two of the fuses on the psb have 333 vdc on them. Is this normal ?

[jgrise]

Re: LG 60pz950u no display

My VZB is 110 and my VSC is 150. As per the information label all the voltages are dead that I have tested. All the boards show no signs of discoloration like pics of the same model from other posts. There is an unusual oily appearance to the lower part of the black heat sink on the zsus board, not sure if that is evidence of a problem. I have looked at the solder joints on both the z and y sus boards and noticed the circular cracking on several joints. Is it possible they could be the cause. I had mentioned I am not sure about sound output. Any suggestions how I can test for sound since I can't tell what input I am on or if the sound is still disabled through the audio menu [as I mentioned I had surround sound connected to the direct tv DVR] Any help is appreciated.

[jgrise]

Re: LG 60pz950u no display

Reading other posts jepree has a 50pz550 with no display, are tv internals are very similar. The main difference is I do have a glow on my screen, a flickering led on the control panel and a constant led on the main board. I have been checking voltage on the control board that Hamie has jepree checking above the arrow. My voltages are also in the 3 volt range, I also hear a faint humming from the z and y sustain boards.

[Hamie]

Re: LG 60pz950u no display

Picture of y-sustain and control board needed.

[jgrise]

Re: LG 60pz950u no display

Thanks for your help, if you need pics let me know. Do you think the oily stain on the heat sink is a clue ?

[Hamie]

Re: LG 60pz950u no display

connect the 2 holes circled in the attached with a bit of wire (paperclip etc)

disconnect the lvds cable also marked in picture.


power on the tv

[Hamie]

Re: LG 60pz950u no display

VY test point located here

[jgrise]

Re: LG 60pz950u no display

vy voltage is -180, I will perform the other test and report back.

[jgrise]

Re: LG 60pz950u no display

Goes through test, all screen color look good. horizontal and vertical test look good. Still noticed the thin black horizontal line about 3-4 inches from the top.

[Hamie]

Re: LG 60pz950u no display

you have a faulty main board.

re-seat the cable on the Y-sus buffers that corresponds with the black line.

[Hamie]

Re: LG 60pz950u no display

if you cant get rid of the black line by cleaning the connections i'm afraid its there to stay.

[jgrise]

Re: LG 60pz950u no display

Any way to repair the main board or is it trash. Where is the best place to buy one you can trust ?

[Hamie]

Re: LG 60pz950u no display

possibly can you upload a picture of the mainboard.

[jgrise]

Re: LG 60pz950u no display

First off, thank you very much for your help Hamie. This forum has been a great source of information, your knowledge on plasms is a huge asset to the forum. Just so I understand this, removing the ribbon disconnects the video source and jumping the connections starts a test which confirms the ysus and zsus are able to charge the panel proving no faults in any other board. I uploaded pics of front and back of main board. I did notice a few areas on the back of the board that look suspect. Are there common fault areas on these boards? If I am able to repair the TV I would like to add a cooling system to it. I can't believe LG produces plasma TV's without cooling fans.