LG 50" Plasma 50PS30-UB powers on, no picture, no sound

[douellette88]

Hello, hoping someone can chime in and assist with this one. Have a 50" plasma LG that turns on when you push power button. Light in front turns blue and you hear the click on the power supply. I also see a green led on the T-con board, so Im assuming that means both the T-con and the mainboard are fine? Tried unplugging the Y main and z-main, one at a time but no difference. I get no backlight, no menu's no sound nothing. Would you suspect the Y-main being bad? I also see no blown caps on any of the boards. Tested all fuses and none of them showed OL. Any help would be appreciated, thanks!

[Hamie]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Pictures needed of y and z sus.

You'll need to check voltages,

Vs & va located on power supply.
Vsc and -vy located on y-sus
Zbias located on z-sus

There may be test points etc or they may be measured across a resistor.

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

pictures attached, let me know if that helps any.

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Ive also attached the service manual for this tv as well

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

bump, anyone? I'd really like some help on this to get it fixed asap

[Andrew F. Ali]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Pictures needed of y and z sus.

You'll need to check voltages,

Vs & va located on power supply.
Vsc and -vy located on y-sus
Zbias located on z-sus

There may be test points etc or they may be measured across a resistor.

Did you check for these??

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Did you check for these??

Hamie asked for pictures of what I am working with, so I was waiting for a response from him to see what to do next. I would need some guidance on how to test these circuits without shocking myself.

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Bump, update.

Plugged tv in and tested voltage on both plugs that go from power supply to y sus and z sus. All voltages are normal on both. Also I get a green power light on the t-con board. Again no visibly blown or burnt parts.

Anyone else have input for the next step?

[tom66]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

As requested by Hamie, check -Vy, Vsc and Vzbias. These are marked on the Y-sustain and Z-sustain. The Y-sus has -Vy and Vsc, the Z-sus has Vzbias. Usually, there are components you have to test across.

If you're still unsure give me the "PDP model number", this is the model of the internal display panel assembly and will be something like PDP50K90000, marked on a sticker marked "LG Electronics Korea" or similar and I will get you a guide.

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

The only thing I was aware of was the 5v, Va, and Vs which all tested good. No idea how I would test what you mentioned. The model is pdp50h30022.

If you have ideas on what to do that'd be great!

[tom66]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

OK search for "50H3" in this document

[SM].pdf.pdf&mfg=LG-Zenith

It tells you the steps for testing.
DO NOT adjust anything yet... we need to see if there is an obvious fault, since this does not cover troubleshooting.
You can ignore the oscilloscope stuff too.

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

OK search for "50H3" in this document

[SM].pdf.pdf&mfg=LG-Zenith

It tells you the steps for testing.
DO NOT adjust anything yet... we need to see if there is an obvious fault, since this does not cover troubleshooting.
You can ignore the oscilloscope stuff too.

I think you sent bad link, says 404 not found

[tom66]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

try copying this into your browser URL

http://www.toms-service-manuals.com/getfile.php?mode=viewpdf&req=LG_Plasma_Panels_42G1_42G2_42T1_42V7_42X2_42X2A_42X3A_42X4A_50G1_50G2_50H2_50H3_50R1_50T1_50X2_50X3_50X4_60H1_60H2_60H3_60R1_60X6_60X7_71H2_panel_alignments_[SM].pdf.pdf&mfg=LG-Zenith

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Alright vsc and vy are right on. Vzb is 115 and sticker says it should be 105. Does that mean the z board is bad?

[tom66]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Thats OK for now.
Do you have a faint glow from the screen?

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Thats OK for now.
Do you have a faint glow from the screen?

No I don't seem to see anything on the screen at all.

Also the label say vy is supposed to be negative. I'm 99% sure my meter said +180 rather than -180. Is that okay?

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Hey tom is there a way to reach you faster than on this forum? I really appreciate your help

[Hamie]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Sorry for late reply. Your-vy is ok.
You positive that the panel isn't glowing. You may need to darken your room to confirm.

[Hamie]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

If you unplug the z-sus do you get an image?

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

No I do not on either of those questions