Lg 50pq30

[mmoore5553]

I got this one for free and trying to figure out how to solve the no video. I turn it on and the light goes to blue and then flashes blue and then turns red. I hear the relay kick on and then clicks again.

I am not sure where to start checking. I can make a small video if you would like . Here is the pictures and going to include manual.

Oh there is no video at all. Which i am sure you know.

[mmoore5553]

Re: Lg 50pq30

Here is the manual. I have never worked on a plasma tv at all. I have a volt meter but I do not an oscilloscope.

[rccrasher65]

Re: Lg 50pq30

Start by checking all your voltages on power supply, with your MM set on DC volts.

[mmoore5553]

Re: Lg 50pq30

I have taken some voltages on the power supply. If I unplug point 1 and take voltages I have the following voltages.

VS = 193 V
VA = 59.5 V
M5V = 0 V
FUSE 801 =320

If i plug in point 1 then fuse 801 goes to 123 volts. I assume that is standbye . Also with point 1 unplugged the light stays blue on front. So i assume only with a load I have issues ? I seen in the manual I should make two 100 watt light bulb in series and go to pin 1 and pin 4 . But I am not sure if that is right or how to do it.

I hope that helps. Not sure where to go next.

[mmoore5553]

Re: Lg 50pq30

Here is a pic of what the board says the voltages should be.

[mmoore5553]

Re: Lg 50pq30

update - I was checking some of the diodes and components and noticed d304 was showing shorted. It did a continuity beep when i held it on. Usually I see diodes show 589 in circuit. I test others in circuit and they showed 384. Not sure if that is normal for this board or not.

[Clydeuk]

Re: Lg 50pq30

You would need to isolate one side of the diode to check it out of circuit, but no diode should read in both directions.

[mmoore5553]

Re: Lg 50pq30

Diode appears to be fine as others in right by it are reading the same. I could not get it out of circuit totally to read. Any other ideas ? Anyone know if i should test it with the ysus unplugged ? Or should i test it with it plugged in ? What is m5v ?

[mmoore5553]

Re: Lg 50pq30

I have gotten some more voltages which i thought was odd. At the connector going from the power supply board to the main board I have some of the voltages. That connector is p813. I have the voltages not in the red square.

Then i have voltages if i unplug the connector p811. P811 is going from power supply board to the ysus board. I then and only then get the rest of the voltages in the red square. If i leave the ysus plugged up I do not get those voltages in the red square.

Please let me know how else i can help and if i need better pictures. I find it odd i have no voltages until i unpug the ysus board.

Not sure what else i can give to help. I am not sure which board is bad and which one to replace. I did try to unplug the zsus board and those voltages did not show up in the red. So i do not know which board to replace or how to test ysus board and zsus board . Who knows i might be on the wrong track and please correct me if i am wrong. I always love learning . I am at a loss. I will wait to hear from smarter people.

I have included a pic to help show what i am getting. The voltages are almost on the dot too.

[rccrasher65]

Re: Lg 50pq30

It probably your upper y buffer that is bad. I had an LG50PG20 doing the exact same thing, and it was the upper buffer board. LG's have a lot of issues with the buffer boards going bad. carefully remove your upper buffer board, turn on set and see if you get half a screen. I'm no authority by any means, but with the help of a few guys on here I fixed a few plasma's My LG I tore the ribbon cable going to the Panel, so be careful. If you damage it, its scrap!

[mmoore5553]

Re: Lg 50pq30

Thanks Rccrasher. I will wait to see if i get some more people chime in on what i need to do or what to test next.

[rccrasher65]

Re: Lg 50pq30

If you disconnected the cable going to y- sus and you got your voltages back, then your y sus is probably the problem, or y buffer. Now you have to determine whether your y sus is good. If your VSC is to panel label voltage. then y-sus is good and buffer is problem. Go to Quick links and put in LG 50PG20 Plasma tv, and follow the instructions there.

[mmoore5553]

Re: Lg 50pq30

I am willing to buy new buffer boards and YSUS if that is the problem. I found some parts that are a good price at http://www.tvpartsguy.com/ I just need to know if I am on the right track or wrong. Or what steps I need to take next.

[mmoore5553]

Re: Lg 50pq30

Not much to update but i bought the new Ysus board and buffer boards. The parts are suppose to be here on Tues. I will update post then.

[mmoore5553]

Re: Lg 50pq30

I got the boards in and replace the Ysus board and buffer boards. I had sound come on and it was static. I was like well this is a good sign and then it went back out again. Now i am back to nothing. Not sure where to look. I am still missing the m5v. I can uplug the ysus board and get most of my voltages back except m5v. I am not sure if this is a bad part or not.

[rccrasher65]

Re: Lg 50pq30

Possibly, bad part. when you have P811 disconnected, do you have all your voltages, including the M5V. that voltage is very important. Tom66 is the expert, on plasma repair. Maybe you can ask him to chime in on your thread.

[mmoore5553]

Re: Lg 50pq30

I got a new mainboard in today and same issue. I am still missing the m5v. I am wondering if it was the power supply. I tried to invite tom66 but have not heard from him. UGH . The tv that will not turn on.