LG 50PZ550-UA Plasma has no picture or sound

[sredlin]

I need help trying to diagnose which board might be bad on my LG Plasma 50PZ550-UA TV. I can turn it on and see a faint glow on the screen, but no picture or sound, and the only button that works is the on-off switch, I can press the other buttons like menu and volume control and the red LED on the front panel will blink to indicate that the button was pressed, but nothing happens on the screen. I've already removed the back and checked all power supply board output voltages and they are all there on the correct pins on all output connectors, so I'm confident that the problem is not the power supply.

I've visually inspected all other circuit boards in an attempt to locate any obvious problems like blown out or puffed up caps, ICs or transistors with holes or burn marks, etc, and I did not find anything that's obviously bad. I now need to try to figure out which board/s might be causing my problem, and I'm not quite sure how to proceed with doing this, so any help here would be greatly appreciated, thanks.

Scott

[Hamie]

Re: LG 50PZ550-UA Plasma has no picture or sound

Run test patterns on the control board. loads of threads showing how to do this.

if you get test patterns you have a bad mainboard.

[ReeceyBurger123]

Re: LG 50PZ550-UA Plasma has no picture or sound

run test patterns on the control board. Loads of threads showing how to do this.

If you get test patterns you have a bad mainboard.

+1

[sredlin]

Re: LG 50PZ550-UA Plasma has no picture or sound

Run test patterns on the control board. loads of threads showing how to do this.

if you get test patterns you have a bad mainboard.

Thanks so much for the tip, I did see some threads about doing this, unfortunately I do not know how to do this? Most threads I found that talk about this describe a location to place a jumper wire to bring up the test patterns, and I am not sure where or even if my TV has such a location to place a jumper? I've carefully looked over all the boards several times trying to find a test pattern jumper, but I just don't know where it could be?

I have tried disconnecting the Y-Sus and the Z-Sus boards to see if anything changes. And disconnecting the Y-Sus causes the faint screen glow to go away, but still no sound, and disconnecting the Z-Sus, results in some very faintly visible snow on the screen, and again no sound. And all my power supply voltages are present on the correct output pins, so I feel like it's probably the main board, but I'm not completely sure?

[ReeceyBurger123]

Re: LG 50PZ550-UA Plasma has no picture or sound

I dont know how you cant find the threads google also provides loads of info, also yes your mainboard is bad very common on these.

[sredlin]

Re: LG 50PZ550-UA Plasma has no picture or sound

I dont know how you cant find the threads google also provides loads of info, also yes your mainboard is bad very common on these.

I did find a few different threads about test patterns and placing a jumper wire to view them, but I didn't find any that were specific to my TV model to provide the information I need to try to display test patterns. And there's no obvious jumper location on the circuit boards I have on my TV that's all.

I guess I'll try and find a main board to swap into it and hopefully it fixes it?

[ReeceyBurger123]

Re: LG 50PZ550-UA Plasma has no picture or sound

Give it a blast and keep us updated

[Hamie]

Re: LG 50PZ550-UA Plasma has no picture or sound

So maybe a better idea would be to upload a picture of your control board before buying parts you might not need?

Just a though!

[sredlin]

Re: LG 50PZ550-UA Plasma has no picture or sound

So maybe a better idea would be to upload a picture of your control board before buying parts you might not need?

Just a though!

Okay, the first picture is the logic control board, followed by the main board, and then the whole set of boards.

[dick_barton]

Re: LG 50PZ550-UA Plasma has no picture or sound

Short the two holes next to R51 & R52 with a paper clip or piece of wire. Unclip and remove ribbon cable A:325, power up and check if you have patterns on the screen.

[Hamie]

Re: LG 50PZ550-UA Plasma has no picture or sound

+1

[ReeceyBurger123]

Re: LG 50PZ550-UA Plasma has no picture or sound

Tbh I think the search feature here is a little fucked one day it brings loads of results the next it doesnt. Also follow what DB says the Lvds must be disconnected when you do this or the screen will remain primed but blank.

[sredlin]

Re: LG 50PZ550-UA Plasma has no picture or sound

Thanks all for your assistance with this, I will give it a try tonight or tomorrow, I'm at work at the moment so I can't try it right now, but I'll let you know what happens. Thanks again for your help.

Scott

[sredlin]

Re: LG 50PZ550-UA Plasma has no picture or sound

Short the two holes next to R51 & R52 with a paper clip or piece of wire. Unclip and remove ribbon cable A:325, power up and check if you have patterns on the screen.

I finally got around to doing this test, and it works, I have the test patterns on the screen, solid red, solid green, solid blue, then gray, followed by a series of sweeps across vertically and horizontally. So I'm going to try to find a main board to order for it.

I found one on ebay that has a slightly different part number, and have asked the seller if he knows if the part number he has for a 60" plasma, EBT61533403 is compatible with the board I have, part number EBT61533103, maybe you or someone else on this thread would know? Both the ebay board and my board have an additional part number that matches completely, the number is: EBR73043303. So I'm thinking that maybe they are compatible, but I just don't know for sure, the look the same in the pictures?

Here's the ebay listing if anyone wants to see it:

http://www.ebay.com/itm/-/232254340715?

[Hamie]

Re: LG 50PZ550-UA Plasma has no picture or sound

Try reflowing the BGA under the heatsink.
If that fixes the fault you could consider taking the board to a TV/console/pc repair shop and ask them to reball it.

Should work out cheaper than the replacment part.

However if you give it a good reflow it can last for a decent amount of time anyway.

£80+ for a replacement second hand plasma part is criminal.

[sredlin]

Re: LG 50PZ550-UA Plasma has no picture or sound

Try reflowing the BGA under the heatsink.
If that fixes the fault you could consider taking the board to a TV/console/pc repair shop and ask them to reball it.

Should work out cheaper than the replacment part.

However if you give it a good reflow it can last for a decent amount of time anyway.

£80+ for a replacement second hand plasma part is criminal.

I will remove the board and have a look, but I'm not sure I have the solder skills for doing a re-flow on something like that? Although there may be something to that, since I can't see anything obviously fried on the board as it's mounted. And I did run across several internet postings on youtube and other places about putting main boards in the oven to make them start working, but I'm a little leary about trying that?

And I agree the cost for "a replacement second hand board is criminal", but there just doesn't seem to be any other options for this particular TV. I guess this TV is just too old for LG to continue to make and sell parts for it now?

Thanks for the advice, I'll let you know if I try it.

Scott

[sredlin]

Re: LG 50PZ550-UA Plasma has no picture or sound

I fixed it, probably by, "reflowing the BGA under the heatsink...", as suggested by Hamie. The process I used to accomplish this, is shown in the following youtube video, with about 2 minutes of heat gun on each side of the board. I was pretty surprised that it worked, but it did amazingly enough. Thank you all for the help with troubleshooting, I'm really happy that I don't have to spend money to fix this right now.

https://www.youtube.com/watch?v=8sslythR5HE

[sredlin]

Re: LG 50PZ550-UA Plasma has no picture or sound

Forgot to attach the proof of concept photo.

[tmxmnz]

Re: LG 50PZ550-UA Plasma has no picture or sound

Thanks to you guys, now I know that my 50PZ950S as a faulty mainboard as the test partern is perfect.
Does anyone know how much heat (in Celsius please) and how much time it should be placed in hoven for a good reflow ?
In Swizterland LG ask me 240 Chf for this board - I may order it from the UK !
And don't forget: never buy LG shit again !

[tmxmnz]

Re: LG 50PZ550-UA Plasma has no picture or sound

Reflow (10 minutes, 200° C) does the job perfectly. How much time it will last ? Hope long enough so I can spare to buy a new TV ! I thank you so much for this guys, you're great.