Display Problem LG50PG3000 - ZA. AEKYLMP

[chimina]

Hi,

Yesterday evening my LG plasma started having problems with a horizontal bar across the top of the screen not displaying the picture correctly (see attached pictures)

It mainly displays fuzzy red & yellow boxes.

I'm a newbie when it comes to tv's but i would have no problem replacing boards myself at home. I'm a unix sys admin & have replaced parts in many a server/pc/laptop

I haven't had a chance to open the tv yet as it's attached to the wall. At 40kg i'll need to drag a friend over to help take it down.

I was just looking for a starting point here. Any advice would be welcome.

Thanks,
Neill.

[tom66]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

This is common with this model - top Y-buffer board is bad.

It can be repaired, from memory there's a guy on eBay doing repairs for about £45. You post him your board and he repairs it and posts it back to you.

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Many thanks Tom.

I'll hopefully get it off the wall tomorrow & double check the part numbers etc. Either a replacement or repair by that guy would be ideal.

I'll let you know how I get on.

Thanks again.

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Hi,

I sent off the board for repair and finally received it back today after a couple of weeks.
I'm pretty sure i've connected it up properly but now the picture is pretty much gone altogether. (see pic attached)

Any ideas if this is a botched repair or a a loose connector?

Thanks again.

Neill

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Apologies the pic didn't upload. Attached now

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

That white vertical bar in the pic slowly moves across the screen from left to right

[tom66]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

There are two possibilities. One, the repair was done incorrectly, or two the Y-sustain is bad. Do you have a digital multimeter available to do a quick test?

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Unfortunately no i don't have one. I would have to buy one.

If the Y SUSTAIN was bad would i not have seen this issue originally? You can see in the original pics i attached that there was only a horizontal bar at the top gone. (apologies if i'm asking nonsense questions, i've no idea how those two boards interact)

If the repair was dodgy, i'll have to hope i can get my money back from ebay & just bite the bullet for a new board.

[tom66]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Just to make sure, did you make sure to connect the small connector that goes between the buffer boards, and the other connectors?

If the Y-sustain was bad, you would have seen this initially.

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Right i suppose first step is to take it apart and check all the connections are snug, i was pretty sure i had them all in ok (including the connector between the two buffer boards)

If that fails, i'll see if i can get ahold of a multimeter.

Thanks again Tom, i'll update the post tomorrow when i get a chance to look at the tv again

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Right so i checked all the connections and it seemed fine. Same result however.

Just to see i turned it on with the board completely removed and the attached pic is the result.

Does that mean its the Y-SUS??

Tvless for 3 weeks now and herself is starting to give me grief

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Oh and i managed to get a multimeter

[tom66]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Haha I know the feeling - but take a break from TV viewing and it is quite refreshing. I fix TV's but don't watch them much!

Since you have a meter can you supply two photos:
) one clear photo of the Y-sustain board
) one clear photo of the panel sticker - this has various voltages marked on it and the "LG Electronics" logo.

I recall diagnosing a similar model. With the upper buffer board removed the set had the same symptom.

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

It has it's upside, she's in her sisters alot lately "cause she has a tv" haha

I've attached the pics along with a pic of my (cheap) multimeter
I hope they're correct

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Were they the correct labels?

[tom66]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Sorry, missed your post.
You have a PDP50G1 panel.

See page 81 of this document:


You want to use the highest DC range on your meter, which is one click to the left from the "OFF" position.

Test Vsc and -Vy with and without both buffers connected.

You can ignore "white wash" mode as you can't access that menu.

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

Tom,

With both buffer boards in place the Vy read 195 and the VSC 135

When i removed the top buffer it read Vy 195 and VSC 137
When i removed both buffers it also read Vy 195 and VSC 137

[chimina]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

I forgot to test with just the lower buffer removed, do you need the readings from that too?

[tom66]

Re: Display Problem LG50PG3000 - ZA. AEKYLMP

No, these readings confirm your Y-sus is ok, it is the buffer that is bad.