DP50747 Troubleshooting

[Twithers]

I picked up a Sanyo DP50747 in need of repair.

There is a roughly 2" strip across the top that is displaying properly. The rest of the screen is backlit, but no video.

Opened her up and on the LG control board, D1 & D2 are off and D3-D5 are off.

The previous posts seemed a little unclear on how to self test it, so I thought rather than being impatient, I'd see what kind of input you guys have.

Any suggestions to get me rolling in the right direction?

Thanks.

[tom66]

Re: DP50747 Troubleshooting

Plasma?
Can we see a picture of the fault on the screen?

[Twithers]

Re: DP50747 Troubleshooting

Looking through the previous posts, the definition of a fault screen is a bit cloudy.

Do you mean the actual display as it is shown on the screen when you turn it on? The actual Diagnostic board with D1 through D5 on it? Or the screen of the tv when it is in self-test mode?

I just don't want to give any extraneous information.

Thanks.

[tom66]

Re: DP50747 Troubleshooting

A picture of the TV connected to an ordinary source, displaying ordinary TV or a film, so I can judge how it looks generally.

[Twithers]

Re: DP50747 Troubleshooting

Ok, I'll get that for you.

It's going to be tough to see anything though. The screen is black except for the top inch or 2 across. When I turn it on, I can see regular lack of antenna static in that small horizontal strip at the top of the screen and the very top of what would be the blue square that shows channel numbers and stuff. With the rest of the screen being black, but still backlit. There is sound and the side controls work normally.

I opened it up again after reading the Plasma TV Troubleshooting post and following the "no picture" guide, because it's not out on the bottom "half" or top "half".

I checked the Y controller fuses and they are good. I swapped their position, just to see and there was no change. I checked the connections on the Y control board and they were all seated. And then I finally pulled the same board and inspected it for visual defects and cold solder joints, but found nothing. And the original fault was the same after reinstalling the board.

Not sure if it's normal, but the diagnostic led's all flash at varying speeds when it is turned on, meanwhile the screen is all black. After several seconds, the led's settle down to D1&D2 off and D3-D5 on and the screen comes on with the skinny top strip. The flashing led's and all black screen seems to happen when the set is first turned on after sitting unplugged for a while.

I'm trying to be as proactive as possible and not wait to be spoon-fed guidance, but I've yet to find a solution.

Thanks.

[tom66]

Re: DP50747 Troubleshooting

Oh, I thought it was all except that bar that was visible. Either way, the symptom indicates a bad buffer IC on the buffer board somewhere.

[Twithers]

Re: DP50747 Troubleshooting

Buffer board, huh? The guide doesn't mention that board, so I didn't even check it out. I'll have to find where that one is.

I don't have IC replacement capability. Any chance it would just need a solder reflow or do they fry internally and that's it?

Side question.... As far as plasmas are concerned, I read where all internal cards are made by the 3 companies. Are they size specific? As in, will I only find the same card as mine in a 50" tv or do they use the same cards in different size tv's? I can't imagine finding in a 19", but a 42"......55"?

[tom66]

Re: DP50747 Troubleshooting

The guide was written about a year and a half ago, I know a lot more about how a plasma display panel operates now.

The whole board or IC on each board needs replacing.

You wouldn't get a 19" plasma. A 21" prototype was developed by Fujitsu. LG produced a commercial 32".

And the boards are very rarely compatible between models; sometimes the Y-sustain/Y-main/SC or Z-sustain/X-main/SS is compatible between different size same main model code (common with Panasonic; they keep the same layout but add more components for bigger screen sizes because the power consumption is higher.)

[Twithers]

Re: DP50747 Troubleshooting

Are you saying that I will only find the right card in another DP50747? Or from the same model line? I'm trying to find another one with a cracked screen to pull the bad card from.

[tom66]

Re: DP50747 Troubleshooting

Is it using a Samsung, Panasonic or LG PDP?

[Twithers]

Re: DP50747 Troubleshooting

Lg

[tom66]

Re: DP50747 Troubleshooting

There's a sticker on it with something like PDP50R7000; what is the exact part# on this sticker?

[Twithers]

Re: DP50747 Troubleshooting

Pdp50x4ta35

[tom66]

Re: DP50747 Troubleshooting

Quite likely this is your part, though do check all part #s.
http://www.shopjimmy.com/lg-ebr39573901-ydrvtp.htm

[Twithers]

Re: DP50747 Troubleshooting

For my own info, what points you to the Y top card, if the cutoff isn't halfway?

You had mentioned a buffer board before? Which one is that? And what changed your mind from that?

Thanks for the help.

[tom66]

Re: DP50747 Troubleshooting

Buffer board is the same as the Y drive board.

I still haven't actually seen any pictures like I requested, so how about you post those so we can be sure before you order the wrong board.

[Twithers]

Re: DP50747 Troubleshooting

OK.

So far I need to post the fault screen picture. Was there anything else and i'll put them up together?

Thanks for the help.

[tom66]

Re: DP50747 Troubleshooting

That is all for now.

[Twithers]

Re: DP50747 Troubleshooting

Now, I'm concerned. I was searching posts again and I came across an identical fault, but as soon as the person posted a picture, all the help stopped. That's not going to happen to me, is it? I've been getting great help and wouldn't want it to stop.

https://www.badcaps.net/forum/showth...o+buffer+board

[tom66]

Re: DP50747 Troubleshooting

If you don't post a picture them maybe all help will stop too?