DP50747 Troubleshooting

[tom66]

Re: DP50747 Troubleshooting

No. The boards are going to be totally and completely different.

[Twithers]

Re: DP50747 Troubleshooting

Originally, you had given me a Y upper part number from ShopJimmy of EBR39573901. The sticker on the actual board says EBR37397801. Is the 3901 an alternate part, and if so, how would I know that on ShopJimmy? Otherwise, does it have to be exactly the 7801 because that's what is inside the TV?

[tom66]

Re: DP50747 Troubleshooting

Only ShopJimmy can tell you that. Contact them and enquire.

[Twithers]

Re: DP50747 Troubleshooting

Update:

I replaced the Y upper board, and the TV is pretty much working as new. Thank you very much for the advice.

Ther are a couple vertical pinstripes that are not visible in all images. They are in fixed positions, but randomly dispersed through the screen. Roughly 5 of them.

I adjusted the "V" rheostats and it seemed to affect the intensity of the vertical lines, but they do not disappear completely.

I looked through old posts with similiar gripes and you had mentoined in those cases that it is not repairable. Would that be the same case for mine?

[tom66]

Re: DP50747 Troubleshooting

Can I see a picture of these lines?

[Twithers]

Re: DP50747 Troubleshooting

I tried to take a pic, but the lines are so thin (like 1 pixel wide) and they shift in and out of visibility.

I tried to get them to show up on the white screen, but I haven't gotten them to show up on a pic yet.

Is that white screen just for diagnostics or does it serve some other purpose?

[Twithers]

Re: DP50747 Troubleshooting

Found a screen that will show the lines well enough to get them to show up in a picture.

[Twithers]

Re: DP50747 Troubleshooting

Here it is.

[Twithers]

Re: DP50747 Troubleshooting

Update:

I took a shot at adjusting Vs and Va as per the plasma guide. The sticker calls for 193v Vs and 60v Va, but if I set it dead on, the vertical lines are very bright and defined. If I drop Vs 15-20 volts, just before the red sparklies show up, they fade out around 60%.

[tom66]

Re: DP50747 Troubleshooting

You probably have a defective plasma panel, this will not be repairable. Did you ever plug in any connector while the set was still energised?

[Twithers]

Re: DP50747 Troubleshooting

No

[tom66]

Re: DP50747 Troubleshooting

Did the lines appear before with the old buffer board in place? Do the lines stay fixed, or are they moving? What does Va measure?
I do think the panel is bad though, not sure what could have caused this if it was not there before and you did not plug in anything while panel was not energised.

[Twithers]

Re: DP50747 Troubleshooting

The lines could have been there before, but because I had a bad Y upper, I couldn't see the screen to tell if they were there.

If I put Va on 60vdc, as dictated on the sticker, the lines are worse. I have to drop Vs and Va about 10%, to get the lines to fade out about 60%.

The lines are always in the same place.

Could it be caused by the ribbon cables from the display to the Y upper being a little out of alignment in their connectors? I had a tough time getting them seated properly.

[tom66]

Re: DP50747 Troubleshooting

Can you post a picture of the whole chassis?

[Twithers]

Re: DP50747 Troubleshooting

Do you mean a picture of the back of the unit with the cover off?

[tom66]

Re: DP50747 Troubleshooting

Yes.

[Twithers]

Re: DP50747 Troubleshooting

Since lowering Vs and Va makes the lines less visible, is it in any way detrimental to leave the voltages that far off from the sticker voltage specs? In other words, if the lines can't be fixed, am I also causing more damage to other parts by running the voltages that low or will it be ok that way?

The picture is on its way.

[tom66]

Re: DP50747 Troubleshooting

Can't see any harm -- except as the panel ages you may get more misfires (dead/lit pixels) or maldischarge - pink/purple tinted clouds visible on pure white. I'm surprised you can reduce line visibility with lower Vs/Va.

[Twithers]

Re: DP50747 Troubleshooting

Yeah, if I put Vs and Va on the sticker specs, the lines are bright and solid. But if I lower the voltages to just before it goes red sparkles, the lines are significantly reduced and only really show up in certain color/image schemes.

Maybe that could be a tip for all those people who have the lines due to an irreparable display.