DP50747 Troubleshooting

[Twithers]

Re: DP50747 Troubleshooting

Here's the pic. Looks very similiar to the pic in that post I linked.

[tom66]

Re: DP50747 Troubleshooting

The bottom of the screen that's not working still glows?

[Twithers]

Re: DP50747 Troubleshooting

Yes

[tom66]

Re: DP50747 Troubleshooting

It would appear to be a buffer board fault then.

[Twithers]

Re: DP50747 Troubleshooting

Is there any way for me to further verify that?

The buffer board, meaning the Y upper or the Y sustain?

[tom66]

Re: DP50747 Troubleshooting

Do you have access to an oscilloscope?

[Twithers]

Re: DP50747 Troubleshooting

No O-scope. Just a multimeter and an unhealthy lack of respect for 300 volts.

[tom66]

Re: DP50747 Troubleshooting

Unfortunately then there's not much you can do.

[Twithers]

Re: DP50747 Troubleshooting

Ok. Before I order the board, I wanna make sure I'm on the right page. The picture of the part on the link you sent me looks like the Y upper. Is that the board you are suggesting is faulty or is it actually the larger Y sustain card?

Just so I'm picking up what you're putting down.

Thanks again for all the help.

[tom66]

Re: DP50747 Troubleshooting

The Y-buffer upper, Y drive upper are different names for the same part.

The Y-sustain or Y-main is a different part. The Y-sustain appears to be OK, because you have at least some image.

[Twithers]

Re: DP50747 Troubleshooting

Good deal.

Thaanks for all the patience/help.

[Twithers]

Re: DP50747 Troubleshooting

I have one more question.

If the part number that on the order link you sent me (EBR39573901) is different than the one actually printed on the board in the tv (EBR37397801), which one should I go with?

[tom66]

Re: DP50747 Troubleshooting

Ideally, the one on the TV, though ShopJimmy may be able to tell you if the board is compatible, if sourcing an *801 is too difficult.

[Twithers]

Re: DP50747 Troubleshooting

ok, only one more.

If I understood correctly, the "good" part of the screen (the very top edge on mine) corresponds with that buffer on the card, does that mean that all the buffers on both upper and lower cards are bad except the buffer that corresponds with the "good" part and that "both" upper and lower buffer cards should be replaced?

If I'm way off, I apologize, I'm a bit slow.

[tom66]

Re: DP50747 Troubleshooting

Each buffer IC chains a signal from one to the other.
So top buffer IC is OK. But second one isn't. And this isn't sending a signal to each of the others.

[Twithers]

Re: DP50747 Troubleshooting

Would I need to start a new thread to ask you about the set in the picture?

Apparantly the picture and sound play fine, but it has those 2 stripes in the way.

[tom66]

Re: DP50747 Troubleshooting

Yes. New thread. Defective CTRL board or bad plasma panel.

[Twithers]

Re: DP50747 Troubleshooting

Hey Tom, the buffer ICs you mentioned earlier, are they located individually under their own aluminum heatsinks? So that there are 5 in a row on that upper card?

You were saying that the fault should lie in the path between that first buffer IC (because there is video in that corresponding sector) and the 2nd IC (because that's the corresponding sector where the fault starts) or the 2nd IC itself.

If I understood that correctly, in your experience:
1. Is it ever a matter of a solder/reflow issue?
2. Is it very likely that only the one path or IC failed causing the fault?
3. Or is it more likely that the cause for one failure caused multiple ICs to fail?
4. And is it likely that I should be shopping for the Y lower also? And the Y sustain also?

Thanks for taking me to school today!

[tom66]

Re: DP50747 Troubleshooting

Depending on the design they are sometimes heatsinked, sometimes not. Each buffer IC is a separate, multi-pin chip. The chip contains a shift register, latch, and high voltage output switching (64 to 96 channels capable of switching ±200V signals.)

1. I have never seen such a fault on the buffer board.
2. Yes.
3. It would be unlikely.
4. No, only the Y upper buffer at the moment.

[Twithers]

Re: DP50747 Troubleshooting

Hey Tom,

I've got a followup question on this thread:

I'm picking up a Samsung PN50C550G1FXZA that took a hit to the glass and cracked the screen.

Do you think I'll either be able to use a combination of boards from the Samsung to fix the Ybuffer problem on the Sanyo or the Sanyo screen and all the cards from the Samsung to make one good TV?