Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

[lookimback]

I VA and VS in specs with the panel sticker. I have no way to know if there's sound or not. My only AV source is HDMI from my laptop. The back story I got from the previous owner is that his kid kept clicking the power strip on and off for about a half hour and finally, the TV wouldn't turn back on (I'm shocked that someone would let their kid play with a power strip, as if it were a toy). It clicks on, I get a momentary flash on the screen, and then about a minute later it cycles off and back on. It will do that repeatedly. My guess is that it's a sustain problem. I checked all the MOSFETs and IGBTs on both the X and Y sustain boards, albeit without removing them, and find none to be shorted. Disconnecting either sus board makes no difference. Both sustain boards are expensive, so I'm looking to do component level repairs. I'm guessing it must be one of the ICs on one on the sustain boards. Any ideas? I can upload any pics necessary later. For now, I have the one of the TV with the back off so you can at least see which version it is.

[tw2005]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

May be worth trying isolating the main board, jumper the logic ctrl board for the test patterns and force the PSU on.

[lookimback]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

How would I do that?

[tw2005]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

Bugger, I was hoping you knew. What's the part number of the ymain? I'll have a look and cross it to a samsung although I think th eprocedure is fairly generic. better look at the logic board number too as I think some have 4 or 6 jumper pins.

I've never done it but it does get mentioned here a bit.

[lookimback]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

Samsung BN96-09736A (LJ92-01600A) X-Main Board

Samsung BN96-09738A (LJ92-01601A) Y-Main Board

Samsung LJ92-01617B Main Logic CTRL Board

Sanyo J4FE (1AA4B10N22900) Main Board

Samsung BN44-00274A Power Supply Unit

Panel Sticker Number S50HW-YB04


Y main repair kit contents
https://www.badcaps.net/forum/showth...hlight=dp50749

[tw2005]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

looking like,
PN50B430P2DXZA, PN50B450B1DXZA

Also read clicking on/off could be protection cct.

I was thinking along the lines of corrupted eeprom if the kid was repeatedly plugging it in and out?


pg25 for forced operation

[lookimback]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

I'll try that in the morning. If it's the eeprom, that would be on the main right? Can it be fixed(reprogrammed), or would it have to be replaced? (the eeprom not the entire board)

[lookimback]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

This? http://www.ebay.com/itm/DP50749-with...item2a49b0d894

The symptoms in the description sound just like it too.

[tw2005]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

Could be, I really don't have enough knowledge on these but yes does sound like that. Still could be other things I guess. Gives you a couple of areas to check i hope. I have removed and replaced same type of chip on a panasonic by hand with aid of heaps of flux and jewellers loupe. Difficult for my eyes but manageable.

See how you go, maybe you'll get some other input from the regulars.

[lookimback]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

You definitely just taught me some stuff. I've done a lot of micro soldering by eye. I'm sure I can nail this. Removal is more of an issue. I have the hot air station though. It's always that dang adhesive under them that screws me up. Patience is the key.

Off topic but I've always wondered if, on the Sony Bravias where you have to match the main board to the serial number range, if the firmware on the eeprom is all that's different. Tried to change one once, but was foiled by that adhesive. Ended up peeling the tracings.

[tw2005]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

You definitely just taught me some stuff. I've done a lot of micro soldering by eye. I'm sure I can nail this. Removal is more of an issue. I have the hot air station though. It's always that dang adhesive under them that screws me up. Patience is the key. I've always wondered if, on the Sony Bravias where you have to match the main board to the serial number range, if the firmware on the eeprom is all that's different. Tried to change one once, but was foiled by that adhesive. Ended up peeling the tracings.

you're right, removal keeping the traces intact is the risk. I expect with hot air it should be easier. I don't recall adhesive issue with Panasonic, god knows with what you have.

$30 for the chip I guess is cheaper than a board.

[lookimback]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

Sanyo is a Panasonic brand. But I have found that adhesive on other Sanyo boards, so it's probably there. I've gotten a lot more practice since the last time I tried to remove such a chip.

[tw2005]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

it's great to explore smart ways of fixing things that would normally be just tossed out. look forward to reading what you find out.

[lookimback]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

I will definitely post back my results. That's my biggest pet peeve, people getting help and then not posting results. I like to post information which would have helped me, had it been here already. The first thing I do when I get a new project is come here and see if someone else has already solved the problem. That, and I look for repair kits which point me to a good place to start.

[lookimback]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

Ok, I couldn't sleep. I got up and tried it. I used a jumper from an old doorbell button. It works. So it's definitely the main. Thanks.

Edit: its a little sparkly on certain test patterns, but I'll address that after I fix the main if they persist.

[tw2005]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

Ok, I couldn't sleep. I got up and tried it. I used a jumper from an old doorbell button. It works. So it's definitely the main. Thanks.

Edit: its a little sparkly on certain test patterns, but I'll address that after I fix the main if they persist.

Hmmm,' I'm a bit like that myself. saves me waiting, I was very curious to see how that went. Well, that narrows it to one board, fingers crossed the flash chip it is

[lookimback]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

Yeah, I've never been able to sleep with something on my mind. I ordered the chip already. Should have pulled the old one first probably, but I'm confident. I'll lift 1 pin at a time if I have to. It's not like I'm trying to save the chip.

[tw2005]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

Yeah, I've never been able to sleep with something on my mind. I ordered the chip already. Should have pulled the old one first probably, but I'm confident. I'll lift 1 pin at a time if I have to. It's not like I'm trying to save the chip.

A sharp blade and carefully sever the pins hard up against the casing, remove the body then desolder what's left. A bit risky if the pins move and tear but done that on a 16 pin ic and a buffer IC. maybe an exacto blade. best left to you though. I 'd hate to suggest something and hear it went bad. The one I did I flooded the pins with solder and heated both sides at once but too much heat and those traces lift easy. I suspect you'll have more experience at this than me anyway, you seem to have a never ending supply of Tvs(lucky you)

[lookimback]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

I wish I really did have a never ending supply. Lol. This is my third fix today though(diagnosis anyway), credit to you on this one though. First 2 were inverter transformers, and replacements available for both. They come in waves. Couple weeks I'll only find a couple, then bam, 7 or 8 in one day. December, I think I only found 2. I post ISO ads in FB groups, most people have them and don't even know they have value. I get more with broken screens than anything, but parting them out allows me to have money to fix others. I really enjoy this work. I'm planning on going to college for EE in a couple years.

I pulled the IC. There was a small cap real close to it so I pulled it to avoid damaging it. That took longer the the IC. No adhesive. Hot air made it lift right off.

[tw2005]

Re: Sanyo DP50749 (Samsung PDP version) No picture. Screen tries to light.

I wish I really did have a never ending supply. Lol. This is my third fix today though(diagnosis anyway), credit to you on this one though. First 2 were inverter transformers, and replacements available for both. They come in waves. Couple weeks I'll only find a couple, then bam, 7 or 8 in one day. December, I think I only found 2. I post ISO ads in FB groups, most people have them and don't even know they have value. I get more with broken screens than anything, but parting them out allows me to have money to fix others. I really enjoy this work.

I pulled the IC. There was a small cap real close to it so I pulled it to avoid damaging it. That took longer the the IC. No adhesive. Hot air made it lift right off.

I hope you sleep between now and when that chip arrives

It was a hunch and a guess although reading the posts now for a couple of years you get a feel and some interesting stories. Still assuming it's that chip.

you seemed pretty keen to attack the sustains but I always like to try the isolation tests just in case and you said voltages were normal, no shorted transistors and a flash of the panel. That test seemed a good idea and no cost!