Samsung PS43D450 Plasma - Very strange VS and VA?

[overlord]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

Heh, I was hoping for some voltage regulators... but nope. I don't know what could cause it, sorry...

haha me too :P do we think the problem lies within this board?

[tom66]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

I'm about 70% sure the control board is at fault. Someone else had a problem with this set not powering on, and it turned out to be the main board. However your set does power on with a flicker from the screen.

https://www.badcaps.net/forum/showthread.php?t=21740

There is one more test we can do to see if the control board is faulty, we can try and get it to generate some test patterns. The 4 pin test jumper, the user above reported these with a FAULTY main board and WORKING control board:

Jumpered 4-2: Backlight (or plasma equivelant) would fire on for about 4 seconds then go off.
Jumpered 3-1: Backlight (or plasma equivelant) would fire on for about 4 seconds then go off.
Jumpered 2-1: Display would power on, show all gray for about 4 seconds, then go off.
Jumpered 4-3: This was the good stuff! Showed all types of test patters and then would loop itself indefinitely.

If you get similar results, then maybe the control board is OK.

[overlord]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

I'm about 70% sure the control board is at fault. Someone else had a problem with this set not powering on, and it turned out to be the main board. However your set does power on with a flicker from the screen.

https://www.badcaps.net/forum/showthread.php?t=21740

There is one more test we can do to see if the control board is faulty, we can try and get it to generate some test patterns. The 4 pin test jumper, the user above reported these with a FAULTY main board and WORKING control board:

Jumpered 4-2: Backlight (or plasma equivelant) would fire on for about 4 seconds then go off.
Jumpered 3-1: Backlight (or plasma equivelant) would fire on for about 4 seconds then go off.
Jumpered 2-1: Display would power on, show all gray for about 4 seconds, then go off.
Jumpered 4-3: This was the good stuff! Showed all types of test patters and then would loop itself indefinitely.

If you get similar results, then maybe the control board is OK.

In three of the jumper configs above, i get nothing at all on the screen - in one of them i get a decent amount of white-lines-flicker (really fast for maybe a second) and thats it.

I'm thinking its worth the ~$30 of ordering a second hand control board like this one:

http://cgi.ebay.com.au/ws/eBayISAPI....MakeTrack=true

and even though the part numbers dont match exactly, i think it will be fine...

LJ92-01793A vs LJ41-09475A

Actually they are a bit more different than i thought they would be... but they are from exactly the same model of tv...

What do you think tom?

But - seriously - thank you so much for the help with diagnosing this, it really had been such a big help

[tom66]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

If you can get it for £12, go for it! That's a good price to take a chance on - the only other board I think it could be is the main board.

Since you get brief flickers but they're not correct, I suspect that the panel is fine, and the control board is a dud.

[overlord]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

If you can get it for £12, go for it! That's a good price to take a chance on - the only other board I think it could be is the main board.

Well considering i've got to contact the seller to post it to down here in australia it might be a bit more... :P

Thanks mate - hopefully i can report back in a few days (or weeks based on postage haha :P ) and tell you how its going

Thanks again

[tom66]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

See if it ends up cheaper to ship it from a company like this:
http://flattvparts.co.uk/index.php?m...ducts_id=11950

No Aussie TV scrappers? You could also try getting a similar model with a cracked screen and gutting it for the boards.

[overlord]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

See if it ends up cheaper to ship it from a company like this:
http://flattvparts.co.uk/index.php?m...ducts_id=11950

No Aussie TV scrappers? You could also try getting a similar model with a cracked screen and gutting it for the boards.

Not that i can really see or find... thanks for the link - will see how much postage is first from ebay and go from there

[tom66]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

Good luck let us know how it goes.

[overlord]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

Okay little update on man vs plasma

New Controller board, still no real difference on the screen.... but all of a sudden i have sound and full remote control? It seems as if i've fixed SOMETHING at least!

I also remember that i never checked any fuses on y-sus or x-sus, nor where to find them...

Also, Vsc is correct on y-sus, -185v - but something is still cutting Vs and Va, some sort of protection mode for something perhaps?

Any feedback would be helpful

Thanks!

edit: looks like all the 15v and 5v lines are close to rated - i mean the thing is on and working - hopefully this doesnt mean the panel is cracked!

[overlord]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

OKAY

As long as both of the ribbon cables from the controller board, one going to x-sus and the other y-sus are DISCONNECTED - Vs and Va switch on and stay at rated levels? VS_ON stays high at 3.25v. If either of these ribbon cables are plugged in the Vs and Va dropping levels occur, as does Vs-ON drop to 0v (the psu bounces back after one of these ribbon cables are hotplugged then removed, so im guessing the psu is good)

Faulty Panel or sustains - or buffers? Hell what isnt broken haha!

Remember this is a small crack in the front, but looking on the edge of the screen (as the bezel is a bit off at the moment) i can see what appears to be a layer of protective glass in front of it...

[tom66]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

It could be a bad panel, but I very much doubt it, because you have a flickering screen. It's possible your control board is shutting things down if it doesn't like what it is seeing. I really am not sure - sorry!

[overlord]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

It could be a bad panel, but I very much doubt it, because you have a flickering screen. It's possible your control board is shutting things down if it doesn't like what it is seeing. I really am not sure - sorry!

No worries mate, im at a loss to whats wrong with it now too...

[Max_007]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

hi, am new to this forum. Dont know if this is the right place to post my query. Correct me if i am wrong ;-)

I too have a Samsung plasma tv PS43D450A2 model with horizontal black lines in the middle part of the screen. The tv is fully operational.

The voltages on all test points of the power supply, y-main board test points read fine according to plasma screen stickerwith Va, Vs and Ve readings. The X main voltage at test point XS-E is 78V

But when i test the voltages across the smd resistors R5149 to R5154 and smd zener diodes D5504 to D5506 (marking PJ1389) on the Y-buffer board, i found that the voltage is fluctuating between 45V and 30V. It keeps dancing up and down on all the resistors and diodes across the y-buffer board.
I felt the ICs on the board with my fingers and they were all warm. Nothing too hot or cold. Is this a voltage regulation issue from the y-main board or a y-buffer board issue? Little confusion here ;-) The heart beat on the logic board is good. I have tried re-seating
the flex cables on the y -buffer too. The only thing bothering me is the fluctuation in voltage across the resistors/diodes on the y-buffer board.

Could it be bad capacitors on y-main board? But the test point voltages on the y-main read ok. So the confusion haha.
Any feedback will be really helpful. Thanks n regards?

[sordids999]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

A picture of the fault would help also you could try test patterns to see if its the panel at fault

[Max_007]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

Hello, thanks for the reply sir.
Sorry for me replying late as was not well so this TV repair project was stalled.

Anyways, I have attached pictures for better understanding.
I mostly suspect the Y-buffer or the Panel itself to be bad. I have ordered a new y-buffer board to test the same before i trash the tv.

The voltages across the resistors/diodes on the y buffer should be typically 58V but its way low to 41V and fluctuates on the lower side till about 28V or so.

There are no shorts on the y-buffer board and i checked for that. One thing i did notice though, that the diodes are conducting in both directions i.e. i get a beep, although the sound is little low on the multi-meter buzzer. But it should not do that. What's puzzling is how can all the diodes behave in that same manner. The smd resistors marked 470 measured 32 ohms on the multi-meter. More than 20% lower here. I am really curious to test the new y-buffer board that i ordered and compare the resistor and diode readings.

It will be some time before the new board arrives. I will keep you posted.
Thank you. If you have any ideas, do let me know.

best regards

[dick_barton]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

I think you need to double check that all the Ybuffer ribbons are located correctly into their sockets. The one in the picture does not look right.

[tvtimmy]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

+1

[Max_007]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

Thanks dick_barton and tvtimmy for your observation. Will do a cross check once again. Althogh i tried re-seating the cables many times. No harm in re-checking i guess.

regards

[dick_barton]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

You need to be patient to reseat the ribbons carefully into their respective connectors and then double check that they all look identically seated. Sometimes this has to be done several times. Any ribbon not in place will give you lines across the screen or may even damage the buffer chips.

[pin6pts]

Re: Samsung PS43D450 Plasma - Very strange VS and VA?

Hey, really hope I am not going to upset anyone by doing this wrong but here is my deal. I can't seem to post a new thread for this even though have done the required reading of new messages and PM.

I have a Samsung plasma PN59D7000. While watching tv, all of a sudden it turned off. I don't recall a popping sound nor was there any burnt small. The set won't turn on at all. If I unplug the power and plug back in I get a single click, the initial red standby light for a second, then get 5 flashes from the red standby light. But it never turns on. Hitting the power button does nothing, holding it down for a while does nothing. Pressing every other button e.g. volume, channel, I get a blink of the red standby light. There is no audio either. Checking the VS and VA voltages I get nothing on the test points of the power supply board. Plugging the power in and checking those test points again they are charged but then quickly drain to zero. I do get 5V standby on the 6 pin connector from the power board to the logic board. So far the only thing that makes any changes to the above is when I disconnect the ribbon cable from the logic board to the y-main board. When I do this, I get full 217 Vs and 55 Va voltage on test points of power board, pins of y-main board and x-main board, I get standby 5V as well as VS-ON at 3V. Also, when this ribbon is disconnected I am able to hold the power button and the tv attempts to start-up but clicks once; the same as the initial plugging into the power supply, and then a little different sounding click a second later. Nothing turns on though. Assuming the y-main board and two y-scans (upper and lower) are the issue I replaced them with the exact matching parts from shopjimmy. To my disappointment there is no change to the above. The logic board has the green LED 2000 lit or flashing through all of this as well. However, when the ribbon cable is connected from logic board to y-main board, I get a solid green for 5 seconds and a 1 second off. When the ribbon is disconnected I get steady 1 second flashes on and off.