Samsung PN50B430P2D

[martino]

Hello again....
Waiting for parts for my other projects,so figured I would start on this one.
When turning on it just clicks and you can hear the power supply "grunt" and click till it gives up completely..
Disconnected the Y-board and TV turns on normally(no pic of course).

Y-board is a BN96-09738A. I measured the pins from plug CN5002 and there is a full short between pin:gnd and pins:Vs.
A search explains me that it's very common for these boards to fail,yet I can not find a schematic for it,even looked in TOM66 list.


Does anybody have a schematic for this board? Or even a "AH,ya I fixed a board like that,it was so and so"?

[tom66]

Re: Samsung PN50B430P2D

No schematic but a "HA!" I fixed it...
https://www.badcaps.net/forum/showthread.php?t=18434

[EsqzMe]

Re: Samsung PN50B430P2D

Hmmmm....PN50A550S1F with same kind of symptom. Found 1 swollen/leaking cap on Y Main board. Everything else looks nice and neat. Replaced that cap but no joy.

Plug the power cord in and relay clicks multiple times, standby light comes on, then stops clicking and light goes out. 1 green LED on the power supply board begins to blink in sequences of 7 times, repetitively.

I'm going to try unplugging the Y board. I should start another thread?

[tom66]

Re: Samsung PN50B430P2D

A new thread would be a good idea.

[martino]

Re: Samsung PN50B430P2D

No schematic but a "HA!" I fixed it...
https://www.badcaps.net/forum/showthread.php?t=18434

Awesome,I was probing the fets on the first heat sink(see pic) as tracing the board revealed those are directly connected between ground and Vs(besides a bunch of caps). They both test shorted on all pins while in place. Picking up some more solder sucking wire as I ran out to test them out of circuit.

Tom66,how did you find that thread? I searched this forum for a long time,didn't find anything (wanted to prevent to start a new thread on a already solved problem)...

I also fly model air planes,lol

[tom66]

Re: Samsung PN50B430P2D

I found it because I remember that user had the same board. Their TV was a 450 series though.

Model aircraft flight with FPV gear is one of my pastimes, though I don't do it as much now I am getting back into the hobby. (Moved to a city landscape with no fields within 3 miles, but that's since changed.)

[martino]

Re: Samsung PN50B430P2D

So,got the fets FDA59N25 out and sure enough one was shorted.
I decided to replace both of them,just to be sure.
Now the TV does turn on and I can get the menu up etc BUT the picture looks like this(see pic)....
Does this look Y-board related to you guy's?

[tom66]

Re: Samsung PN50B430P2D

Try the test pattern mode on control board
https://www.badcaps.net/forum/showpo...61&postcount=2

It looks like either the Yfr pulse is stunted or the X-main is bad too. I think it's more likely to be a Yfr pulse issue than anything else because that part could have been damaged when one of those FETs failed.

[martino]

Re: Samsung PN50B430P2D

Will try test patern in am.
Yfr almost makes sense already cause around that area I can hear a bit of buzzing. If test patern gives same result(as I think it will) then I'm gonna check all the other fet's on the Y board.

[martino]

Re: Samsung PN50B430P2D

so,found 2 more transitors that are shorted out....
They are fun ones:RJH3044 9612.
On the hunt for those through "my parts guy" as they seem to be a stand alone kinda transistor and can't be substituted for something of the shelve,ugh...

Also double checking the 2 fets I replaced,at first glance it looked like they where soldered only on the bottom side of the board,but now it looks to me,that some pins are soldered through the board to the component side,even though it barely showed solder on the top side...schematic of the board would have been super handy now as the replacing of the fets turned a bit into a butcher job(had trouble getting them off the board)..
Will post results when I get my paws on those transistors

[martino]

Re: Samsung PN50B430P2D

found this tv back under the workbench,figured I would start a 2nd attempt to repair this one.
Took some more pictures hoping you guys have some input.
Last two pics are while in test pattern,the light spots do seem to move when a scrolling pattern is on.

[gdawg]

Re: Samsung PN50B430P2D

I have the same issue with the same model #. Just wanted to post my results. When I got it, it would not stay on. I found a shorted x-main board which I repaired with a Shopjimmy kit. The tv then turned on, but had the image like you posted. Looks like maldischarge. So frustrated, I started freeze spray on different parts of boards. I hit the main chip on the logic/digital board and picture was perfect. Lasted a couple minutes and then returned to original display. I bought a new digital board all proud of myself that I found the problem. Didn't fix it. Identical to the original. I don't return boards for a refund cause I think its the cost of learning. I checked for cold solder joints on the y and x boards and nothing. So I ordered an X-main thinking that was the original problem, so waiting for the board and will report when installed. You guys are way over my head when Tom66 talked about Yfr pulse or something and of course I don't have a scope or if I did, probably would not know how to use it.!!

[martino]

Re: Samsung PN50B430P2D

really??? Interesting,gonna try that in a sec here. With digital board,you mean the little logic board,correct? (not the mainboard)
Maybe you should have returned the digital board as it was probably also defective. (freeze spray same effect on "new" board?

Trust me,when Tom starts talking about the Yfr,its over my head too,but very eager to learn.

[gdawg]

Re: Samsung PN50B430P2D

Yes the small board in the middle. Not the main board. I didn't return it cause it did the identical same thing, no change. I think by freezing it, I was changing electrical characteristics enough to correct what ever is wrong down stream. I ordered the x-main only because it was $12.00 shipped and wanted to rule out something deeper is wrong with x main. I should get it this week and will report. I don't have all the equipment I need to test tv.s, but I can solder like a SOB.

[gdawg]

Re: Samsung PN50B430P2D

Well my $12.00 X main board did not fix it, which tells me that I did repair it properly. It was shorted to start with. I hope I can get some guidance from Tom66 on the Yfr pulse. I did see a large transistor mounted to a heatsink on the Y sustain that was marked Yfr. I was going to check the obvious diodes and resistor in that circuit, but any help would be appreciated. I hope you don't need a scope to check that cause I don't have one. Thanks

[ReeceyBurger123]

Re: Samsung PN50B430P2D

Ever fix it matey ? Got the same on X main blew up then the Y main after I fixed the X lol

[martino]

Re: Samsung PN50B430P2D

Nope,while playing with it I could see pretty bad burn in of the screen and decided to pull the plug and part it out.

[ReeceyBurger123]

Re: Samsung PN50B430P2D

Noooo lol I have one here same fets blown as yours thinking the controller for them is bad too so changing that as well.

[mmartell]

Re: Samsung PN50B430P2D

I have one of these and repaired the Y with an ebay kit but when plugged in BOOM blew a fet on the lower heatsink. Keep us posted Reecey

[ReeceyBurger123]

Re: Samsung PN50B430P2D

Ok will do, hopefully I can sort it my buffers are testing fine so I know its just the Yfr circuit playing up.