Samsung PN58B650S1F Power Board Clicks, No Picture

[WHaThEFLuX]

Just when I swore I'd never fix another TV, this monster plasma found it's way to my door. It's the classic power cycling, clicking relay, no picture kind of failure you guys love to figure out!

Threads for reference:

https://www.badcaps.net/forum/showthread.php?t=29327

https://www.badcaps.net/forum/showthread.php?t=27535


The curve ball with this set is that it could be anything, allow me to explain why.....


When I removed the back panel, the connector going to the front panel was disconnected from the main board, along with the speaker connection. Someone was definitely in there, making this my least favorite kind of repair, who knows what they did? Referring to the threads above, I began trying to pinpoint what had failed. When the set has power before cutting off, VS and VA are there(202 & 55). I disconnected the X and Y mains one at a time hoping for a change. Nothing, still clicking. Next up would be the main/logic board. Not having any of the correct value resistors to force power on without the main board, I had to get creative.(Don't judge me, it's not like I can go Radioshack anymore!)




When I Plugged in the set with the resistors in place, it powered up without clicking( LVDS and power connector from the main board were removed). No grey flicker or any sign of life from the panel. I jumped pins 3 & 4 on the logic board and crossed my fingers, but no test pattern was displayed. I decided to look over the SUS boards one more time to see if there was anything I missed. To my horror, I discovered that two transistors and 2 zener diodes had been removed from the Y board!



Now I'm at a loss because I have no idea what kind of repair was attempted. In a desperate attempt to make some kind of progress with this set, I pulled a similar samsung Y board from my graveyard, removed what I hope are the same value transistors and diodes, and soldered them on.

With the Frankenstein Y board back in the set, I repeated the panel test. This time whether or not the logic board was jumped, I got a grey flicker on the panel after power up, followed by grey snow at the top of the screen that slowly faded away. The panel does glow for a short time, then cuts off to black. I wouldn't mind throwing another main board in there since that seems to be the culprit, but the lack of a successful panel test has me weary. Could it be the logic board, the main board, all boards?

Help me O wise badcap veterans, you're my only hope!

[tom66]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

does the LED on the control board blink at 1 second intervals?

[WHaThEFLuX]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

Yes sir, there’s also another green LED on the control board that blinks briefly when I power up the set.

[WHaThEFLuX]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

Is it possible that I’ve replaced the components on the Y board with ones that have incorrect values, causing the panel test to fail?

[tom66]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

Yes sir, there's also another green LED on the control board that blinks briefly when I power up the set.

briefly, or every 5-7 seconds?

if briefly your CTRL board is not running for some reason - probably a shutdown.

check 5V supply to control board.
check VSON signal from control board to PSU.
compare this VSON drop using a second multimeter to Vs/Va drop - see if VSON drops then Vs/Va drops (scope can also be used for this purpose if it is a DSO)

[WHaThEFLuX]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

briefly, or every 5-7 seconds?

if briefly your CTRL board is not running for some reason - probably a shutdown.

Here's a video of the control board startup:
https://imgur.com/a/iIzmenR


There's 5V going to the control board.



By VSON signal I assume you mean voltage? If so it's 4.04V on the control board and the PSU.


Not sure how to compare the VSON - Vs/Va drop, could you elaborate on that procedure?

[WHaThEFLuX]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

It's also worth noting 3 things:

1. I went slightly "mad scientist" on the main board and removed the two EEPROM ics on the back and put them into a programmer(wasn't sure which one held the right information). One of them was a single line of code with ENG as a note, I'm assuming it's the language configuration. The other one was completely blank, I'm guessing this is the EEPROM that so commonly gets fried when the main board malfunctions.


2. I re-attempted the panel test in complete darkness. This time, I was able to see 2 lines of color on the panel in the upper left corner. They seemed to be changing color in a pattern, indicating that the panel test is functioning at some level.


3. I noticed that the transistors(or FETS, not really sure what they are exactly) I replaced on the Y board get hot way too fast when the set is on. I attribute this to either them being the wrong value components or the original issue with the Y board causing these components to cook. This would explain why they were removed in the first place, and also why the panel test is failing(or working in a very minimal way).



I went ahead and ordered a replacement main board since I think we can all agree that the original is toast, but the control board and the Y board still remain a mystery. If anyone can shed some light on what those components on the Y board are and their values, or how I would be able to find out that information it would be greatly appreciated. Lastly, if I plug all these boards with potential problems into the "new" main board, could I fry it like the original?

[Andrew F. Ali]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

With the X and Y Bds and disconnected the PSU may go in to recycling as the VS has no load. Use two 12Vac light bulbs in series as a load for VS with the X and Y Bds disconnected and see if the light up and remain ON. If the y do the PSU is probably good. Measure for the other voltages 15V, etc produced by the PSU to be absolutely sure.

[tom66]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

So is your Vs and Va staying on?
The single line possibly indicates that the Vsc_H voltage is not being applied to the scan buffers.
Check for Vsch, should be 150V.
You can check across where you'd normally check for shorted buffers.

[WHaThEFLuX]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

UPDATE:

I have now dubbed this project the “trail of fail”, although I did make some progress.



I was able to source the correct components for the Y board, once those pieces were in place I attempted the panel test again, and this time I was greeted with beautiful colors!


So I know the panel’s good now, and can assume that the sustain boards are functioning correctly. The original main board causes the power cycle, and the used ebay main board makes the set behave exactly the same way. I found a used control board for a whopping $7 and threw that in there as well with the same result.


I’m aware that there’s a good chance the ebay boards could be bad, but other than that I’m at a loss. Do I return the control and main board, then try my luck with another main from a different seller? Are there any other diagnostic tests I can perform that will give me some clarity?

[tom66]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

The main board was bad, have no fear in returning it.
If your control board does test patterns OK, keep the working one as a spare. I don't think you should return it if it's working, only if it's broken. Chalk that one up to a ($7) loss.

[R_J]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

Use two 12Vac light bulbs in series as a load for VS with the X and Y Bds disconnected and see if the light up and remain ON.

I think you forgot a zero, that should be two 120Vac light bulbs.

[tom66]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

I think you forgot a zero, that should be two 120Vac light bulbs.

yep, two 12V bulbs in series would make for an impressive pop if connected to a 200V source!

[WHaThEFLuX]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

So there seems to be no revision A boards available at the moment, I've been told that a revision D board is an acceptable substitute, but the BN97 number would not be identical. Will I be able to use this board?

https://m.ebay.com/itm/Samsung-BN94-...ty!10965!US!-1

[R_J]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

and the number on your board would be....
Shopjimmy, says BN94-02856D subs for BN94-02856A and BN94-02856B
for model PN58B650S1FXZA KU07
https://www.shopjimmy.com/samsung-bn...b650s1fxza.htm

[WHaThEFLuX]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

It’s been said in other threads that the important number to match is the BN97 one, in my case the original board numbers are BN94-02856A / BN97-03160A

[R_J]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

The important number is the one on the white sticker. not the BN41 or BN97 numbers, those are generic board numbers

[WHaThEFLuX]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

Thanks for clearing that up RJ. The new main board did the trick! Thanks to everyone for your advice and input, it’s much appreciated. The quality of this set is unbelievable, hard to believe it’s a decade old, I just might never leave my living room again......gotta love those plasmas!

[Andrew F. Ali]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

I think you forgot a zero, that should be two 120Vac light bulbs.

Yes it's supposed to be two 120V bulbs. Sorry for the typo..

[Hoanr]

Re: Samsung PN58B650S1F Power Board Clicks, No Picture

.Sorry for butting in this thread, I have a e series plasma TV made in 2012 by Samsung, it seems to have the same problem as yours, the stand by voltage and lights are all good, when I turn it on the vs and va voltages are perfect, but the logic board and red light all blink and the TV displays a flash then a snow effect then turns fully off, then it turns itself on again and does the same thing over and over until I unplug the mainboard from the power supply, I don't know how to force turn on the power supply without the mainboard.