Samsung Plamsa turns itself off PN58B540S3FXZA

[HMRG123]

I have a Samsung Plasma that turns itself off just like someone used the remote; picture turns black, no sound, and a couple second later, the relay clicks and power turns off. When running, the picture is great; no lines or distortion.

This set was given to me by a friend and after several internet searches, I purchased a main board. This fixed the problem for about 4 months. Luckily I had a 2 year warranty on the board and received a second main board. This one lasted a few weeks before the symptom returned. Sometimes it will stay on for hours, sometimes only a few seconds. I just wanted to see if anyone had any ideas about something else I need to check. It is a PN58B540S3FXZA.

I had a similar symptom with my PN50A550S1FXCA but the board is different. I fixed with a Main board with a component repair kit but cannot find a kit for this set. I still have the original main board but no manual.

[Nick's Tvs]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

Take a look at your power supply. You more than likely have cracked solder joints on the power supply board.
If you can take an HD picture of the back of the power supply board with good enough quality so we can zoom in on it, we could let you know which joints are bad and need reflow. If I were you however I would probably just reflow all transistors that are on heatsinks since they generally will be the ones that run hot.

[HMRG123]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

Thank you for the reply...check out the power pcb and let me know what you see.

[Nick's Tvs]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

The second picture on the middle right side of the board has a joint that is either burnt or covered in flux. Other than that it looks like you already went over all the joints that could have cracks in the solder joints, or at least someone did, so its possible that maybe the issue is somewhere else. We just got a TV in the shop today 60 inch LG with similar issue with the picture going away after 10 to 15 minutes but the sound was still there and it had cracked solder joints all over the sustain boards. But since the entire TV turns itself off, I am thinking it has to be either the power supply or the main board indeed.

Where are you getting the main boards from?

[HMRG123]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

I'll get that board off tonight and check that point. I got the Main PCB from ShopJimmy

[dskall]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

What is the voltage across the main capacitor on power board?

[HMRG123]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

Checked the solder point...it was covered in flux. The connection is good.

dskall... which one is the main cap?

[dskall]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

The three in the center. You will need to trace back of board to see where you can read across the caps from the top. Need to read the dc voltage when tv is working. These are high voltages so use care.

[swaysway510]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

I am having the same problem well not me but my friend who I gave my old tv to. same model. If you leave it unplugged for a little while and start it up it stays on for a few hours but once it turns off once the gap between the cycles gets shorter if you keep powering it back on. Last time I was over I checked the caps visually but all looked ok.

I hope you fix yours and maybe I can pin point the problem on my friends.

[Nick's Tvs]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

Honestly at this point we need to take a few steps back and consider the possibility you have a good power supply and a bad main board.

I have taken a look at the main board used in this tv from pictures off shopjimmy, and I am not sure I would know how to fix it on a component level, but they do have some for sale for $40. I would suggest performing a bypass on the power supply and see if that stops the cycling.
You will need to disconnect every single board from the power supply, all connectors and short the following lines together

PS-ON to ground
And
VS-ON to 5v line

If the cycling still occurs or if the VS or VA line fluctuating aka not steady then we definitely have a bad power supply but if the VS and VA lines are steady and holding the entire time, then you have a bad main board again.

[HMRG123]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

The voltage is 396 across the main capacitor on power board...working on the bypass setup now.

[HMRG123]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

The sticker says:
Va = 55 and measured 53.9
Vs = 198 and measured 199.2

These were taken with PS on (using bypass method listed above) and are stable.

With everything connected, the 5.3v measures 5.1 and with VS-ON measure 3.2
Are these within tolerance?

[HMRG123]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

Ok, got an idea to disconnect the connector going to the IR sensor after I turned the set on; no luck..shut down
Disconnected the cable going to the touch pad after turn on; no shut downs. Looked up the part number BN96-12641D to find this a problem with Samsung sets; the touch pads become highly sensitive. Replacements are difficult to find and removal from the set is difficult because it is glued to the front bezel.

I traced the runs and removed the Blue, Green, and Yellow wires from the connector at the Main PCB (and taped) to kill the touch function. Leaving the other wires intact, keeps the LED and IR sensor working. Since I rarely use the touch pad buttons, I won't miss their function.

[m2das88]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

Hi all , i have a similar problem with model 50PB5600.

So i purchased this tv from a gentlemen as a repair project.
He has previously replaced the main board as the HDMI port got broken.

When i got home i started running some voltages tests and all the boards get the correct voltage.
When plugged in the Tv will go into stand by mode and with a remote will turn on.
The screen will then give a sharp bright grey flash and then will dim right down to a very dull grey.
You can see in the dark that the tv is still lit (although faint).
From here i can not turn the tv off with the remote.
I cant get any sound menu or any of the components from the main board to work.
The Logic board blinks 4 times then does another 4 blinks and so on ..

My first guess would be the main board that is causing the problem.
I get this model is a pain in the a**
Id like to repair but at the same time not waste money on differnt boards..

any advice or input would be great

regards

[kca]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

Hello HMRG123 ~

Hope this finds you well. I read over this entire thread and I'm wondering if your fix as described in Post #13 (the wires to the IR sensor) actually fixed your issues. Was that the only thing you had to do, or did you end up replacing either the Main Board or the Power Supply Board?

Asking because I am experiencing something very similar on a 60" Samsung plasma. Any insights you can provide would be greatly appreciated. Thank you.

~ David

[HMRG123]

Re: Samsung Plamsa turns itself off PN58B540S3FXZA

Yes, it fixed the shutdown and occasional turn on's. The only thing that does not work is the keys on the front do not work. The remote works fine. I found out later that there may be a diode problem with the touchpad board, but I cannot find any details as to the fix.