Samsung plasma pn50b550t2f power on/off

[bsickler]

Hello, i have a 50 in samsung pn50b550t2f. when i power it on it clicks to turn on, then clicks off. if i leave it plugged in it will continue to try to turn on then power off. I have unplugged my x sus and y sus and problem still remains. If i unplug the t-con board (aka logic board) it will power on but still no picture.

on my pcb i have all the proper voltage at the pins, stand by voltage ect. the only problem with voltages is the VA test point gets to 36 volts before the tv will power off, should be 58 volts. VS is 3 volts, ve 3 volts and vscan is 0, granted tv only powers up for a couple seconds.

no bulged caps, no burning smell, no signs of arcing. Im looking for guidance of where to go next. I was going to change out my PCB and/or logic board but i dont want to throw a bunch of money into this set. i read there is a small chance it could be the main board.
*A service manual would be ideal*

Thank you in advance everyone

[Kjelds]

Re: Samsung plasma pn50b550t2f power on/off

Hi bsickler,

I've just discovered that my own main board had a burned out processor. If you want to make sure its a main board issue, I'll recommend that you go through the two last steps in this video https://www.youtube.com/watch?v=JjrwTZC5nVg

Short the VSon with gnd (RTN) on the power cable running to your main board. Remove cable from logic board to main board and short the two highest pins on the logic board. Your TV should then run through test patterns on your screen and you have then confirmed the issue is the main board.

I would recommend http://www.electronica-pt.com/esquema/tv/ if you want to find a service manual.

[bsickler]

Re: Samsung plasma pn50b550t2f power on/off

Ok I just jumped PSon and disconnected the ribbon cable from the logic board and jumped pins 3 and 4 of the logic board. Powered it on and it still clicks on then off. So that tells me my main board is good. Is it fair to say at this point the power supply board requires replacement? Thank you for your help. I greatly appreciate it

[bsickler]

Re: Samsung plasma pn50b550t2f power on/off

Hey guys, looking into a new power supply, I can't think of anything else so I'm totally open to ideas from the pros on here. Any recommendations on a trusted company so indoor waste my time ordering a bad board? If anyone has any further troubleshooting ideas in game. Thank you

[bsickler]

Re: Samsung plasma pn50b550t2f power on/off

I totally forgot to load pictures! Hope this helps the chain. Thanks in advance

[Kjelds]

Re: Samsung plasma pn50b550t2f power on/off

Hi again bsickler,

As I'm not an expert in this matter, I can't say for certain, that it's PS issue, but at least the issue is still there, when you bypass the main board. So unless you are unlucky and have several issues with your TV, I would assume that the issue is the PS.
I've stumbled upon a lot of samsung click click PS videos on youtube (here fx: https://www.youtube.com/watch?v=quk9u7NoVbw) and it's usually caused by bad caps.

Bad capacitors are not always bulged up, some of them you can't see any visual damage to. You can either check your caps by measuring them (try searching on youtube on how to do this) or you can take a chance and order a new PS board on the interwebs. As I haven't ordered anything from any retailer of TV-parts yet, I can't really recommend any, but a friend of mine had success with https://spares2repair.co.uk. Otherwise there's a thread on this forum with recommendations.

[cliff_hootarski]

Re: Samsung plasma pn50b550t2f power on/off

Need good high resolution pictures of the entire back of the TV to see how things are connected. Also good well lit high resolution pictures of each board.
Picture of your multi-meter too or the model number of it.

[bsickler]

Re: Samsung plasma pn50b550t2f power on/off

As requested pictures of the boards. I appreciate you reply. its possible the gold colored cap on the PCB has a slight swelling, but it feels flat. This is my first time inside a tv, so my learning curve is high. ive learned a lot and im happy there are people out there who know what they are talking about. As a quick recap i disconnected the y sus, x sus and the same issue with the tv (ruling out those boards), if i try to start the auto gen test by bypassing the main board and jumping pins 3 and 4 of the logic board i have the same problem (ruling out the main board) that leavs the PCB and the logic board. I have not unplugged the touch panel and fired it up to see if the problem relives itself, but at this point im doubtful thats the problem. i have the correct stand by voltage, and the volt changes for the power on cycle are correct. I can not get an accurate reading of the Va, Vs, Ve, and Vscan because the tv is not on long enough. so it is possible that the PCB has a fault when it tries to power on, or the logic board has a fault. Again first timer here so please feel free to correct me in my troubleshooting if something i said seems off or wrong. thank you for your guys time.

[cliff_hootarski]

Re: Samsung plasma pn50b550t2f power on/off

In your first post, you say you disconnected the logic board and the TV powered up and stayed on but no picture. Could you recreate that scenario and measure Vs and Va voltages and post your results.

[bsickler]

Re: Samsung plasma pn50b550t2f power on/off

Thanks for your reply. Ok so I disconnected the logic board from the pcb. VA was 0 VDC and VS was 7.5 VDC. Bad pcb? I don't know the whole function of the logic board. I know it controls pretty much everything though. I thank you for your assistance.

[mmartell]

Re: Samsung plasma pn50b550t2f power on/off

Shorted ysus or xsus. Plug everything back in but now disconnect the ysus power harness and see if the set powers on and stays on. Of course you won't have a picture but not to worry....

[bsickler]

Re: Samsung plasma pn50b550t2f power on/off

With both x and y sus disconnected it has the exact same issue, it will click on then a couple seconds later power off. So I think the x and y sus are good. Thoughts??

[cliff_hootarski]

Re: Samsung plasma pn50b550t2f power on/off

With both Ysus and Xsus unplugged, try to measure the Vs and Va voltages when you first turn it on, before it clicks off. Probably need to use the Min/Max feature on your Fluke. Still trying to verify whether you have a bad power supply or it is shutting down for protection.

[bsickler]

Re: Samsung plasma pn50b550t2f power on/off

Thanks for the reply, so with both x and y sus disconnected I get a va of 25 VDC before the tv shuts off. VS measured 79 VDC. I noticed on the pcb it will click on and before it shuts down there is a faint tick tick tick tick tick then it clicks off. Don't know if that's normal or not. So does that reveal any light on the situation? Thanks again

[maxvalutech]

Re: Samsung plasma pn50b550t2f power on/off

From around 2011 if you disconnect y or z the set will automatically turn off via protection circuit. In that case y or z still suspect and more so y side. I would set up dmm to measure vs at turn on with all connected to see if around 190v shows at all.

[bsickler]

Re: Samsung plasma pn50b550t2f power on/off

My tv was built in 2009. Does that change the way the tv shuts down if your sus boards are disconnected? First time trouble shooter here. Also if I get 0vdc with everything connected then it's likely the Y sus? Which I also should change the y Buffer correct?
Thank you

[bsickler]

Re: Samsung plasma pn50b550t2f power on/off

Dec 2009

[bsickler]

Re: Samsung plasma pn50b550t2f power on/off

With everything connected the readings before the tv shuts down:
VS 30 VDC
VA 33 VDC
VE 12 VDC
VSCAN -113 VDC
I'm in over my head, thanks guys for your guidance.

[maxvalutech]

Re: Samsung plasma pn50b550t2f power on/off

The model year 2010 was the change re shutdown. Please search download Samsung Tech Talk vol 4 issue 11 for their brief on testing plasma voltages etc. Sorry as i only have basic phone for these posts so cant upload various refs etc.

[bsickler]

Re: Samsung plasma pn50b550t2f power on/off

Thanks, I reviewed a few different versions and got some ideas of testing for a short to grind through the vs. the main problem is the tv is only on about 3 seconds so reading my test points doesn't really help, unless I was getting a 0. So I'm going to test for a short to ground, test the y buffer for faulty chips. If that all checks good I'm going to just replace the pcb and go on from there if I need to. Input or ideas??