Samsung PN50A550S1F shutdown

[debaser]

I've got a Samsung 50" plasma model PN50A550S1F that I've owned for about 4 years and have put alot of hours on it. For a few months now it's been having issues when I first turn it on. It will come on and then shut down after a few seconds and repeat this until it will finally stay on. Then I have to wait a bit before sending a signal to it or it will start power cycling again. Today it would turn on but no picture and then a few seconds later it would turn off and then back on again (relaying clicking) and just keep repeating this.

After reading some very useful information on this forum, it sounded like my power supply or main board could be the culprit. So I started with the power supply board. No blown fuses or smoked components. There was one cap that was bulging a bit at the top but when I checked it with my ESR meter it wasn't too bad (I've measured brand new caps with the same uF that showed the same level of ESR as this one). I will probably replace it anyways for good measure.

In between shut downs, I measured the voltages at Va and Vs and both were right where they should be (57v and 204v respectively). So I unplugged everything from the power supply except the incoming AC and connected a 220ohm resistor from PS-On to GND and another one from VS-On to 5.3v. When I did that, the power supply fired up and the relay clicked and it stayed running without shutting down. Va and Vs voltages were good as well. From what I can tell the power supply is fine.

So, does this sound like the problem is with my main board? Seems to be a common issue with this set. If so, any recommendations on a reputable place to buy one?

Thanks!

[debaser]

Re: Samsung PN50A550S1F shutdown

So I reconnected everything to the power supply except the cable going from the power supply to the main board. I still had a resistor tied from PSon to GND. I plugged in the TV and I get the relay click once, the Vs and Va voltages are good and it doesn't shutdown. If I push the power button on the TV it does nothing. I also don't hear the Samsung jingle when I plug it in. Is this normal if the main board is not connected? I'm assuming so.

Is it possible to trigger a test pattern and by passing the main board to see if everything else is ok? If so, how would I go about doing this?

[cliff_hootarski]

Re: Samsung PN50A550S1F shutdown

Search for this topic:

"Samsung PN50A510 P3FXZA Plasma Cycling On/Off"

I just fixed a PN50A550 with that info.

[debaser]

Re: Samsung PN50A550S1F shutdown

I found that thread last night as well. I'm going to pick up one of those tantalum caps and see if that fixes it. Thanks.

Can someone tell me how to get a test pattern going on this set? Do all the cables need to be plugged in for it to do this (specifically the main board)? And what pins exactly am I connecting to do this (Vs on to 5.3v)? Info I've found on this isn't clear to me.

[debaser]

Re: Samsung PN50A550S1F shutdown

Can someone tell me how to get a test pattern going on this set? Do all the cables need to be plugged in for it to do this (specifically the main board)? And what pins exactly am I connecting to do this (Vs on to 5.3v)? Info I've found on this isn't clear to me.

Can anyone chime in on this? I would like to try getting a test pattern on my TV to see for sure if it's the main board that is having issues. Thanks.