Samsung PN51D530A3F plasma with weird pixelated display

[farmtech]

Hello, I am having quite a time getting this PN51D530 back to life. The set would not power on, was flashing the LED a few times and would try the power supply relay for a few seconds but then turn off. I replaced several shorted FETs on the Y and Z boards and a shorted rectifier. Then the power supply decided to quit and only had 3.2V on the PS standby line instead of 5.2V. After replacing the power supply board the set powers on but the screen shows strange pixel patterns. When the set is first turned on several pixels are out but the longer the set is on the more pixels come back to life. The colors are off as well. It appears to me that the pixels are not "driven" hard enough but I dont know. In the no signal picture note the missing pixels, the bar should be completely blue with no missing pixels. That pic was taken when the set was turned on, if left for several minutes most of the pixels would come back. Any thoughts or ideas would be greatly appreciated.

Thanks much!

[tom66]

Re: Samsung PN51D530A3F plasma with weird pixelated display

Looks like Ve or Vs voltage might be low, have you checked these?

[farmtech]

Re: Samsung PN51D530A3F plasma with weird pixelated display

I checked the 4 voltages (VS, VE, VA, VSC) on the sticker on the glass and they were all within 1V. Everything seems okay as far as I can tell. Any other ideas?

[tom66]

Re: Samsung PN51D530A3F plasma with weird pixelated display

Try increasing Ve and Vs.
Ve increase by max 15V, Vs by max 7V.

[farmtech]

Re: Samsung PN51D530A3F plasma with weird pixelated display

Hi Tom, I was only able to adjust Ve from 80 to a max of 88 and it did not have any effect. I did get slight improvement when adjusting Vs though. I could take it from 207 to 214. The improvement was slight and it is still not what I consider acceptable. I wonder if I still have problems with the Y board.

[tom66]

Re: Samsung PN51D530A3F plasma with weird pixelated display

Is the -Vsc measuring OK?
You have applied latest Samsung firmware?
Do you own an oscilloscope to make waveform tests?

[farmtech]

Re: Samsung PN51D530A3F plasma with weird pixelated display

VSC measures good, I have not tried updating firmware. I can attempt that but TV was working fine until it would not turn on. I did replace 5 FETs and a rectifier on the Y and Z boards. It seems to have had some sort of electrical event to hurt that many parts at one time.

I do have a scope if there is anything I can check. Thanks for the help so far.

[tom66]

Re: Samsung PN51D530A3F plasma with weird pixelated display

OK, post a picture of your scope. Is it rated minimum 300V or higher? Do you have a 10X probe available?

[farmtech]

Re: Samsung PN51D530A3F plasma with weird pixelated display

I've attached a pic of my scope, Tektronix TPS2024 it is 300V and I do have 10X probes.