50PF9830a/37 Philips Plasma Clay Face? Posterizing?

[ghiotom]

I'm not sure of the proper terminology for this problem, but if you zoom in on the picture you will notice purple dots, banding, and pastel looking faces. Sometimes the screen will flicker and the picture will go back to normal. I've tried a heat gun, freeze spray, and prodding of boards to get it back to normal. I have unseated and seated every connector in the tv. My gut tells me logic board, but if someone has some ideas let me know.

[tom66]

Re: 50PF9830a/37 Philips Plasma Clay Face? Posterizing?

This is called maldischarge or underdiffusion.

Either the Vs is low, the Vset is wrong, the Vscan is wrong or the Yrr/Yfr are set incorrectly.

It is most likely not a control board problem.

[ghiotom]

Re: 50PF9830a/37 Philips Plasma Clay Face? Posterizing?

Thanks Tom. The voltages are spot on with the values on the sticker. I can vary the number of dots by changing Yrr/Yfr, but it has no effect on the pastel effects. Like I said, sometimes it will just flicker and then start working perfectly out of the blue. As long as it doesn't appear to be the display, I might start swapping boards and the logic board is the cheapest.

[tom66]

Re: 50PF9830a/37 Philips Plasma Clay Face? Posterizing?

Sometimes I just alter the voltages to personal preference. The panel performance can drift with the older plasma panels.