Top part of screen greyed out

[tech2014]

I have a panasonic vierra 42" plasma tv that has the top half of the screen greyed out. Any ideas?

[tom66]

Re: Top part of screen greyed out

Can you supply a picture of the fault? It is hard to tell what you mean by "greyed out"...

[tech2014]

Re: Top part of screen greyed out

Here are the pictures of the tv.









The left side board is the Y SUS board I took out of the tv

[tom66]

Re: Top part of screen greyed out

Probably Y-buffer fault. (SU or SD)
Can you see Vscn test point on SC (Y-sustain) board?
Please check the voltage and see what it is measuring. It should measure 120V to 150V wrt to -Vad (usually it is measured across a resistor.)

[tech2014]

Re: Top part of screen greyed out

I can smell something hot on the Y SUS board. The tv eventually shuts down after a few minutes on. I will get the voltages for you soon.

[tech2014]

Re: Top part of screen greyed out

I found another board, any idea what this does?

[tech2014]

Re: Top part of screen greyed out

I found a load resistor damaged and looks like it has a burn mark on it. It also gets extremely hot and is the burning smell is from this part. Problem on Y SUS board or the SU board.

It is on the left side board (Y-SUS)

[tech2014]

Re: Top part of screen greyed out

I get only 40 volts on Vscn. My Ve, VSUS are both good.

[tech2014]

Re: Top part of screen greyed out

I FIXED THIS TV. It was an open circuit 0 ohm SMT resistor on the SU board. Fixed and tv now working YAY!!!!!!!!!!!

[mmartell]

Re: Top part of screen greyed out

Nice job. How did you find the shorted component ?

[tech2014]

Re: Top part of screen greyed out

Nothing shorted but the 0 ohm resistor measured OL in and out of circuit. This service manual for this tv actually had all the schematics which helped immensely.

[tom66]

Re: Top part of screen greyed out

Nice fix! Could you show us exactly what resistor for future reference? Or the component # on the schematic?
Yes, I do like that Panasonic provides full service guides for their plasmas - something for other manufacturers to look at doing. (I wish.)