Panasonic TH-50PX80U Plasma - Powers on, no picture (Lightning?)

[fuxxy]

Just picked up this Panasonic TH-50PX80U from a friend. She says a lightning storm took out her TV, her laptop, and her Comcast STB.

Unit powers on, and the panel lights, but no video output. No buttons are responsive, even Power. After 5-10 minutes, the TV restarts. While the TV is on, I'm provided a steady red LED on the front of the TV, and a steady green LED on the "Scan Drive" and "Sustain Drive" boards.

I've pulled both the PSU board and the main logic boards - no signs of any physical damage and no odd smells.

Only two voltages are identified on the panel sticker, Ve (130V), and Vsus (185V)
I've tested these voltages - test points were all on the SCAN and SUSTAIN boards:
Ve: 129.0V
Vsus: 184.1V
VSET: 319V
VAD: 147.8V

Without anything else to go on, I'm thinking the logic board is toast - My next test is plugging in sources and see if I get audio.

**EDIT**
This flowchart in the service manual pretty much says the "A Board" (Which is the logic board) is suspect. Now to diagnose!

[freakaftr8]

Re: Panasonic TH-50PX80U Plasma - Powers on, no picture (Lightning?)

If you are getting a screen lit but no video and buttons unresponsive I would be more inclined to say mainboard issue..

[erskine]

Re: Panasonic TH-50PX80U Plasma - Powers on, no picture (Lightning?)

hi I'm new here. are you getting any error codes from the led. if so how many blinks ?

[fuxxy]

Re: Panasonic TH-50PX80U Plasma - Powers on, no picture (Lightning?)

@freakaftr8: The "A" Board is the one I suspect - with the HDMI and component connections. Did i use the wrong terminology?

@erskine: No error codes from LED. Solid red light - which I interpret as normal.

[freakaftr8]

Re: Panasonic TH-50PX80U Plasma - Powers on, no picture (Lightning?)

Yes mainboard. Logic board is the one that has ribbons going to the panel. That board should be ok

[fuxxy]

Re: Panasonic TH-50PX80U Plasma - Powers on, no picture (Lightning?)

The mainboard is the one I was referring to, I apologize!

it seems that all the sources for this board (TNPH0716 "AH" suffix) are out of stock..

Is there some sort of repair process for these boards? I don't see any physical damage.

[fuxxy]

Re: Panasonic TH-50PX80U Plasma - Powers on, no picture (Lightning?)

On a whim, I disabled the "Audio/Video SW" (IC3001) by removing the inductors connecting VCC+9V and VCC+5V to their respective power sources. No change.

[fuxxy]

Re: Panasonic TH-50PX80U Plasma - Powers on, no picture (Lightning?)

I realized I never checked to make sure all voltages were present on main board before I started disabling things. Test points are mostly on solder side.
However, upon removing the board from the chassis (and still plugged in) I get a 6 blink error. I wonder if ground is not supplied elsewhere? An error code means SOMETHING is working on the mainboard, correct?
I was thinking the boot ROM was corrupted.