Panasonic TH-42PX80U Plasma stuck on a blank screen

[SurrealMustard]

That's right, it's another plasma to troubleshoot . This one powers up and the screen "lights up", but nothing ever appears on it. No menus, nothing. I can't tell if sound is happening or not because I don't know what input it's on or how the input selection menus are laid out.

When attempting to power it off, it takes close to ten seconds before the screen actually powers off. I don't know if it's supposed to work like that or not, but that is what it does.

The first thing the service guide says to check for is the green light on the "SC" and "SS" boards (the boards that are where the Y sustain and Z sustain would be in most plasmas), and they both power on. If the lights turn on, the flowchart says that the next suspect area is the mainboard ("A board"). Is that a sound diagnosis?

[HenryJ]

Re: Panasonic TH-42PX80U Plasma stuck on a blank screen

With all that nicotine on everything I would recommend cleaning all ribbon cables with 100% alcohol first, After can of air on all boards.

[johnboy1313]

Re: Panasonic TH-42PX80U Plasma stuck on a blank screen

https://www.badcaps.net/forum/showthread.php?t=42469

[SurrealMustard]

New board; worse luck

After reading a couple other threads and following the Panasonic troubleshooting strategy, I did end up replacing the mainboard. Unfortunately, while it was powering up and just not putting anything on the screen before, the new board invokes a seven blinks error code, which the service guide claims indicates a "Driver SOS 2 (SC floating voltage area)"; whatever that means. The panel is not coming on at all with this one, as far as I can tell. The service guide blames the either the SU, SD, or SC board for the seven blinks error, so that's a pretty wide scope.

I have one theory as to why there might be issues, but I want to run it by the community first: When hooking up the new board, I found that there was a missing connector in one of the places where there should have been one, which prevented me from hooking up one of the sets of wires leading to the front panel (or possibly one of the sides; pictured). Does anybody remember if that connector is important? If so, what can be done on mainboards that aren't equipped with the connection? Should I try to exchange the board?

[tvtimmy]

Re: Panasonic TH-42PX80U Plasma stuck on a blank screen

I got a 50" version of yours and had the same problem. It would turn on and panel would prime and glow a bit but no responce from remote. Power button would turn it off, but it would turn itself on by itself. I found a mainboard for it in one of my junk boxes and it was missing that connector also. It just goes to the front, under the flip up for the buttons and is for the front HDMI and the SD card and the R.W.& yellow AV hook up. Mine works though.
Also found a spare sc board with both buffers and a ss board in the boxes!!!
I will swap out all the spares at the same time to test them.

[Alastair E]

Re: Panasonic TH-42PX80U Plasma stuck on a blank screen

Refit original Main, Confirm its back to no-picture condition Check and clean carefully the ribbon-connections to the main/SS and SC....

If not, Looks like summit has failed--probably on the SC

[johnboy1313]

Re: Panasonic TH-42PX80U Plasma stuck on a blank screen

Did you look at the link I supplied?

[SurrealMustard]

tried original; no good

Refit original Main, Confirm its back to no-picture condition Check and clean carefully the ribbon-connections to the main/SS and SC....

If not, Looks like summit has failed--probably on the SC

Put the original back in and it's back to at least powering up now, but with nothing on the screen (same as before). Would it be advisable to try to return the new mainboard?

Did you look at the link I supplied?

Yeah. They concluded a bad component on the mainboard if I remember correctly. Probably the same deal as what's going on here.