Panasonic TC-P50U50 Plasma Not Powering Up

[SurrealMustard]

I'm working on this Panasonic Plasma and it's got me stumped. It seems to be exhibiting no signs of life. Pressing the power key yields no response - no clicks, no lights, no sounds of any kind. Measuring at the main connector from the power supply, all I have is 4.4v on the 5v standby line. Everywhere else is dead. Any tips for where to go from here?

[martino]

Re: Panasonic TC-P50U50 Plasma Not Powering Up

disconnect the little ribbon cable from mainboard to ss board,does 5 volt recover?
If not,disconnect mainboard from power supply,does 5 volt recover?

[SurrealMustard]

Still just 4.4!

disconnect the little ribbon cable from mainboard to ss board,does 5 volt recover?
If not,disconnect mainboard from power supply,does 5 volt recover?

Negatory. STBY5V holds steady at 4.4 either way.

[Moreno83]

Re: Panasonic TC-P50U50 Plasma Not Powering Up

4.4V is "normal". What meter are you using? My fluke meter sometimes measures 4.48v.

If you only got 5v on the power supply going to the mainboard and nothing happens then your mainboard is dead. Replace it and the tv will turn on. ( Unless other boards have failed. )

Any history on the tv? Powersurge?

[martino]

Re: Panasonic TC-P50U50 Plasma Not Powering Up

These models are notorious for loose screws on the ss board,causing them to blow a fet.
It will be the top screw that causes it,take it out and see if you see signs of spark marks on the pcb where that screw sits.
The fet that blows is the top component on the highest heat sink(closest to the top),Q051 if I remember correctly,it will short circuit between all 3 legs,maybe check that?

[Moreno83]

Re: Panasonic TC-P50U50 Plasma Not Powering Up

Yes Martino but that wont result in a completely dead tv. It would give a blink code.

[SurrealMustard]

fixed!

Good call. Mainboard was indeed the culprit.