panasonic TH-50PX80U no picture

[TimT]

working on a panasonic TH-50PX80U it will power on and the screen is dim it changes from black to a shade of gray. other then that no picture at all.

I tested 2 fuses (see picture) one was at 16.4 on both ends the other is 0.10 on both ends. the sustain boards have green leds.. the are on." green " unplugging either sustain boards power causes the Tv not to turn on..

the TV will turn on with the power light is red.. but if I turn it off with the power button it turns off but in about 4 seconds turns off again. so i have to unplug the tv to turn it off.. and suggestions?

[TimT]

Re: panasonic TH-50PX80U no picture

I did notice unplugging a cable from z-sustain will cause one side of screen to display " blue rain " no sign of a picture! just static

[drpj23]

Re: panasonic TH-50PX80U no picture

You probably have a Z-sustain fault due to the dim picture.
And ya Panasonics are touchy when removing boards.

If you are referring to those 2 fuses in the second picture, if those were bad your set would fail to have power. Little confused though how you tested them.

[TimT]

Re: panasonic TH-50PX80U no picture

I can get the screen full bright by ajustment.. just nothing on screen no menu ect.. I tested some voltage regulators all the information is in the pictures thanks. from both y-z sustain

[DavidOH]

Re: panasonic TH-50PX80U no picture

That sounds like a main board problem. Here's the manuals if you don't have them.


http://www.scribd.com/doc/61383733/TH-50PX80U

http://www.scribd.com/doc/24963802/1...Plasma-Display

[TimT]

Re: panasonic TH-50PX80U no picture

forgot to upload the pictures...

[TimT]

Re: panasonic TH-50PX80U no picture

I noticed on the main board the is a little red led under a flap. im thinking this it because of a issue on the board? I also noticed what looks like a bad capacitor?

[drpj23]

Re: panasonic TH-50PX80U no picture

Ok, I misread and thought you had a picture
Ok, I would go with DavidOH with the main being a culprit or even the CTRL (D) board.

The red light is for the optical out and is normal.
That cap looks to be good too - its paint may just look weird and the tri-wing shape is the stamped vent hole.

I can get the screen full bright by ajustment.. just nothing on screen no menu ect

How exactly did you do that?

[DavidOH]

Re: panasonic TH-50PX80U no picture

Don't know about the cap. The flap with the red light is the digital audio out. It uses a fiber opitic cable.

[Cosmo66]

Re: panasonic TH-50PX80U no picture

Are there any small smd fuses on the main board? Usually there's at least 1.

[TimT]

Re: panasonic TH-50PX80U no picture

there is a ajustment on the power board that will turn the screen to Fulbright. I'm not looking at the board now so I can't tell you what it is. but I have ajusted it back down. I did not notice any surface mount fuses. but I will post more pictures of the mainboard when I get off today. I'm thinking it's the mainboard to. both the sustains has a green LED lit on it. I am assuming that that means there okay?
but the screen seems fine just no information going to it. thanks everyone for your help

[randtek]

Re: panasonic TH-50PX80U no picture

It is not wise to adjust potentiometers in a plasma set if you don't know what you are adjusting. Some of those adjustments are pretty critical, and they rarely shift, so adjusting them just tends to mask the original problem, or introduce others

[TimT]

Re: panasonic TH-50PX80U no picture

you're probably right! I just love to tinker hopefully that won't get in trouble one day :-) no smf on front side could they possibly put one on the back side? I haven't removed the board yet

[tom66]

Re: panasonic TH-50PX80U no picture

You probably adjusted Va and hopefully panel address drivers were OK with receiving >65V, which is the typical rating for them. Otherwise, you kill the panel.

When you disconnect the power to the address buffers on the bottom of the screen weird stuff happens, blue rain could be one possible symptom. If you still get blue rain the panel's probably still OK.

[drpj23]

Re: panasonic TH-50PX80U no picture

Green LEDs are indeed an indication of an OK board.
I realize that this looks to have an integrated D board so A board is really the only option. But just for kicks, just check those ribbons coming from the main.

Panasonics also are funny about not having any fuses (except on P/S) but I suppose that is they are confident in their voltage detection circuits to mostly do the job (and there are a bit more fuses on those power supplies than most).

[tom66]

Re: panasonic TH-50PX80U no picture

It seems when the sustains on most TVs fail is on first power up (i.e. from cold), so the fuses are of no use -- PSU immediately enters current limit.

[TimT]

Re: panasonic TH-50PX80U no picture

I still get the " blue rain " don't seem to be any fuses at all on the mainboard. I have pulled the mainboard I will reinstall it making sure all the cables are connected well.

[TimT]

Re: panasonic TH-50PX80U no picture

strange I pulled the mainboard to take some pictures. I reinstalled it and make sure all the connections were good. now when I turn it on I hear the power click in and see the two sustain LEDs light up. and then I hear another click and the power shuts down. then the power LED on front
blinks 7 times in a repeating pattern?

[joeu1970]

Re: panasonic TH-50PX80U no picture

Watching my TH-50PX80U and it lost all power without any warning. Unable to turn on set at all. Any suggestions?

[cashkennedy]

Re: panasonic TH-50PX80U no picture

Your problem is not in anyway similar to the original posters problem other then the same model, so you probably should have started a new thread.

If your set doesn't even light up the standby LED then you would need to take voltage readings of the power supply board using a multimeter. If you don't know where to begin with testing the power supply you might want to take the back of the set off and post a picture of the power supply board. Most of the outputs on a power supply board are clearly printed next to the connectors that leave the board. https://www.badcaps.net/forum/showthread.php?t=25810 explains some basics of testing a tv / and the power supply