Panasonic P50GT30 won't turn on?

[Baked Potato]

Hi, I have a 2011 Panasonic P50GT30 plasma. A week ago I went to turn it on and it won't respond to anything. I've read a lot of other posts saying flashing lights will tell you what's wrong, but no lights come on at all. It sounds like it is some sort of power or main board problem (not SC, SD, or SU boards?) but I don't know how to verify that and what to do if it is. I appreciate any help.

I'm attaching a picture of the boards. I have detailed photos of all the boards if needed.

Thanks!

[tw2005]

Re: Panasonic P50GT30 won't turn on?

I had a 50GT30A dead, no standby voltage a while back. On the underside of the main P board, q101, a tiny SMD FET had failed

[tom66]

Re: Panasonic P50GT30 won't turn on?

Follow pg 25 and let us know how you get on from there:

[tw2005]

Re: Panasonic P50GT30 won't turn on?

Ignore the green LED bit, pretty sure US market is red only. We have red standby, red blinks error, green blinking on startup and solid green when running.

[Baked Potato]

Re: Panasonic P50GT30 won't turn on?

Thanks. I had a look at this and went through the flowchart. It says to first test the SS board (4pin (P15V)), then the SC board (TP82 (P15V)), and then the A board (13 pin (P15V)).

I think I've identified the right sockets to test (they all go back to the P board). I've identified them on the attached photos. Do I have the right ones?

Also attaching detailed shots of the three boards (SS, SC, A).

[syaoran123]

Re: Panasonic P50GT30 won't turn on?

Have you tested the fuses (i think there's 2 of them) on the P board? A failed SC can take out the mosfets on the P board and thus blowing the fuses on the P board and giving no power.

[Baked Potato]

Re: Panasonic P50GT30 won't turn on?

I'm a total newbie doing anything like this so it's taking me a bit. I tested all of the fuses on both the P and P2 power supply boards. Used a multimeter on the diode setting and it beeped for each of them. As I understand it, that indicates they are good (not open). Also, I don't know that I can remove them, but I tested them while in the boards, which I believe is fine?

I also tested the power coming into P2 and then going from P2 to P and it was 120v for both.

Following the guide from tom66, it says to "Disconnect SS11. Does SS11's 4pin (P15V) short to GND?" I found SS11 and disconnected it but I'm not entirely sure what this means to do. Attached is the schematic and a picture of it on the board.

A few questions regarding these directions:
1) I'm assuming I should have the TV plugged in for this test?
2) If everything is working, I'll get a readout of 15v (that's what the P15V means?)
3) I'll place the black end of the multimeter on the metal backing that the boards are screwed into and then the red part on what? The pins for the connector on the SS board? Or the pins on the inside of the cable that I unplugged from SS11?
4) "Short to GND" would be getting a 15v reading? That indicates power is getting to the SS board but the SS board isn't working?
5) Edit: There's also a little label on the board next to a solder point that says "P15V". Is that of any meaning to me?

Sorry for such basic answers. Have a lot to learn. Appreciate all the help!

[syaoran123]

Re: Panasonic P50GT30 won't turn on?

That is right, for normal working fuses you should hear a beeping sound in diode mode. The power supply seems fine then and it is likely the mainboard at fault. Mainboard stores the fault codes and it is not giving any codes because that's the culprit.

[tw2005]

Re: Panasonic P50GT30 won't turn on?

That is right, for normal working fuses you should hear a beeping sound in diode mode. The power supply seems fine then and it is likely the mainboard at fault. Mainboard stores the fault codes and it is not giving any codes because that's the culprit.

How did you reach this conclusion? So far from what i read he's confirmed 120VAC is present at the input of the P2 board which is where it is routed from the filter and power cord, then jumps to the P board, also 120Vac present.

There's no codes because it's dead, no lit LED present.

May be A-board, shorted SC or bad P board , at a guess.

[tw2005]

Re: Panasonic P50GT30 won't turn on?

I'm a total newbie doing anything like this so it's taking me a bit. I tested all of the fuses on both the P and P2 power supply boards. Used a multimeter on the diode setting and it beeped for each of them. As I understand it, that indicates they are good (not open). Also, I don't know that I can remove them, but I tested them while in the boards, which I believe is fine?

I also tested the power coming into P2 and then going from P2 to P and it was 120v for both.

Following the guide from tom66, it says to "Disconnect SS11. Does SS11's 4pin (P15V) short to GND?" I found SS11 and disconnected it but I'm not entirely sure what this means to do. Attached is the schematic and a picture of it on the board.

A few questions regarding these directions:
1) I'm assuming I should have the TV plugged in for this test? No
2) If everything is working, I'll get a readout of 15v (that's what the P15V means?)maybe but TV wouuld have to be on and working so forget that thought for now
3) I'll place the black end of the multimeter on the metal backing that the boards are screwed into and then the red part on what? The pins for the connector on the SS board? Or the pins on the inside of the cable that I unplugged from SS11?pin 4 and gnd. you are checkking to see if it's shorted at the board
4) "Short to GND" would be getting a 15v reading? That indicates power is getting to the SS board but the SS board isn't working?If there was a short to gnd on the board, yes that indicates a board issue.

5) Edit: There's also a little label on the board next to a solder point that says "P15V". Is that of any meaning to me? A P15V test point ( 15volt supply) you could probe that to gnd for short.

Sorry for such basic answers. Have a lot to learn. Appreciate all the help!

.

[syaoran123]

Re: Panasonic P50GT30 won't turn on?

How did you reach this conclusion? So far from what i read he's confirmed 120VAC is present at the input of the P2 board which is where it is routed from the filter and power cord, then jumps to the P board, also 120Vac present.

There's no codes because it's dead, no lit LED present.

May be A-board, shorted SC or bad P board , at a guess.

The PSU on late model panasonic plasma rarely fail and if they do, the fuse blows together with the power mosfets. He tested the PSU and he said the fuses were OK. Therefore the only other possibility is the mainboard, which panasonic calls the A-board.

From experience, I have fixed a panasonic LED tv which had no fault code present. You guessed it, the problem was the mainboard and psu was good.

[R_J]

Re: Panasonic P50GT30 won't turn on?

I would check P25 pin 5 on the power supply for stby+5, if there is no standby voltage then start looking at the power supply board
If there is stby I would disconnect ss & sc plugs, and if there still is no blinking led I would start to suspect the A (main) board.

I just repaired one of these TC-P50GT30's but it had a 7 blink and it had 6 shorted transistors on the sc board.

[tw2005]

Re: Panasonic P50GT30 won't turn on?

The PSU on late model panasonic plasma rarely fail and if they do, the fuse blows together with the power mosfets. He tested the PSU and he said the fuses were OK. Therefore the only other possibility is the mainboard, which panasonic calls the A-board.

From experience, I have fixed a panasonic LED tv which had no fault code present. You guessed it, the problem was the mainboard and psu was good.

That's a very big generic assumption. The board can fail with no fuses blown and present dead TV. If Q101 fails on the P board, it will be dead, no standby .

[tom66]

Re: Panasonic P50GT30 won't turn on?

That's a very big generic assumption. The board can fail with no fuses blown and present dead TV. If Q101 fails on the P board, it will be dead, no standby .

Also on some Panasonic TVs the LED can be dead but there can be other causes, SC/SS board on plasmas and dead LED array/driver board on the LED backlit sets. Happens a lot and people mistakenly replace the main board but it's another fault.

[JasonMK]

Re: Panasonic P50GT30 won't turn on?

Was Baked Potato ever able to get his problem resolved?