Panasonic TX-P42GT20E 3D , does not turn on!

[Moreno83]

Hey guys ,

Got this tv , it does not turn on after lightning struck the house. ( completely dead ).
I had a spare power supply and replaced it but still the same , then i took a spare main board from a different set ( same series , not 3D ).
Set turned on with original power supply but i got a white screen. ( LVDS cable not connected due to size ).

So i took the original main board and did not connect the "lvds" cable and the set turns again on with a white screen.
When i connect the LVDS cable , the set does not turn on.

So its either the main board OR the small board in the middle?
The original main board had a blow IC next to the USB input.
Pictures coming in a few minutes.

What do you guys think?

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Here are the pictures! The screen looks like it has stripes , thats because of the camera! Screen is white.

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

The LVDS cable I'm talking about is the white cable going from the main board to the control board in the middle.
When i turn the tv on with the cable connected the set stays off. When i flip the black lock on the cable the set turns on with a white screen , hope this helps.

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Im suspecting its the A board? But I'm curious how lighting blew the A board ( small board ).
I would suspect the main board OR power supply…….

Any suggestions?

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

So i also replaced the SC board , issue is still the same.
The spare parts are from the TX-P42V20E , all boards are the same but i don't know if the P42V20E also has a control board/A board , i couldn't find it between my spare boards……

I could try to replace the SS board also , but i don't think thats the problem.

Anyone?

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

I downloaded the service manual from the TC-P42GT30A , it has the same main board as the P42V20E.

So the visual difference between these tv's its that GT20E has a control board. Could i use the GT30A main board in THIS tv? The GT30A/V20E have the same layout in lvds cables going to the SC board/panel…….

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Ok , i removed the A board and replaced the main board with the main board from the V20E.
Installed it using different lvds cables and set turns on and i get a picture! It then turns off and blinks 11 times….

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Nobody got any suggestions?

[tw2005]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

changing so much stuff randomly makes it hard to follow what you're thinking.

If it does not turn on, dead, no LED, no clicks of the relay, I'm thinking A board. The small board you talk about is the D board and unique to the 3D models.

Without looking the VT20E has fans hence the 11 blinks shutdown since this has no fans and the board is looking for a return signal indicating the fans are spinning.

The burnt blown IC is probably a good clue, a clear focussed picture of that may be handy. good chance whatever it is is shorting the board, may even be possible to remove it and clear the short for the board to work again. A long shot but it's dead anyway, nothing to lose.

[tw2005]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Just so there's no confusion, this is the board layout

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Thx TW2005 for the reply! Im sorry , english is not my first language so i probably make some mistakes!

So i'll try to explain what i've done.

When i turn on the TX-P42GT20E with all original parts the set does NOT turn on , completely dead.
When i remove the white lvds cable from A board to D board the set turns on , the relay clicks and i get a white screen. ( even with the small IC thats blown ).

I then used a working mainboard from the VT20E , its almost the same except the connections for the LVDS ( Because of the D board ).
I turned the tv on with lvds cable removed and again i get a white screen. This makes me think the original A board is still ok?

So i wanted to know if the rest of the parts were ok so instead of fixing the TX-P42GT20E i modified the tv using all parts from the VT20E. You might ask , why?
ALL PARTS of the tv are exactly the same as the TX-P42GT20E.
So what happens is that the tv is working fine except the 11 blinks due to the fans missing ( I wasnt sure it had fans , but i knew 11 blinks was fan problem).

So now im wondering , does the TX-P42GT20E need a new D board? The only time it doesnt work is when the D board is connected.......

Hope its more clear for you now

[tw2005]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Thx TW2005 for the reply! Im sorry , english is not my first language so i probably make some mistakes!

So i'll try to explain what i've done.

When i turn on the TX-P42GT20E with all original parts the set does NOT turn on , completely dead.
When i remove the white lvds cable from A board to D board the set turns on , the relay clicks and i get a white screen. ( even with the small IC thats blown ).

I then used a working mainboard from the VT20E , its almost the same except the connections for the LVDS ( Because of the D board ).
I turned the tv on with lvds cable removed and again i get a white screen. This makes me think the original A board is still ok?

So i wanted to know if the rest of the parts were ok so instead of fixing the TX-P42GT20E i modified the tv using all parts from the VT20E. You might ask , why?
ALL PARTS of the tv are exactly the same as the TX-P42GT20E.
So what happens is that the tv is working fine except the 11 blinks due to the fans missing ( I wasnt sure it had fans , but i knew 11 blinks was fan problem).

So now im wondering , does the TX-P42GT20E need a new D board? The only time it doesnt work is when the D board is connected.......

Hope its more clear for you now

No, I'm thinking A-board, that's where the blown IC is , yes? the D board controls the panel so my line of thinking is because you've isolated it from the A board then it automatically is turning the panel on.

A board is dead.

there is a 3D training guide although for the 50" however principle of operation is the same. When the LVDS ribbon is removed the TV is meant to turn on, white screen.

So that confirms all else is good, it's not the D board that is faulty

Yes it's a strange one with the 42" having the same panel for 2D & 3D. definitely not the case with the larger panel. So it does make sense to convert to 2D if all you want is a Tv that works.

Would be interesting to fault find the original A board, any pictures of that burnt IC.

"Method To Turn On the Panel Drive Circuit Only (A Board is Isolated)
It's possible to have the “Panel Drive Section” running with the “Signal Processing Section” (A board)
disconnected.
By separating the 2 sections, it could be determined if the symptom on the TV is created by the A
board or one of the boards on the Panel Drive Section.
Note: Disconnecting D3/A32 and D5/A31 allows the TV to turn on by itself with a white screen after
it is plugged in to the AC line. This procedure does not disable the A board.
To completely disable the A board:
1. Unplug the TV.
2. Remove connectors P6 and P7 from the power supply. (See note on previous slide.)
3. Plug in the TV (Do not press the power button).
• The TV partially turns on by itself.
• The screen stays black.
• No fan operation.
• The LEDs on the SS board and SC board are on.
To force the TV to display a white screen:
1. Unplug the TV.
2. With P6 and P7 disconnected, disconnect D5 from the from the D/A board.
3. Plug in the TV.
4. Now the TV turns on by itself with a white screen."

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

thx for the reply. I already ordered the D board because i thought it had a short! ( Because when i connect it it doesnt work ).

Any way to find the fault on the A board? I'll make a picture of the burned IC but that component is not the problem.
I already tried to desolder the same part from the other mainboard to this board and issue is still the same. Tv works without that ic. IC says "D2508", its next to the USB port.

[tw2005]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

thx for the reply. I already ordered the D board because i thought it had a short! ( Because when i connect it it doesnt work ).

Any way to find the fault on the A board? I'll make a picture of the burned IC but that component is not the problem.
I already tried to desolder the same part from the other mainboard to this board and issue is still the same. Tv works without that ic. IC says "D2508", its next to the USB port.

Ok so it's a diode. What do you mean it works without that part though? You said the TV will not work with that A board or are we talking about the board you have removed it from?

yes it probably would but on the blown board it's probably taken out something else and shorted .

[tw2005]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

I guess too late to cancel the purchase and you got the same revision board for 42"?

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Im talking about both boards.
At first i used the mainboard from the VT20E without the LVDS cable and it turns on.
Then i used the original mainboard from the GT and it also turned on without the LVDS cable and this board had a blown diode.
I removed the diode from the VT20E board and placed it on the GT board but fault is still the same.

[Neelix]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Is the blown part a IC or diode? Don't see a D5208 in the service manual?

[tw2005]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Im talking about both boards.
At first i used the mainboard from the VT20E without the LVDS cable and it turns on.
Then i used the original mainboard from the GT and it also turned on without the LVDS cable and this board had a blown diode.
I removed the diode from the VT20E board and placed it on the GT board but fault is still the same.

Ok, so all that proves is the TV will turn on with the LVDS lead disconnected and produce a white screen which is correct operation of the D board.

the A board is not turning the panel on when connected.

You'll confirm for sure once you have the replacement D board but I'm confident I'm right but either way if it fixes it then great , I don't have a problem being wrong and learning but that's my gut feeling with this one.

I'll upload the 3 d manual for you as it describes the operation at turn on.

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Not sure if its a diode or ic , it does have that part number on it. Its viscible on the mainboard picture , in the upper right corner.

[Moreno83]

Re: Panasonic TX-P42GT20E 3D , does not turn on!

Im also thinking your right TW2005 , im still learning!

Is it the cpu on the mainboard? But why does it turn on without the D board?
Or is it a short somewhere?