Panasonic TX-P42GT20B - Stuck Stby

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

Still gives 10 blinks with SC removed

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

Still gives 10 blinks with SC removed

Ok ,

Well we better not jump to any conclusions then.

Can we get an image of the back or a list of boards? Is there a D board?

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

Yes it has a D Board - TNPA5299

[tn245]

Re: Panasonic TX-P42GT20B - Stuck Stby

Watching with interest. I've got the same A board doing 10 blinks even while SC and/or D board disconnected from it. I may follow along on mine with troubleshooting if nobody minds.

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

Watching with interest. I've got the same A board doing 10 blinks even while SC and/or D board disconnected from it. I may follow along on mine with troubleshooting if nobody minds.

well I'm getting rusty and lazy. Just spent all day trying to get a damn broken glow plug out of an i30.

Being a 3D model, it's not one I'm exactly ace on either. 10 blink SC board pops to mind but not if it's doing it isolated. Pretty sure there's a test you can do isolating the A board, TV turns on with either a dim screen or white screen.

If you can get it to do that Then A board would be high on th elist.

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.

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

Maybe digest this if you have not.

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

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.

Tried above steps, no led on SC or SS, with p6 and p7 disconnected, no white screen with p6 p7 and d5 disconnected.
The only way I can get led on SS to stay lit is to disconnect sc2.
Does this suggest power board

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

Tried above steps, no led on SC or SS, with p6 and p7 disconnected, no white screen with p6 p7 and d5 disconnected.
The only way I can get led on SS to stay lit is to disconnect sc2.
Does this suggest power board

Would suggest SC2 is shorted but why 10 blinks? did you disconnect SC20 ribbon and SC2 power?

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

Have not seen led on SC light up at all.

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

Have not seen led on SC light up at all.

yeah that's great. what do you get for error blink with sc20 and sc2 disconnected.?

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

Same can't seem to get off 10 blinks

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

Same can't seem to get off 10 blinks

doing my head in. you may have a double fault, does happen and I have had a bad SC damage the A board to have 10 blinks but the D is in between both.

If this was the regular 2D I 'd be more sure. Try that 10 blink steps with the multimeter and let us know.
Unfortunately I'll be getting some ZZZZZZs shortly, been a big day.

[tn245]

Re: Panasonic TX-P42GT20B - Stuck Stby

In my case I know the P and SC boards are good because I have had them running in another set. Also with D5/A31 disconnected it is turning on with full white screen. As soon as D5/A31 reconnected I get 10 blinks.

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

is that with just D5/A31 disconnected?

[tn245]

Re: Panasonic TX-P42GT20B - Stuck Stby

Yes, everything else connected as usual, but D5/A31 disconnected I'm getting white screen and leds on sc+ss lit. Odd because I'm sure I was getting the 10 blinks previously with D board disconnected as I stated in my earlier post but this is the state of play now. Possibly at that point I had D board disconnected from P board too.

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

still giving me 10

[tn245]

Re: Panasonic TX-P42GT20B - Stuck Stby

In this thread 10 blinks on a VT20 turned out to be D board:
https://www.badcaps.net/forum/showthread.php?t=59032

I can confirm that with D board disconnected from P board I get 10 blinks. So assuming your sc board is ok I think D board looks likely, but do check sc carefully because it seems to commonly cause 10 blinks too.

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

In my case I know the P and SC boards are good because I have had them running in another set. Also with D5/A31 disconnected it is turning on with full white screen. As soon as D5/A31 reconnected I get 10 blinks.

Sounds like it's going to be on the A - board. How close are you guys to each other?

[tn245]

Re: Panasonic TX-P42GT20B - Stuck Stby

Sounds like it's going to be on the A - board. How close are you guys to each other?

Not very, sadly.

So with D5/A31 disconnected I've got my S_15V at the A board and that's when I get white screen and it stays on. With it connected S_15V never comes up. No S_15V must be what is triggering the 10 blinks SOS.

[tn245]

Re: Panasonic TX-P42GT20B - Stuck Stby

I'm going round in circles a bit. 10 blinks is sub5V, sub3.3V, sub9V, F15V, Tuner Power, MIHO 3.3V, LED 8V, FRC 3.3V.

Out of that list the only one I find missing when I get the 10 blinks is MIHO 3.3V. (though it is there when D5/A31 disconnected)

MIHO 3.3V is derived on the A board from S_15V from the P board. S_15V looks to be turned on when the P board gets the Panel_Main_On signal which comes from the D board. The D board seems to send that signal by default when disconnected from A board, but A board (I think) tells D board whether to send this signal via PANEL_STBY_ON through D5/A31.

So it looks like my A board is not giving the signal to the D board to turn the panel on, and is then giving a 10 blink SOS when it doesn't sense MIHO 3.3V.