Panasonic TX-P42GT20B - Stuck Stby

[ScottyWhistle]

Re: Panasonic TX-P42GT20B - Stuck Stby

Well, I'm on the verge of giving in.

A new A board and a new P board, together, do not work. 10 binks. I have made sure every wire in connectors P6 and P7 work/have continuity. No other connectors are connected at all. No D board, no SC, no SS.

What does this mean? Have I been sent a defective A or P board? I don't see a way for me to find out unless I order yet another.

[ScottyWhistle]

Re: Panasonic TX-P42GT20B - Stuck Stby

Well, disaster struck. The replaced A board had the exact same issue. 10 blinks. I'm thinking it surely has to be the power board.

[tn245]

Re: Panasonic TX-P42GT20B - Stuck Stby

Yes, replace the A board. It's extremely unlikely to be P or SS.

[ScottyWhistle]

Re: Panasonic TX-P42GT20B - Stuck Stby

I've given it my best shot, according to the 2010 Viera training seminar PDF posted earlier in this thread, if the voltage between A6 pin 1 and 9 is 15v just before the TV shuts down, the problem is the A board.

My only worry is that although very similar, this PDF is for VT20T series TVs. Will this rule still apply? Shall I go for the A board replacement?

Thanks

[ScottyWhistle]

Re: Panasonic TX-P42GT20B - Stuck Stby

How can I rule out the P and SS board?

[tn245]

Re: Panasonic TX-P42GT20B - Stuck Stby

Most likely the A board is bad then.

[ScottyWhistle]

Re: Panasonic TX-P42GT20B - Stuck Stby

Hey,

Sorry to dig up this post but I've been following along with the same model, and I've had different results - and so hit a brick wall.

I tested voltages across P11 pins 1/4 and P2 pin 1 with the SC connected/disconnected, and got these results:

SC Disconnected
P11 pin 4 = 15.6v
P11 pin 1 = 208v
P2 pin 1 = 209v

SC Connected
P11 pin 4 = 16v
P11 pin 1 = 208v
P2 pin 1 = 208v

Also, no continuity between the Q661 legs.

I believe this rules out the SC board?

I get 10 blinks with the SC both connected and disconnected
I get 10 blinks with the D board (D25 connector) connected and disconnected

I have visually checked every port on the A board for damage or bent pins and I have not found anything.

I'm stuck, I'm a beginner at this so I can't work out what to test next, any guidance is extremely appreciated.

The only extra info I've found is that there is no voltage across P2 or P11 when D25 is disconnected, but from what I've found this is normal.

Also by some crazy coincidence live in the same town as benjamin - feel free to come and fix it if you're a pro these days.

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

Maybe buffer board connections
https://www.youtube.com/watch?v=h4XWCxUsSVU

spot on, thank you all for your help

[vinceroger69]

Re: Panasonic TX-P42GT20B - Stuck Stby

Maybe buffer board connections
https://www.youtube.com/watch?v=h4XWCxUsSVU

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

Replacement SC board did the trick, now i have 3 horzontal lines on screen tried mirror in service mode but as they are in centre of screen they stay the same

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

i hooked it up (SC50 Bypass) no error flash, solid green light on tv.
led bright on SC and SS.
performed short test on sm board ribbon connectors - no short.

so if i now install the AW fully it'll fire up as it should do with AH installed?
i have got a copy of both of the manuals.

It should, just not matched to the panel but it'll work. I've thrown a 50" in a 54 panel for a quick test, then repaired the original board

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

i hooked it up (SC50 Bypass) no error flash, solid green light on tv.
led bright on SC and SS.
performed short test on sm board ribbon connectors - no short.

so if i now install the AW fully it'll fire up as it should do with AH installed?
i have got a copy of both of the manuals.

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

any ideas on how many/which ones would need swapping out?
and if its just coils and caps which i am capable of but anything involving micro surgery then i'd be at a loss!

Before you do this, I would check the buffers are ok, then hook it all up, fire the TV u check it is all good including 3D if you use it.;

Then get a copy of the manual for your model, a copy of the TX-P50G20B or E as that is the model which uses rev AW

Then visually look for differences or compare all C16xxx and L16xxx parts numbers and locations to determine what is the same, what is different.

If you have the boards laid out in front of you you'll start noticing the differences.

I'm not going to work it out for you. I've never done it but it's feasible or return the board and get the correct one

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

Fair dinkum 100% wrong board

you could try converting which would involve swapping out a bunch of capacitors and coils from your old board to the replacement.

any ideas on how many/which ones would need swapping out?
and if its just coils and caps which i am capable of but anything involving micro surgery then i'd be at a loss!

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

ok passed bypass test, how do i make sure sm didnt blow sc board to start with?

well, if you have a meter in diode and continuity beep, place one probe on SD/Su board gnd plates(bolt plates) and slide the other carefully along the contact pins on the output ribbon connectors watching for dead short.

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

ok passed bypass test, how do i make sure sm didnt blow sc board to start with?

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

make sure the SD/SU gnd bolts are not bolted to the SC as well if doing that bypass test.

[tw2005]

Re: Panasonic TX-P42GT20B - Stuck Stby

Well my replacement SC board arrived this morning..............
.......However, the board that i received is a "fully tested" TNPA5081 AW.
I assume that as one is for the 50" and the other for the 42" board needs returning?
good news is that Q661 is ok (wry smile)

Fair dinkum 100% wrong board.

TXNSC11NEK or TNPA5081AH

Since the same board is used in both the 2D and 3D models you may get away with it for a quick test and confirm that's all you need.

But, i would check the sd and su boards are not shorted or perform the 7 Blink SU/SD board isolation test where you fully install the sc bit don't connect the SD or SU, jumper the small 2 pin connector on the SC at SC50 (lower left )

If the TV now turns on and stays on with the green LED, then that would be good and turn the TV off,

Get the right board or you could try converting which would involve swapping out a bunch of capacitors and coils from your old board to the replacement.

[benjamin.d.bird]

Re: Panasonic TX-P42GT20B - Stuck Stby

Well my replacement SC board arrived this morning..............
.......However, the board that i received is a "fully tested" TNPA5081 AW.
I assume that as one is for the 50" and the other for the 42" board needs returning?
good news is that Q661 is ok (wry smile)

[tn245]

Re: Panasonic TX-P42GT20B - Stuck Stby

Before you put the new board in check it over carefully, do those resistance readings on it especially on Q661. I recently bought a "working" tnpa5081. Found Q661 shorted right away. Then noticed another IGBT was totally exploded. The exploded IGBT was clearly visible on the guys ebay pic too once I knew what to look for so was not difficult to get a refund.

Yes check buffers for shorts. Make sure all is screwed in tightly and properly connected. You can test the SC with SC50 jumper in before making connection between SC and buffers.