Panasonic TX-P37X20B

[delphiplasma]

Hi,

I have an issue with this plasma TV. When switched on from 'cold' the first 2 minutes of the image is obscured by vertical wide red and blue columns, as can be seen from the attached photo. This is the same for all inputs.
Can someone please advise which board is causing the issue.
Your help would be greatly appreciated.
Thanks in advance.
Delphi

[dick_barton]

Re: Panasonic TX-P37X20B

There's a service manual in the following thread
https://www.badcaps.net/forum/showth...ght=TX-P37X20B

How to run the self test on a plasma display control board / logic board
https://www.badcaps.net/forum/showthread.php?p=534846

[tw2005]

Re: Panasonic TX-P37X20B

Hi,

I have an issue with this plasma TV. When switched on from 'cold' the first 2 minutes of the image is obscured by vertical wide red and blue columns, as can be seen from the attached photo. This is the same for all inputs.
Can someone please advise which board is causing the issue.
Your help would be greatly appreciated.
Thanks in advance.
Delphi

A-board, one of the BGA chips has broken solders highly likely. Trying warming that board with a hair dryer before you turn it on and the problem may not be there on startup but either you'd have t replace the board or find someone who do do BGA work.

[ReeceyBurger123]

Re: Panasonic TX-P37X20B

a-board, one of the bga chips has broken solders highly likely. Trying warming that board with a hair dryer before you turn it on and the problem may not be there on startup but either you'd have t replace the board or find someone who do do bga work.

+1

[delphiplasma]

Re: Panasonic TX-P37X20B

Thanks for your help. I was hoping it wasn't the A board, as they are impossible to find. I'll do the confirmation tests as suggested and let you know the results.
Once again, thanks for the quick responses.

[ozzy214]

Re: Panasonic TX-P37X20B

You can always try the "oven trick" if the board is impossible to find. Fixed quite a few dv2000 and dv6000 back in the day with no ill effects. Most customers got another year or two out of the machine with zero failure.

I believe its 375 or 380 in the oven. Set the board on a glass bowl safe for oven use to keep it off the rack. 10 mins cook time and let cool.

Look on google for correct temp. I recommend this if all else fails and what do you have to lose? TV is already broke!

[delphiplasma]

Re: Panasonic TX-P37X20B

Thanks for the tip. The TV is fine after 2minutes. I'll first confirm issue with hairdryer and then remove the board and clean it up, maybe run solder iron over it. Oven idea is very interesting.

[delphiplasma]

Re: Panasonic TX-P37X20B

Okay...So I managed to get a replacement board off E-bay. I put it in last night powered up and it looked like the bars had gone. However, it only stayed powered on for 3 seconds after which it went into standby with the red light flashing a sequence of 4 flashes. Tried powering back on...Green light flashing quickly, then back to the red light sequence. I dropped the old board in and the same thing is happening! Arggggg!!

[tw2005]

Re: Panasonic TX-P37X20B

Okay...So I managed to get a replacement board off E-bay. I put it in last night powered up and it looked like the bars had gone. However, it only stayed powered on for 3 seconds after which it went into standby with the red light flashing a sequence of 4 flashes. Tried powering back on...Green light flashing quickly, then back to the red light sequence. I dropped the old board in and the same thing is happening! Arggggg!!

Check the SS board RJP30E4. Also check SN board especially the recovery cct where the SS connects to.

Vsus most likely shorted.

I'd replace the M81735P driver on the SS too for good measure if those IGBTs are shorted

[delphiplasma]

Re: Panasonic TX-P37X20B

Thanks. I wonder if the board I purchased off eBay was actually the cause of the death of the other components or those other components were already on their way out?

[delphiplasma]

Re: Panasonic TX-P37X20B

Just a quick query, I gather the 4 blink code, which relates to power supply board issue is being caused by the short circuit on the other boards? I suppose if disconnecting those boards, if the led blink remains 4 blinks then it would be a P board issue.

[delphiplasma]

Re: Panasonic TX-P37X20B

Okay...so I disconnected the right side board and still flashing 4sos. However, after reconnecting right side board and disconnecting left side board I get 2sos. So does this mean that the left side board is duff together with the A board? Thanks

[tw2005]

Re: Panasonic TX-P37X20B

Okay...so I disconnected the right side board and still flashing 4sos. However, after reconnecting right side board and disconnecting left side board I get 2sos. So does this mean that the left side board is duff together with the A board? Thanks

No idea. Disconnect P2,P11,P35, the 3 white ribbons at the A-board, turn it on and see if it passes.

Turn it off and don't reconnect P35,P2,P11 for a good 5-10 mins for the residual voltage to drop as a spike especially P35 can damage the panel.

[delphiplasma]

Re: Panasonic TX-P37X20B

Okay...I disconnected the 3 ribbons to the A board and still get 4 flashes. I checked the resistance of the SC and SS main voltage input terminals and can confirm there are no short circuits. Maybe the supply to the A board has been affected? 15v or 5v??

[delphiplasma]

Re: Panasonic TX-P37X20B

Sorry, I didn't disconnect the P cables. It passed the test and remained a stable green light.

[delphiplasma]

Re: Panasonic TX-P37X20B

I have just read the link dick Barton included in the second post. I'll check the resistance at the connectors on the SS and SC board. Altough initial measurements suggest no problems? Maybe the power board is at fault?

[tw2005]

Re: Panasonic TX-P37X20B

Sorry, I didn't disconnect the P cables. It passed the test and remained a stable green light.

That would mean either sn or ss. May not be dead short but low enough to trip 4 blink and it would not take much to check for shorted transistors on either board

[delphiplasma]

Re: Panasonic TX-P37X20B

What does P35 supply? Can I connect P35 and power up to see if it still passes the green light test, which would definitely condemn the SN/SS boards? Unless, P35 is an auxiliary supply for the SN/SS boards? I'll do some more measurements, but am thinking more likely to be the SN board. Will get back with my results, when I get the time.

Thanks for the invaluable help so far. It's a shame it had to come to this, when the original problem I could have lived with.

[tw2005]

Re: Panasonic TX-P37X20B

p35 powers the panel through the c boards and ribbons. You probably could do that but be warned if you disconnect or reconnect whilst there is any residual power(stored in the caps) and spike , good chance the panel can be damaged.

Highly unlikely that is your 4 blink. You could hook it all up and disconnect p2 and if it went 7 blink then the 4 blink was the SN board, if still 4 blink then disconnect p11, reconnect p2 and see what happens there

[delphiplasma]

Re: Panasonic TX-P37X20B

Thanks. I've been doing some resistance checks on the semiconductor devices, such as the RJP30E's on the SS board and D461, D725 and Q441 on the SC board. When we talk about 'shorts' are they straight 0ohms, or is 0.17ohms - 17ohms okay? I'm testing the devices in circuit. Thanks for the P35 explanation. I will try the P2/P11.
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