Panasonic TC-P42GT35 1 Blink break down troubleshooting

[Shinju]

Hey all!

I am making this post for any future folks finding issues with this Panel. There are a few threads that had some good details but no follow up from the OP's on the outcome of their fixes.

So here is what we got.

Panasonic TC-P42GT35 1080p 3D Smart Plasma Display.

The unit when powered up. It was only giving me a 1 blink SOS, So I broke the panel down and did the following steps to figure out it was a blown SC board (pretty typical failure on these newer Panasonic plasma displays).


Anyway so I pulled the back off and visually inspected the boards (the seller told me he heard a loud firecracker pop when the panel died) so I was expecting to see some carnage.... None was found.

Next step I disconnected P2 and P11 (SC and SS power plugs) and then I disconnected plug 35 on the power supply (this feeds power to the bottom C buffer boards)

Then I proceeded to disconnect the 3 white flat ribbon cables being fed to the mainboard.

This test is to determine SMPS and Mainboard functionality. The TV was able to power on and the red LED stayed solid. (This is good)

Wait about 20-25 min before connecting anything or wait till voltage drops below 25v this keeps the boards from being damaged.

Next I reconnected all the plugs except the P2 plug going to the SC board this also includes the ribbon cable from the SC to the Mainboard (this must be plugged in to allow the SOS detection to report a SOS 7 failure).


After connecting everything but the SC board power feed the panel turned on to display a SOS 7 fault, this is what we are looking for this means the SC board has a possible short. One other way to tell is to put your DMM into Diode mode and look for low or zero resistance or a beep. This means the SC board has failed.

After this test is complete again wait a few min to allow voltage to discharge and then reconnect the SC board power feed connector.

Once this is done power up the unit again and you should see a SOS 4 blink.

Also visually inspect your SU/SD IC's for any possible faults/open circuits or blow holes.

These steps apply to most Panasonic Plasma displays. I would also like to thank Tom66 and TW2005 I have learned quite a bit about plasma displays and troubleshooting from you two


Since I cannot find the parts to repair this SC board or a repair kit I am sending it to ModusLink for them to repair it.


Also I do have a question, this is the first plasma panel I have ever seen with out a voltage legend inside the unit. I have no idea what the voltages are supposed to be, I did take them and I believe it was 202/60. I looked everywhere for a sticker but was not able to find one.

I will update when I get my repaired SC board.

Thanks for reading!

[Shinju]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

Crap, anyway to edit the post/topic? I meant G25 not G35!

[tw2005]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

https://www.badcaps.net/forum/showth...ght=tc-p42gt25

Sounds similar story to this but never got a confirmed fix. Did sound like it was sc as well which is interesting to see 1 blink now for 2 tvs .

[tw2005]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

What parts could you not find? Have you read my tnpa5081 thread? For voltages just leave it as it is. Preset and controlled by the a board. They stopped labelling voltages 2010 on.

[Shinju]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

I think the IGBT for this board were on back order, I had a 30% off purchase on Moduslink so the repair cost was the same as if I was to get the parts and DIY it. 67 bucks isn't bad at all.

[Shinju]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

So...

I get the rebuilt SC board in and no go. The panel primes for a second, click and 7 blink.

Everything is connected good, screws are down tight. Not sure what else it could be unless the buffer board is toast, panel is toast or the SS board is toast.

[Shinju]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

This unit has both SD/SU on one buffer. Would a bad buffer cause this? Would it also damage my SC board?


7 Blinks SOS: Pin 93 of the MPU IC9003 monitors the status of the SC, SU, SD board. During normal operation, the photo-coupler PC6480 outputs a low to pin 93. If the SC, SU, or SD board becomes defective, a high is provided to pin 93. As a result, the unit shuts down and the power LED blinks 7 times.

[tw2005]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

This unit has both SD/SU on one buffer. Would a bad buffer cause this? Would it also damage my SC board?


7 Blinks SOS: Pin 93 of the MPU IC9003 monitors the status of the SC, SU, SD board. During normal operation, the photo-coupler PC6480 outputs a low to pin 93. If the SC, SU, or SD board becomes defective, a high is provided to pin 93. As a result, the unit shuts down and the power LED blinks 7 times.

possibly but if the buffers were shorted I don't think the panel would prime. try the buffer isolation. remove the 4 Vfg bolts from the Sm board, disconnect the 3 connectors from the SC to the Sm, jumper SC50 pins together and turn Tv on and see if still 7 blinks.

[tom66]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

I think it would be possible to get the panel to prime if the buffers were short, as the -Vad is needed for priming but not Vscn, but purely conjecture on my part here.

[tw2005]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

I'm not brave enough to try a shorted set to test the theory

[tom66]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

Indeed, could cause other damage.

Worth checking -Vad, Vscn and Vset (if present)

Shinju, do you have a scope available? (I keep forgetting on here who has a scope...)

[Shinju]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

Tom66

I do have a 60hz ATTEN digital scope. I can run some tests when I get home from work.

TW2005

I can try your method too, i hope that I didn't already damage the SC!

[tom66]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

I'm thinking you might just have low -Vad, or Vscn, you couldn't get prime with missing/very low -Vad, can't remember if they generate the supplies separately or on the same transformer on this model.

[Shinju]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

So when I fired it up again last night after doing a quick visual inspection on the buffer and re-tightening all the screws and re-seating all the ribbons ect the screen didn't prime but did a strange sparkle then shut down and fired up a SOS 7 again.

I ordered a new buffer since it was super cheap, and it was tested from a reputable seller.

How would I go about testing Vscn and -Vad how it is now?

[tw2005]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

So when I fired it up again last night after doing a quick visual inspection on the buffer and re-tightening all the screws and re-seating all the ribbons ect the screen didn't prime but did a strange sparkle then shut down and fired up a SOS 7 again.

I ordered a new buffer since it was super cheap, and it was tested from a reputable seller.

How would I go about testing Vscn and -Vad how it is now?

I would have done that isolation test first to determine if Sc alone has an issue. If so, send it back.

Then I would have resistance checked the SM board.

Your playing with fire if the condition of the buffers is unknown,.

[tom66]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

Usually -Vad/Vscn marked somewhere on SN/SC board.

[Shinju]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

I would have done that isolation test first to determine if Sc alone has an issue. If so, send it back.

Then I would have resistance checked the SM board.

Your playing with fire if the condition of the buffers is unknown,.

I did that before posting the first post after I got the SC board in after it was repaired. I was just mentioning what was going on with the screen behavior.

I will try the Isolation test tonight to make sure. what board has the jumper SC50 pins? I assume the SC board?

[tw2005]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

I did that before posting the first post after I got the SC board in after it was repaired. I was just mentioning what was going on with the screen behavior.

I will try the Isolation test tonight to make sure. what board has the jumper SC50 pins? I assume the SC board?

you have me confused now. already did what? If the Tv is going 7 blink it's sc or sm or both.

I'm only interested in what you've done now since receiving the repaired board and still 7 blinks.

SC 50 is top left corner next to that large white resistor.

make sure the sm is disconnected and the 4 Vfg screws removed. We had someone do something here on same model and the Sm and SC went up in smoke.

[Shinju]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

you have me confused now. already did what? If the Tv is going 7 blink it's sc or sm or both.

I'm only interested in what you've done now since receiving the repaired board and still 7 blinks.

SC 50 is top left corner next to that large white resistor.

make sure the sm is disconnected and the 4 Vfg screws removed. We had someone do something here on same model and the Sm and SC went up in smoke.

Got it.

I haven't done anything after what I said when I originally put the SC board in the panel after getting it back.

[Shinju]

Re: Panasonic TC-P42GT35 1 Blink break down troubleshooting

Panel is up and running with SM board out and jumper SC 50 applied.

Solid red LED, I can hear SS and SC hum.

Vsus 209
Vda 60

SC voltages

TPVad -206
TPVSCN -58.7


SS

TPVSUS 209
TPve 134.2