2010 Panasonic TC-P42GT25 Plasma Troublshooting

[rogerpjr]

I had fooled with this TV a couple years ago and kind of set the project aside but now I need to get it fixed. I got the 10 blink code and replaced the A board with one I got off eBay as that fixed another TV I had. This time it didn't work. I still have the original A board.

I tried disconnecting SC2, SS11, P35 and the 3 white ribbons connected to the A board and powered it on and still got the 10 blinks. Both fuses on the P board are good by checking their continuity. One thing I did notice is that there is what looks like a little light bulb, marked S101, just to the right of where the main power wires connect. When I powered up the set, it doesn't light up, but I don't know if it should or not. I checked the continuity of the leads coming out of the bulb and get nothing.

I am guessing by disconnecting what I did, this narrows the problem to either the A or P boards. Is this correct? Can anyone give me some specifics on what to check next?

[Brian_STI]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

Are you sure you have the right suffix? They are sort of complicated and I've seen a lot of incorrectly labelled boards. Check shopjimmy, they should show you how to read the suffix, it's done with some surface mount caps and a table printed on the board. If those don't match, it won't work.

I'm not at the shop so I can't look it up but (based on memory) I believe you're right that a 10 blink on the GT25 is the A board. Are you getting your VS and VA voltages at all? Does the screen prime? You'll want to check as you plug it in, they'll drop within a few seconds.

I'll try to remember to verify the blink code tomorrow at the shop.

[rogerpjr]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

Had no luck getting a response from ShopJimmy. Is there an easy way to check this suffix code thing?

Am I right in my guess that disconnecting what I did narrows the problem to the A or P boards?

Any suggestions on how to test the A & P boards?

[Moreno83]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

Well normally 10 blinks is the power board and not the A board. You need to check the parts on the power supply for shorts. They are labeled with Q and D in front of it. For example : Q512 and D401.

Also remove the power supply and check the back of the board.

Q512 --> Diode mode and measure the outer legs. ( Beep is bad )
D401 --> Diode mode and put the black prope on ground and red on one leg. ( Measure both legs and constant beep is not good ).

Don't forget , can be that you must remove the diode's out of the circuit for better measurement.

[Moreno83]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

Am I right in my guess that disconnecting what I did narrows the problem to the A or P boards?

Yes and no. If you remove these cables you get different error codes because you remove connections from the mainboard. 10 blinks is usually a problem with the power supply.

[rogerpjr]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

I get the same 10 blink code whether the cables are attached or not.

[Moreno83]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

You probably have a 90% chance that the power supply is bad. Mainboard is trying to do a cycle of tests before it turns on. Its testing all connections , those tv's are full with sensors.

If you replace the power supply you might get lucky and the tv is fixed OR you get another blink code. It can be that a SC board shorted the power supply.

[rogerpjr]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

I have ordered a new power supply board. Should I just put it in with all the cables I originally disconnected remaining disconnected first just in case the SC caused the problem and how will I know if the SC won't fry the new power supply?

[tw2005]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

I have ordered a new power supply board. Should I just put it in with all the cables I originally disconnected remaining disconnected first just in case the SC caused the problem and how will I know if the SC won't fry the new power supply?

Get yourself a multimeter and check the resistance across SC2 and see if it's shorted.

The P board normally survives a shorted SC board but I guess it's conceivable it may get damaged.

Without checking what voltages are present at startup it is really just guessing whether it's A or P.

The training guides suggest SC or A as main culprits .

It's certainly not unheard of of someone buying a used A board to have the same fault or be faulty.

[dj01fad]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

hello Roger.

I had also a 10 blink 42GT20, and the error was coming from the SC board. try this:
remove the connection from the A board to the D board. If it's a problem with A board, the TV should start with a full white screen. If not, then you have to check the SC board. I doubt that you have a problem with the P board. on my tv, any connection I would remove (from the SC or the SS board), except the one from A to D, I had 10 blinks.

[tw2005]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

hello Roger.

I had also a 10 blink 42GT20, and the error was coming from the SC board. try this:
remove the connection from the A board to the D board. If it's a problem with A board, the TV should start with a full white screen. If not, then you have to check the SC board. I doubt that you have a problem with the P board. on my tv, any connection I would remove (from the SC or the SS board), except the one from A to D, I had 10 blinks.

I checked this model out and it's unusual in comparison to the other 3D models of this series.

does not use a D board and the SC is the same version in both the 2D and 3D models.

That's according to the service manual, of course pictures are always nice to see what's what.

[rogerpjr]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

Yep, this one doesn't have a D board or SU/SD. There is a combined SM buffer board. When I check the resistance across the legs of SC2 it is not continuous (no beep on my Fluke 77 meter).

My replacement A board came from TV Parts Central and they guaranteed it to be not DOA. It has the same suffix indication as my original. There are no components inside the indicated block and a row of open holes below the solder pads.

[Moreno83]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

Ok my mistake. I was sure that the power supply was gone because he said he removed all cables and he still gets 10 blinks from the a board.

[tw2005]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

Yep, this one doesn't have a D board or SU/SD. There is a combined SM buffer board. When I check the resistance across the legs of SC2 it is not continuous (no beep on my Fluke 77 meter).

My replacement A board came from TV Parts Central and they guaranteed it to be not DOA. It has the same suffix indication as my original. There are no components inside the indicated block and a row of open holes below the solder pads.

Ok my mistake. I was sure that the power supply was gone because he said he removed all cables and he still gets 10 blinks from the a board.

Well, we should find out when the P board goes in, but if it still 10 blinks, then what are you going to do?

[rogerpjr]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

Does the fact that SC2 was not continuous across the legs indicate that the SC board is still good?

I really don't know what happens if I still get 10 blinks. I did just re-download the 2010 training manual and I guess I will start at the beginning and check it all again. The guide is a bit confusing as to knowing which board(s) cause the problem though. I'm not sure Panasonic really knows or cares. Like everyone keeps saying, it was designed to fail so you would just throw it out and buy another one. Unfortunately I'm from the old school and want to repair something that should still be good.

[Moreno83]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

I have the same tv with the same power supply. Im using that tv for test purposes. I'll measure voltages on the power supply with just the mainboard attached. Let's see if the voltages are the same.

Is the SC board in this tv also the TNPA5349?

[tw2005]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

Does the fact that SC2 was not continuous across the legs indicate that the SC board is still good?

I really don't know what happens if I still get 10 blinks. I did just re-download the 2010 training manual and I guess I will start at the beginning and check it all again. The guide is a bit confusing as to knowing which board(s) cause the problem though. I'm not sure Panasonic really knows or cares. Like everyone keeps saying, it was designed to fail so you would just throw it out and buy another one. Unfortunately I'm from the old school and want to repair something that should still be good.

no. they don't all go short at sc2, if it did 4 blink code is common. If the SC was bad you could amost be 100% assured Q661 will be shorted across its legs.

[rogerpjr]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

SC board is TNPA5081AH

I'll check Q661 tonight

[rogerpjr]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

Checked both Q660 and Q661. Got no reading (no beep) on either of them. I guess that means at least they are good.

[Moreno83]

Re: 2010 Panasonic TC-P42GT25 Plasma Troublshooting

Any idea when you get the power supply?