Panasonic TC-P42GT25

[tw2005]

Re: Panasonic TC-P42GT25

I think I'm going to go insane with this one, any chance you can take a shot of the measurements with the meter in view? one with the 200, one with the 2000. I want to see the whole meter.

When you say 2000, 2000ohms or 2000K. if it's 2000k and reads 314 that would be 314K?

[mpj31]

Re: Panasonic TC-P42GT25

Ok here are the pictures requested. All different readings depending on the setting used ranging from 200 to 2000k.

https://www.dropbox.com/s/ws235u0s2a...2019.07.10.jpg

https://www.dropbox.com/s/ayj68bnx17...2019.07.25.jpg

https://www.dropbox.com/s/faoun2n6i7...2019.07.40.jpg

https://www.dropbox.com/s/lhfr56yuvd...2019.07.53.jpg

https://www.dropbox.com/s/bk6hutcbng...2019.08.05.jpg

the multimeter setting didnt really come in on most pictures... but just see position of the dial... it increases in a clockwise direction, so the last pic is the highest at 2000k.

[tw2005]

Re: Panasonic TC-P42GT25

So

200ohm = 194.8

2000ohm = 315

20k = 4.17

200k = 23

2000k = 188

This is what the op manual says, just as confusing as the results.

1. Set the function switch to the highest $# position.

2. Insert the black test lead banana plug into the

negative (COM) jack

Insert the red test lead banana plug into the

positive $ jack.

3. Touch the test probe tips across the circuit or

part under test. It is best to disconnect one side

of the part under test so the rest of the circuit will

not interfere with the resistance reading.

4. Read the resistance in the display and then set

the function switch to the lowest $ position that is

greater than the actual or any anticipated resistance. The display will

indicate the proper decimal point and value.

I'm totally confused now. So does that mean set to 2000K, you see 188 so you go to 200ohms and 194.8 is the result?

unless someone else can throw some light on how these work. I use an autoranging Fluke.

Only thing for me to suggest is if you know someone who has a higher quality meter or we keep sniffing around the SC board in continuity mode and check out the transistors on the heatsinks for dead shorts.

If it has failed and low resistance at Sc2, there should be some shorted out transistors .

This is turning out to be more difficult than it should be for identifying a bad SC board especially a TNPA5081 which I know fairly well.

[mpj31]

Re: Panasonic TC-P42GT25

What is the resistance supposed to be?

Not sure where to go next. Is there any possibility its not the SC board? If its the SC board should I just try to replace it? How much are these things anyway?


I was reading through this...

http://www.justanswer.com/electronic...7u-failed.html

would it be smart to do the voltage test this way?

If I put the black lead on a screw as a ground and then test the white metal pin on the WHITE side (right side) of the SC2 connection I get a reading of 0.00... either I'm not doing it right or its short...

[tw2005]

Re: Panasonic TC-P42GT25

This is what my Fluke 73 gives on a Rev AF board for a 50". You should see something similar for resistance. This is at SC2, and the vsus cable removed.

With the black lead on gnd(pin 3, brown cable side), red lead on vsus(pin1, white cable side)

First application, expect around 300k ohms, this one was 286K , settled abound 276K.

Lift the red lead for a moment or too and apply and my meter then reads 2.4-2.5 megohms.

This is an auto ranging meter and it tells you what units it's measuring, ohms,Kohms,Mohms

In diode/continuity with the leads in the same position, short beep, then starts at 0.27 and the cct charges and steadily rises until it gets just over 2.05 , then O.L.

You could try diode mode and see if it produces a clearer result for us.

With the voltage test, you could backprobe SC2 with everthing connected and power on and see what vsus is doing.

If there is a dead short, you won't see much action and that's when usually SOS4 would be generated because the PSU is shorted.

Try it and also try this for me, leave SC2 connected but disconnect vsus at the SS (SS11) and power on.

Could it not be the SC? yeah, SOS1 traditionally is the A-board but i'm thinking it's a false trigger. You've also mentioned seeing SOS10 and SOS4 both of which can be associated to a bad SC which is fairly common fault.

My thinking is this, SOS1 is generated at the A-board. So no other board generates it and by disconnecting everything else from it and having the A-board power up with no blink codes suggests it's ok and maybe SC2 is not a dead short but low enough for the PSU to cut power at a moment which might be causing the A-board trigger a SOS1.

I can only confirm this for you. I had a 2010 HD 42", SOS4, yep vsus dead short but SS board failure (common fault)

I cleared the short by replacing the blown IGBTs and ended up with a SOS1.

This was the first TV I tried powering up just the A-board and the SOS1 remained on the bad board. It was not present on the good board and returned when i swapped the bad EEPROM onto the working A-board.

This was all done as you tried and you got no SOS1.

I don't know if anyone else has tried it so I can only tell you what happened in my case.

I'm trying to prove one way or the other whether the SC is good or not. We only need to find one shorted transistor to prove it's bad but i was hoping SC2 was going to be dead short (usually it is) but that Craftsman meter is not helping me with decisive results.

I think on a bad board from the UK I got, SC2 was not shorted but 3 transistors were. I just knew the common transistors that blew and the very first one I tried it was S/C.

If we find it's bad, I would replace it first, if you still had SOS1 then that was always going to be the case and more $$.

Assuming both are obtainable, could be up to $300 for both. Luck and availability when getting used boards.

If you go the other way and my hunch is correct then you just wasted money on a board.

Either way it's not going to be a super cheap fix. If it's just the SC might get away with it under $100 for a board.


here's a list of IGBTs that i have seen fail over the three boards I fixed.

They all failed dead short across all 3 pins so it's a no brainer for finding a bad one .
use diode mode, i'm not trusting the resistance, they will be dead short if they've failed.

Q661 would be the first one I'd check, drop the 16 prefix and that's how the position is labelled on the board. the positions are from a 50, so if thety don't match the transistors will

Q16661 RJP63F3A
Q16402 DG3D5020
Q16403 DG3D5020
Q16421 DG3D4020
Q16422 DG3D4020
Q16621 30F125
Q16622 30F125
Q16452 45G128

[tw2005]

Re: Panasonic TC-P42GT25

I forgot to mention Vsus could be just under or over the 200V DC mark, start with 600V and if under 200v change to the 200V range.

[mpj31]

Re: Panasonic TC-P42GT25

This is what my Fluke 73 gives on a Rev AF board for a 50". You should see something similar for resistance. This is at SC2, and the vsus cable removed.

With the black lead on gnd(pin 3, brown cable side), red lead on vsus(pin1, white cable side)

Is this how I should be measuring SC2?

https://www.dropbox.com/s/5gf2gphudi...2021.19.54.jpg

Again I get about 315.. which is close to your 300 number you were saying.

Try it and also try this for me, leave SC2 connected but disconnect vsus at the SS (SS11) and power on.

This changes nothing. Still SOS1 or SOS10 if I hold down power button.


Not sure how to test the IGBT's but I found your thread which helps locate them... any tips?

https://www.badcaps.net/forum/showthread.php?t=22610


EDIT: Ok so you are talking about testing those pins...on DIODE mode I get readings BUT I don't get a beeping noise on Q660. I get it on just about every other one. I also do not get a beeping noise at SC2. Should I?

[tw2005]

Re: Panasonic TC-P42GT25

I simply don't know what your meter is doing. If it's 315ohms, that's bad, if it's 315 000 ohms that's ok.

Go to Q661, should be a RJP63F3A transistor, pick any leg, and probe in diode mode each of the other 2.

What happens? Is it a continuous beep, what does the meter read?

whenthe leads of the meter are shorted does the meter continually beep and read 0?

[mpj31]

Re: Panasonic TC-P42GT25

This appears to be a video of someone using a very similar multimeter... looks just like mine.

http://www.youtube.com/watch?v=BCd1nk1b5AY

Go to Q661, should be a RJP63F3A transistor, pick any leg, and probe in diode mode each of the other 2.

What happens? Is it a continuous beep, what does the meter read?

I get a reading of 015 and its a continuous beep.


When I touch the red and black leads together without anything else touching its a continuous beep and shows 0.

[tw2005]

Re: Panasonic TC-P42GT25

This appears to be a video of someone using a very similar multimeter... looks just like mine.

http://www.youtube.com/watch?v=BCd1nk1b5AY




I get a reading of 015 and its a continuous beep.


When I touch the red and black leads together without anything else touching its a continuous beep and shows 0.

Right, maybe we are moving forward again. Sounds shorted which is what i was expecting. That one always seems to short on the boards when they fail.

A continuous beep means continuity or low resistance. This means the transistor is shorted

At Q661 with my meter in diode, black lead on G(gate), red on E(emitter) I get a brief beep and a reading around 0.6. In resistance in the same position I get 2229ohms.

The G,C,E markings are on the underside of the board, they're IGBTs

set the meter to 200ohms and probe Q661 again where you got the constant beep and give me the reading.

Can you go around the rest of the board now and do the same in diode mode and probe all the other IGBTs ( marked Q...) on the heatsinks.

I want to know, if it continuously beeps and the meter reading. Note the results for all and post up.

On the ones that continuously beep, set meter to 200ohms again and give the reading in ohms.

[tw2005]

Re: Panasonic TC-P42GT25

Had a look at the video, looks logical enough. still don't get what yours is doing.

Is it a brand new meter and brand new battery?

[mpj31]

Re: Panasonic TC-P42GT25

Got the meter in September of this year.

[mpj31]

Re: Panasonic TC-P42GT25

Q16661 RJP63F3A --- 016 cont beep
Q16402 DG3D5020 --- starts off around 16 then drops to 000 cont beep
Q16403 DG3D5020 --- 015 cont beep
Q16421 DG3D4020 --- 011 cont beep
Q16422 DG3D4020 --- 005 cont beep
Q16621 30F125- no beep, multimeter shows 1. ... this appears to have a lot of resistance because all of my ohm tests give a 1 except for what I think is the highest setting gives a reading.

Anyway to test one of the other boards to make sure that its not just the multimeter being faulty? Is there something on the A board I can test similarly to see if its beeping or not beeping?
Q16622 30F125
Q16452 45G128

[tw2005]

Re: Panasonic TC-P42GT25

Nothing springs to mind, you said it goes 0 and beeps with the probes shorted which is correct.

If you have a potentiometer (variable pot resistor, or what was used for volume control before it all went digital) , hook the probes to the center and outer leads and adjust to continuous beep and then back it off until it stops, then measure resistance to see where the threshold is.

I think your manual says 30ohms or below triggers the continuous beep, mine will at 100ohms or below.

that's why i asked for a resistance at the beeping ones just for comparison.

Anyway I think this SC is deceased.

[mpj31]

Re: Panasonic TC-P42GT25

I do not have one of those potentiometers. With that said how can I test other boards to make sure they are working so i just order SC and not waste money on just that board if it doesn't work?

[tw2005]

Re: Panasonic TC-P42GT25

That's the best I can do.

You could have a dig in here 2010 FHD Guide

There's cable disconnection guide on p61 and results.

The last one , A20(A33), A31,A32. Might be interesting to see what happens there, probably end up with SOS1 again going on previous results but I'm curious.

the tabled results are based on a TV that is working.

For me based on what you are telling me.

We have shorted Transistors on the SC

No SOS1 when the A-board is powered up on it's own, for me that should be a pass.

You could try that one again and check out the vsus at the PSU and any other voltages to verify they are correct and in fact the A board is running.

If it's still tuned in you could hook the antenna up and I would expect audio, could also hook the monitor out to another display and see video. You won't see OSD .

You could backprobe the Vsus line at the SC with everything connected and power on to measure what it gets to.

Either way if you're happy you've probed those transistors as short, then SC board is the minimum needed at this stage.

You still need to do the resistance tests on the buffer boards to be sure they are ok so you don't blow another.

You can try it and see what the meter says and try diode mode and if there are no shorts at least it should not blow the Sc if still bad.

If anyone else has some ideas lets hope they share them.

like I mentioned earlier, I had a 2010 HD and it's the first time I failed to get it 100%.

SOS4 ,Shorted Vsus at SS, fixed, to then have SOS1, fixed, to have damaged C buffer, and then running with poor picture,

What can i say , sometimes it goes to crap.

This model usually ,most get it going with a SC, sometimes need buffers and occasionally an A board is bad.

yours is unusual with a bad SC and a SOS1, but then we have shorted transistors but no dead short at SC2.


There are no gaurantees with free advice on forums.