Panasonic sc tnpa5081 rebuild

[dolivas27]

Re: Panasonic sc tnpa5081 rebuild

Do you know if I can power the TV on with the buffers connected to the SC but not connected to the screen?

Still wondering if the screen has a problem.

[dolivas27]

Re: Panasonic sc tnpa5081 rebuild

I don't think a tester will help. try googling IGBT test or FET test, with multimeter.

Diode mode.

I'm baffled how it works ok until the buffers are hooked up

I know how to test the IGBT & FET with a DMM that is the thing they test fine.

They turn on and off ok and don't have any shorts.

The transistor tester would have caught the bad Q608 as it would have tested for the leakage. I got lucky catching it with the DMM

Ok I am going to rebuild this board one more time and see if I can get it to work again with out the buffers.

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Do you think if one of the transistors were bad it would power up with out the buffer connected?

I need to purchase a transistor tester.

I don't think a tester will help. try googling IGBT test or FET test, with multimeter.

Diode mode.

I'm baffled how it works ok until the buffers are hooked up

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

In circuit or out?

I have several here and none read that and the ones that I installed the last go around were pulled from a working TNPA5784 SC board

in cct, everything I've quoted pretty sure is in cct

[dolivas27]

Re: Panasonic sc tnpa5081 rebuild

Do you think if one of the transistors were bad it would power up with out the buffer connected?

I need to purchase a transistor tester.

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Yes that is correct and I am testing them out of Circuit.

If you can test a Q661 / RJP64F4A out of circuit I have a felling I have some bad parts just not sure which ones.

The RJP64F4A I received from utsouce look bad I order some more off of eBay from a guy in the states and they look much better?

can't help. Just relocated a whole house, took me 3 boxes just to find a 5081 to probe, spares , you got no chance of me finding that and i think I'm out of the rjp63F3a.

have not ordered for ages but I've had no issues but always a chance you could. also these need to be probed in a way to turn them on to see if they are ok but as for straight resistance I don't think you have much chance there, so long as they're not shorted.

I've tried comparing originals to supplied for resistance and they never match but they've all worked.

I was hopeful the 30F125 were still in and had a low resistance since you did not mention these as replaced which normally they go but not always dead short, maybe a few hundred ohms.

Going by an earlier post someone else failed on a 54" board. I'm out of ideas biut If I was in this situation I'd try a 50" board known to be good and if that blew then something is killing them.

[dolivas27]

Re: Panasonic sc tnpa5081 rebuild

somewhere amongst all that I'd expect to see 47K ohms as a reading

In circuit or out?

I have several here and none read that and the ones that I installed the last go around were pulled from a working TNPA5784 SC board

[dolivas27]

Re: Panasonic sc tnpa5081 rebuild

got a ref for 1,2,& 3? Like g,c,e?

Yes that is correct and I am testing them out of Circuit.

If you can test a Q661 / RJP64F4A out of circuit I have a felling I have some bad parts just not sure which ones.

The RJP64F4A I received from utsouce and they look bad.

I order some more off of eBay from a guy in the states and they look much better?

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

somewhere amongst all that I'd expect to see 47K ohms as a reading

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Ok here is what I have for the 30F125 Transistors

They are Q621 & Q622

Not sure the order now as they are both out of the board.

1st 30F125

Pin 1 NEG
Pin 2 POS = OL
Pin 3 POS = OL

Pin 1 POS = OL
Pin 2 NEG
Pin 3 POS = .456M

Pin 1 POS = OL
Pin 2 POS = .470M
Pin 3 NEG

2nd 30F125

Pin 1 NEG
Pin 2 POS = OL
Pin 3 POS = OL

Pin 1 POS = OL
Pin 2 NEG
Pin 3 POS = 1.54M

Pin 1 POS = OL
Pin 2 POS = 14.9M
Pin 3 NEG

The both seem to test good in diode mode but the resistance looks off.

If I test in diode mode and put the NEG on PIN 3 and POS on Pin 1 to turn on I get 1.84V on both.

What do you have on yours?

got a ref for 1,2,& 3? Like g,c,e?

[dolivas27]

Re: Panasonic sc tnpa5081 rebuild

Ok here is what I have for the 30F125 Transistors

They are Q621 & Q622

Not sure the order now as they are both out of the board.

1st 30F125

Pin 1 NEG
Pin 2 POS = OL
Pin 3 POS = OL

Pin 1 POS = OL
Pin 2 NEG
Pin 3 POS = .456M

Pin 1 POS = OL
Pin 2 POS = .470M
Pin 3 NEG

2nd 30F125

Pin 1 NEG
Pin 2 POS = OL
Pin 3 POS = OL

Pin 1 POS = OL
Pin 2 NEG
Pin 3 POS = 1.54M

Pin 1 POS = OL
Pin 2 POS = 14.9M
Pin 3 NEG

The both seem to test good in diode mode but the resistance looks off.

If I test in diode mode and put the NEG on PIN 3 and POS on Pin 1 to turn on I get 1.84V on both.

What do you have on yours?

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Lead flipping does not matter is the the voltage the meter uses for the test.

I was in contact with fluke about the discrepancy in readings and here is what I found out.

The Fluke 87V uses 8V for the resistance reading but remember that changes with the range.

The Fluke 79III / 75 use 3v and again changes with the range.

I could never get the 3Mohm reading you were talking about on the Q521 / Q551 it was driving me nuts so I decided to go out to my truck and get the Fluke 79III I was then able to get the correct readings.

So as you can see the way the resistance was measured makes a big difference.

there you go, I just learnt something but I did find the results were completely different if the polarity is switched or at least was impossible to get accurate. I guess since these are all in cct it is just a guide but if those pnp/npn were bad I think resistance was obviously low or shorted. I have not had to relace many of those on this board.

[dolivas27]

Re: Panasonic sc tnpa5081 rebuild

did you flip the leads around to see if they changed? I have a feeling I may have tried a different meter at work once and got weird readings, may have been an 87 or an Agilent.

Going on the 79 it does appear both sets are ok and I'd be using them on those figures.

Lead flipping does not matter is the the voltage the meter uses for the test.

I was in contact with fluke about the discrepancy in readings and here is what I found out.

The Fluke 87V uses 8V for the resistance reading but remember that changes with the range.

The Fluke 79III / 75 use 3v and again changes with the range.

I could never get the 3Mohm reading you were talking about on the Q521 / Q551 it was driving me nuts so I decided to go out to my truck and get the Fluke 79III I was then able to get the correct readings.

So as you can see the way the resistance was measured makes a big difference.

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Here are the reading on the buffer boards.

I will explain more about the Fluke 87V reading later that is why I asked you about the meter you used.

I will have to check the suffixes

Do you think I could have some bogus transistors from China?

did you flip the leads around to see if they changed? I have a feeling I may have tried a different meter at work once and got weird readings, may have been an 87 or an Agilent.

Going on the 79 it does appear both sets are ok and I'd be using them on those figures.

[dolivas27]

Re: Panasonic sc tnpa5081 rebuild

can you have a look at the board and find the 30F125 IGBTs if it has them, tell me the location numbers too, get a meter and do resistance across all combos of 2 legs please and report back

Ok give me a second I was reworking the board right now to see what has blown again.

[dolivas27]

Re: Panasonic sc tnpa5081 rebuild

Here are the reading on the buffer boards.

I will explain more about the Fluke 87V reading later that is why I asked you about the meter you used.

I will have to check the suffixes

Do you think I could have some bogus transistors from China?

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

can you have a look at the board and find the 30F125 IGBTs if it has them, tell me the location numbers too, get a meter and do resistance across all combos of 2 legs please and report back

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Ok I need a little help with this one.

Ok so I picked up this unit cheap to try and repair it. Model # TC-P54G25

The unit has the 7 blink code and of course the problem is the SC board. or so I thought

TNPA5081 Rebuild Notes
1st Repair Attempt
Replaced = Not sure if it was Bad

IC501 - Replaced
IC521 - Replaced
Q421 - Shorted
Q422 - Shorted
Q423 - Shorted
Q401 - Shorted
Q402 - Shorted
Q403 - Shorted
Q452 - Shorted
Q661 - Shorted
D481 - Shorted
Q818 - Replaced
IC771 - Replaced
IC774 - Replaced
IC691 - Replaced
IC773 - Replaced
Q702 - Replaced
Q521 - Replaced
Q551 - Shorted
Q660 - Shorted
Q701 - Replaced

2nd Repair Attempt
I retested everything again like I was starting the repair from the beginning and here is what I found. I was looking at the flow chart and Q608 jumped out at me as a possible problem part. I'm wondering if others that have failed did not have a bad Q608 it was causing the Q661 to blow every time! I would not have found this bad part if I did not remove it from the circuit. What I found was the part was leaky when tested. I replaced it a reinstalled the board SUCCESS THE BOARD NOW WORKS!!!!

D642 - Shorted
Q661 - Shorted
Q608 - Leaky

Ok now it's time to connect the buffer boards and fire it up. Yes I measured the buffer boards and they looked good NO shorts. Being All excited I have it fixed I connect everything and plug it in and BANG a loud POP now a 10 Blink code! Test for shorts again and now the Vsus is dead shorted! Remove the SC2 connector and turn the set back on and have the 7 Blink code again! SC BLOWN AGIAN!!!!!


3rd Repair Attempt
Once again retest everything like I was starting the repair from the beginning. This is what I found blown I had to order PC461 from China so I had to wait 2 weeks for it to get here. Thinking I must have measured or missed a shorted buffer board I ordered both buffer boards while I waited for the PC461 to get here. I receive the buffers and tested them they look fine as do the originals?



D642 - Shorted
D641 - Shorted
Q661 - Shorted
Q402 - Shorted
Q421 - Shorted
Q422 - Shorted
Q423 - Shorted
D642 - Shorted
Q661 - Shorted
PC461 - Shorted

PC461 came in and I installed it and retested the board everything looks good. Reinstall it in the set and once again tested it without the buffer boards and the jumper installed in SC50. Everything powers up fine no blink codes!!!! Power cycled it several time to make sure it was fine. Reconnect the new buffer boards take some measurements to make sure everything looks good it does so decide to proceed with a power up. BANG LOUD POP and the SC BLOWS AGAIN!!!!

What am I missing could the Panel be bad? I checked it to Chassis ground and do not see any shorts. Could the SS board be causing this? but if that was case would it not blow with the buffers removed and the SC50 jumper installed? Going to rebuild the SC again but before I test it again with the buffers installed I need some help to figure out what is causing it to BLOW.

I've got no idea I'm afraid as I have not been in this situation. For me at least if it passes without the buffers, it's worked and kept working. Can't see it being the SS as it's not directly tied to it like the HD models.

Really weird 2 sets of buffers doing the same. Is everything in right, all bolts for the SC and teh sd/su? All ribons in straight on the sd/su, ribbon between the sd/su connected?

what pins on which buffers and what resistances did you get?

what suffixes are on the buffer boards?

[dolivas27]

Re: Panasonic sc tnpa5081 rebuild

Ok I need a little help with this one.

Ok so I picked up this unit cheap to try and repair it. Model # TC-P54G25

The unit has the 7 blink code and of course the problem is the SC board. or so I thought

TNPA5081 Rebuild Notes
1st Repair Attempt
Replaced = Not sure if it was Bad

IC501 - Replaced
IC521 - Replaced
Q421 - Shorted
Q422 - Shorted
Q423 - Shorted
Q401 - Shorted
Q402 - Shorted
Q403 - Shorted
Q452 - Shorted
Q661 - Shorted
D481 - Shorted
Q818 - Replaced
IC771 - Replaced
IC774 - Replaced
IC691 - Replaced
IC773 - Replaced
Q702 - Replaced
Q521 - Replaced
Q551 - Shorted
Q660 - Shorted
Q701 - Replaced

2nd Repair Attempt
I retested everything again like I was starting the repair from the beginning and here is what I found. I was looking at the flow chart and Q608 jumped out at me as a possible problem part. I'm wondering if others that have failed did not have a bad Q608 it was causing the Q661 to blow every time! I would not have found this bad part if I did not remove it from the circuit. What I found was the part was leaky when tested. I replaced it a reinstalled the board SUCCESS THE BOARD NOW WORKS!!!!

D642 - Shorted
Q661 - Shorted
Q608 - Leaky

Ok now it's time to connect the buffer boards and fire it up. Yes I measured the buffer boards and they looked good NO shorts. Being All excited I have it fixed I connect everything and plug it in and BANG a loud POP now a 10 Blink code! Test for shorts again and now the Vsus is dead shorted! Remove the SC2 connector and turn the set back on and have the 7 Blink code again! SC BLOWN AGIAN!!!!!


3rd Repair Attempt
Once again retest everything like I was starting the repair from the beginning. This is what I found blown I had to order PC461 from China so I had to wait 2 weeks for it to get here. Thinking I must have measured or missed a shorted buffer board I ordered both buffer boards while I waited for the PC461 to get here. I receive the buffers and tested them they look fine as do the originals?



D642 - Shorted
D641 - Shorted
Q661 - Shorted
Q402 - Shorted
Q421 - Shorted
Q422 - Shorted
Q423 - Shorted
D642 - Shorted
Q661 - Shorted
PC461 - Shorted

PC461 came in and I installed it and retested the board everything looks good. Reinstall it in the set and once again tested it without the buffer boards and the jumper installed in SC50. Everything powers up fine no blink codes!!!! Power cycled it several time to make sure it was fine. Reconnect the new buffer boards take some measurements to make sure everything looks good it does so decide to proceed with a power up. BANG LOUD POP and the SC BLOWS AGAIN!!!!

What am I missing could the Panel be bad? I checked it to Chassis ground and do not see any shorts. Could the SS board be causing this? but if that was case would it not blow with the buffers removed and the SC50 jumper installed? Going to rebuild the SC again but before I test it again with the buffers installed I need some help to figure out what is causing it to BLOW.

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

I have a quick question what DMM are you using for these measurements? Once you report back I will let you know why I am asking.

I am currently working on a board out of a 54" TV I will report back my repair after I receive my parts on Monday.

Thanks,
Dean

I have an old fluke 75