Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

[Glitcher]

I've been working on panel for some time and I'm just about to give up on it.

The original problem started with 6 blinks on start. I removed the SC board (TNPA5081) and found the huge bunch of bad parts using tw2005's thread on repairing it. I finally received all the possible parts necessary and replaced everything on the SC board.

I shorted SC50 pins so I can test it without installing the buffer boards. The tv turns on, the PSU makes an odd squealing noise, and hear a click, and it goes to 7 blinks... (still a problem with the sc board?)

Heres the odd thing though, I disconnect the SC board from the PSU and attempt to turn it on, but the PSU, STILL makes that odd squealing noise (could it be a bad PSU??) and it goes back to 6 blinks...

[tw2005]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

Can you list each component you replaced?

When the SC was disconnected was that SC2 and SC20?

Have you rechecked the board to see if the parts replaced are still good?

It should be possible to disconnect SC2,SS11, P35,the 3 white ribbons at the A board and turn it on. Should stay on. Might be helpful for checking the PSU.

let the voltages bleed off before reconnecting SC2,SS11 and P35.

What resistance do you see at SC2 and also at SC20 on the 5V & 15V lines going in there?

[Glitcher]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

I unplugged all the connections you said and the tv stays on, so the psu is probably good (im getting 226V on the PSU to SC2)

All the parts I replaced... so far
Q421 & Q422: DG402RP (x2)
Q401 & Q402: DG502LW (x2)
D482: RFN25
Q452: 45g128
Q621 & Q622
Q660: R5007 <-- (wasn't in any kits so that's new)
Q661: RJP63F4A
Q702
IC773
Q818
IC771
IC501
IC521
D451


I just rechecked all the parts after replacing everything and powered it up, now I have shorts again on parts:
Q661, Q421, dead short on D642 (that's a new one too...), and some of the pins on IC521 seem shorted..

[dcapper]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

I sent mine off to Moduslink tv repair as per tw2005. They charged me $67 to repair it. That included the return shipping. They have a sale on right now until July 4th. 35% off. You'll get your board fixed for under $45. Not even worth the trouble to repair it yourself.

[tw2005]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

I unplugged all the connections you said and the tv stays on, so the psu is probably good (im getting 226V on the PSU to SC2)

All the parts I replaced... so far
Q421 & Q422: DG402RP (x2)
Q401 & Q402: DG502LW (x2)
D482: RFN25
Q452: 45g128
Q621 & Q622
Q660: R5007 <-- (wasn't in any kits so that's new)
Q661: RJP63F4A
Q702
IC773
Q818
IC771
IC501
IC521
D451


I just rechecked all the parts after replacing everything and powered it up, now I have shorts again on parts:
Q661, Q421, dead short on D642 (that's a new one too...), and some of the pins on IC521 seem shorted..

Pins 9,10,13,15,16 will show short to gnd, they're tied together.

Q661, well I would have thought what was replaced would have solved that one providing Q701 was still good. There's also a small 85V diode in that cct too but I can't remember if I replaced any. I have a feeling everytime I did Q661, the inverter ic was killed too, not 100% on that.Check R707 and see if it's still intact.

Q660 i have nothing . maybe go to the schematic and check out the nand gate and bits through to Q660


near IC521, have you checked out nearby components, 100 ohm resistors, theres a SmD diode, and those pnp/npn 5 pin transistors especially Q521

[Glitcher]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

I just bought another TC-P50G20 with the same SC board on 4/10 blinks.
I think I found the problem with my original SC, I thought Q701 was good but its out of spec. It read 1.250 on diode mode while the new part read only 0.602. My second SC board read 1.750 so they are definitely bad.

I decided to quit on my SC board and repair the new one I just got with 4/10 blink. Heres all the parts I found bad
Q621
Q660
Q661
Q421
Q422
Q403
Q402
D482
Q452
Q702
IC773
R421
R422
IC521
IC773
Q701

Parts I replaced just to be safe:
Q818
IC724

After replacing everything I plugged it in, the PSU makes that squealing noise trying to turn on and then clicks and goes to 6 blinks again.. Looking over this SC board only D451 went bad (haven't replaced it yet since it measured in spec) So I replaced it, but this time I tried the second PSU from the 4/10 blink panel.

And it finally works! but this PSU isn't giving that squealing noise. So I'm guessing my problem was something shorted on the PSU, and me not to replacing Q701.

I'm tempted to place the old psu back and confirm but I don't really wanna risk it as it might short something out again on the sc board...

[tw2005]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

I just bought another TC-P50G20 with the same SC board on 4/10 blinks.
I think I found the problem with my original SC, I thought Q701 was good but its out of spec. It read 1.250 on diode mode while the new part read only 0.602. My second SC board read 1.750 so they are definitely bad.

I decided to quit on my SC board and repair the new one I just got with 4/10 blink. Heres all the parts I found bad
Q621
Q660
Q661
Q421
Q422
Q403
Q402
D482
Q452
Q702
IC773
R421
R422
IC521
IC773
Q701

Parts I replaced just to be safe:
Q818
IC724

After replacing everything I plugged it in, the PSU makes that squealing noise trying to turn on and then clicks and goes to 6 blinks again.. Looking over this SC board only D451 went bad (haven't replaced it yet since it measured in spec) So I replaced it, but this time I tried the second PSU from the 4/10 blink panel.

And it finally works! but this PSU isn't giving that squealing noise. So I'm guessing my problem was something shorted on the PSU, and me not to replacing Q701.

I'm tempted to place the old psu back and confirm but I don't really wanna risk it as it might short something out again on the sc board...

So a successful 5081 repair! Finally.

As far as the PSU goes, I think steps in post #2 & 3 proved it was working.

I don't see how a PSU shorts a SC board if the PSU is supplying the power, but I can understand leaving sleeping dogs lay.

I would say not replacing Q701 may have been it. was why I mentioned it again briefly. But i would not rule out Q818 either.

One thing I learned from the last board I did was that it is false economy to 2nd guess sometimes that inverter cct.

As soon as that was good, Q661 stopped blowing, which made it easier to continue fault finding.

[Glitcher]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

Hmm that's true, since the PSU only supplies the 205v to the SC. I'll try to confirm later on when I repair my original SC to be safe.

I ended up just replacing that inverter cct to be safe. I noticed everytime I try to lift up the legs to desolder it, it is extremely brittle and the legs just breaks off easily. I'll try to repairt he original SC again when I get more parts in.

As for the second panel I got, its in pretty bad shape. Dents all over the back and dirt and dust all over along with some scratches, but the screen seems to be intact (at least from looking around it.) I'll probably clean it up IF im able to repair it.
So after repairing the SC board, the 4/10 blink on this went to 8 blinks. If I remember right, 8 blinks means SS board, is that right?

[tw2005]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

Hmm that's true, since the PSU only supplies the 205v to the SC. I'll try to confirm later on when I repair my original SC to be safe.

I ended up just replacing that inverter cct to be safe. I noticed everytime I try to lift up the legs to desolder it, it is extremely brittle and the legs just breaks off easily. I'll try to repairt he original SC again when I get more parts in.

As for the second panel I got, its in pretty bad shape. Dents all over the back and dirt and dust all over along with some scratches, but the screen seems to be intact (at least from looking around it.) I'll probably clean it up IF im able to repair it.
So after repairing the SC board, the 4/10 blink on this went to 8 blinks. If I remember right, 8 blinks means SS board, is that right?

Ok , so you put the just repaired SC into the other TV that you just got which is a mess to check if that was going to fix it and now SOS8?

Maybe it has bad panel?

Monitors
Sustain Drive Circuit and Connection between the SS board and the Panel.

Abnormality of the Sustain drive circuit. Open or loose connection between the SS board and FPCs from the panel (SS61, SS64, SS21, SS24 and SS58). Open or loose connection between connectors C10/C20 Wrong diagnostic by the A board

Order of likelihood
SS
A
Panel
C2 Connections

Do you have the guide?
https://www.badcaps.net/forum/attach...6&d=1394006853

Have not read much on bad SS, guess theres always a first but failed SC/SS together, bit sus.

[tw2005]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

....I ended up just replacing that inverter cct to be safe. I noticed everytime I try to lift up the legs to desolder it, it is extremely brittle and the legs just breaks off easily. I'll try to repairt he original SC again when I get more parts in. .....

I found if I used 2 soldering irons to heat the legs on both sides and pick it up at the same time just using the iron tips as tweezers. Worked for most situations.

I dare say the board will be similar in damage as my last one, so you may have to look at that long list. Once you have a good board, helps to compare readings but still tricky.

[Glitcher]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

I had some suspicion of a bad panel since its in such bad shape so I left the buffer connections disconnected when testing. But since the buffers weren't connected, it shouldn't be able to detect a panel error? Yet it still gave 8 blinks.

I may try swapping the SS board and A board over and see what happens. It shouldn't be able to damage anything as least that's what I'm thinking.

The original problem was 4 blinks or sometimes 10 blinks (faulty SC board now fixed). after repairing that its now 8 blinks. I was wondering how do these error codes go in order if there are more than 1 error codes?

[tw2005]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

I had some suspicion of a bad panel since its in such bad shape so I left the buffer connections disconnected when testing. But since the buffers weren't connected, it shouldn't be able to detect a panel error? Yet it still gave 8 blinks.

I may try swapping the SS board and A board over and see what happens. It shouldn't be able to damage anything as least that's what I'm thinking.

The original problem was 4 blinks or sometimes 10 blinks (faulty SC board now fixed). after repairing that its now 8 blinks. I was wondering how do these error codes go in order if there are more than 1 error codes?

Not sure But i guess you'd have to work out the startup sequence.

A dead short on the vsus would be fairly early on, I know SOS1 is just before it produces a picture.

that X20 I had , did not reveal SOS1 until 4 blink was cleared.

Well you know the trick of proving the PSU and A board. disconnect SC2,SS11, 3 white ribbons, p35 and turn on. If no SOS then you know it's not a false trigger on the A-board.

I think you can disconnect the SS without a SOS too. Will have to have a read.

[tw2005]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

Slide 61, SS11 removed, should turn on. Same for SS23. Flow chart to follow too, page before.

[Glitcher]

Re: Panasonic TC-50G20 6 blinks (Bad SC TNPA5081)

Looks like it seems to be a bad panel, well at least a bad driver on the bottom tabs. I disconnected the c board from the x-main and the tv turned on and stayed on. I tried swapping the c boards from the good panel to this one and still 8 blinks.

Doing some testing on the working panel, it seems it will only shoot the 8 blink error code if one of the tab connections to the c-board is disconnected or just bad.

I'll probably be parting this set out, I tested all the boards and they are still working.