Panasonic TCP50G20 4 Blinks

[Borghi]

I am trying to troubleshoot my TCP50G20. It will not power on and has a fault light blinking 4 times. I have read this is probably the P board, but MAY be the A board. When I turn on the TV, the relay clicks and then about 20 seconds later they click again. At the second click, the 5V on the goes dead. It seems like there is a protection circuit shutting down the power. Any ideas on how to further troubleshoot this problem? This is my first time posting here, and any help is very much appreciated!

[Malachi]

Re: Panasonic TCP50G20 4 Blinks

According to the service manual 4 blinks is P-board sos.
http://manualmachine.com/download.ph...948e7dc3f186ba

[tw2005]

Re: Panasonic TCP50G20 4 Blinks

I am trying to troubleshoot my TCP50G20. It will not power on and has a fault light blinking 4 times. I have read this is probably the P board, but MAY be the A board. When I turn on the TV, the relay clicks and then about 20 seconds later they click again. At the second click, the 5V on the goes dead. It seems like there is a protection circuit shutting down the power. Any ideas on how to further troubleshoot this problem? This is my first time posting here, and any help is very much appreciated!

Check out the SC board and see if SC2 is shorted or disconnect SC2 and turn on and if the 4 blink changes the SC board is shorted.

Sure if you do a search on the model, 4 blinks or tnpa5081 you should have plenty of reading.

According to the service manual 4 blinks is P-board sos.
http://manualmachine.com/download.ph...948e7dc3f186ba

yes it is, just that it's often something connected to it that drags Vsus down and triggers this.

[ljintexas]

Re: Panasonic TCP50G20 4 Blinks

Mine was the SC board that was taken down by shorted SD/SU buffer boards..and I had four blinks. Do the testing outlined in the manual for the SD/SU boards..if either one fails, chances are it took the SC board. This will cause the voltage drop to the A board and appear to be an A board failure.
I replaced SC,SD,SU and mine is still running like a new one..that was over six months ago. My $.02.

LJ

[Borghi]

Re: Panasonic TCP50G20 4 Blinks

If I disconnect the SC board and apply power (plug in power cord and press on/off button), the blinks go to 7. I put an ohmmeter across SC2 with no power applied and I am NOT picking up a dead short. There is some resistance there. Where do I go from here??

[Diah]

Re: Panasonic TCP50G20 4 Blinks

from my experiences with Panasonic, it suffer always from bad SMD soldering . especially the sockets of the Backlight strips, 2 time i found this issue and the socket was out from the plate and make short contact with chassis, keep this in mind too. .

[Alastair E]

Re: Panasonic TCP50G20 4 Blinks

from my experiences with Panasonic, it suffer always from bad SMD soldering . especially the sockets of the Backlight strips, 2 time i found this issue and the socket was out from the plate and make short contact with chassis, keep this in mind too. .

The set in this thread--Is a 'Proper' TV Its a Plasma.....

--ie, NO daft backlight boards.

Soldering of the parts of SC etc, is IME with these sets is pretty good, as Panasonic make their own, ie, not some cruddy third-party Backlight/Display assembly made by gawd-knows who, as is the case with all the usual LCD Rubbish around....

IF there's a resistance on SC2, Check Q661 for S/C. Pretty sure it'll be short plus a whole lot more as well...

[Borghi]

Re: Panasonic TCP50G20 4 Blinks

I went back and followed all of the troubleshooting steps outlined in the troubleshooting manual provided by Malachi (thanks for the manual!). There were no shorts found looking at the Vsus, Vda, or P15V using the test methods on Slide 8 of the manual. From here, I went to Slide 27 and did the steps there. Unplugged SC 20 and had 4 blinks. Tested voltage at pin 9 of P7 with TV turned on and had 3.1 V. According to the flowchart I need to replace the P board. Does everyone agree? Anyone see something I might have missed?

Has anyone been successful in repairing the P board??? Any tips and advice are appreciated!!!

[Alastair E]

Re: Panasonic TCP50G20 4 Blinks

Please check Q661 on SC board--Confirm it Isnt S/C before blaming the PSU.

Rare for a Panasonic PSU to fail in that way. They have been known to go where they are completely dead--no lights, no Stdby --nothing.

Due to the way the A board interprets faults--the flow-chart can have you chasing your tail and blaming the wrong boards. --Just the way they are....

[tw2005]

Re: Panasonic TCP50G20 4 Blinks

I went back and followed all of the troubleshooting steps outlined in the troubleshooting manual provided by Malachi (thanks for the manual!). There were no shorts found looking at the Vsus, Vda, or P15V using the test methods on Slide 8 of the manual. From here, I went to Slide 27 and did the steps there. Unplugged SC 20 and had 4 blinks. Tested voltage at pin 9 of P7 with TV turned on and had 3.1 V. According to the flowchart I need to replace the P board. Does everyone agree? Anyone see something I might have missed?

Has anyone been successful in repairing the P board??? Any tips and advice are appreciated!!!

Already from what you have said the SC board is causing this. At SC2 what resistance do you have then? Keep in mind 200v gets sent to that so it won't have to be 0 ohms to trigger 4 blinks.

Think about this logically, you removed Sc2, 4 blinks cleared. You remove SC20 but put Sc2 back, 4 blinks.

Vsus is overloaded at SC2

So here's another test for you to try.

TV off, disconnect sc2, P35, ss11 and the 3 white ribbons at the A board.

Turn the TV on, it should startup and stay on with no error blink, turn it off then do not connect P2,p35 or ss11 for more than 5 mins so the vltage can drop off those otherwise you can spike the panel that'll be the end of it.

If it does this then tis proves the P and A boards have no errors

Only run it long enough to get a result. You could at this point check the voltages present. If it runs unloaded for more than 30sec it will go 4 blink but that is normal.

[Borghi]

Re: Panasonic TCP50G20 4 Blinks

I am really impressed with the knowledge and helpfulness of the people in this forum. This is my first time attempting a TV repair, and your help has been invaluable! I couldn't find Q661 on the SC board, so I went back to the beginning and did all of the procedures in the manual again. I noticed that one of the leads on my meter was not fully inserted so I thought I'd better recheck everything.

In checking for shorts on Vsus, P15V and Vda, I found a dead short on the P15V (Connector P11/Brown pin#4). I then went to the detailed procedure on Slide 14 and this testing confirmed "replace SC board".

I then conducted tw2005's test where I unplugged sc2, P35, ss11 and three white ribbons on the A board. The TV turned on and stayed on with no error blink. I shut it off manually after 25 seconds.

So now I am at the point where it appears to be confirmed that the SC board has a defect and the P board is OK. Where does the group recommend I proceed from here??

[Alastair E]

Re: Panasonic TCP50G20 4 Blinks

Depending on your experience, Rebuild or Replace/Get SC Repaired....

--There's a number of very small parts such as Q701, Q702, IC773 etc that will need changing along with a number of the heatsink mounted devices, and many other of the surface-mount parts will need testing.

Do you have the tools and think you can handle such work....?

[Borghi]

Re: Panasonic TCP50G20 4 Blinks

I don't think I would attempt a repair myself, but I will study it further. If I don't do the repair, I'll have to find someone to do it. Are there any recommended vendors for doing board repairs? If I have the SC fixed, will there be other boards that need attention, or is it typically limited to the SC board?

[tw2005]

Re: Panasonic TCP50G20 4 Blinks

I don't think I would attempt a repair myself, but I will study it further. If I don't do the repair, I'll have to find someone to do it. Are there any recommended vendors for doing board repairs? If I have the SC fixed, will there be other boards that need attention, or is it typically limited to the SC board?

http://www.ptselectronicsinc.com/

You need to follow this up with the sd/su board tests as well. Don't assume just because you found the SC bad that the others are oK. All 3 have the potential to go out together and a bad buffer set can take out a new working SC!

[Borghi]

Re: Panasonic TCP50G20 4 Blinks

Do you mean the resistance tests in the troubleshooting manual?

[tw2005]

Re: Panasonic TCP50G20 4 Blinks

Do you mean the resistance tests in the troubleshooting manual?

yep, in the g20,25 training guide there's a section dedicated to it.

[Borghi]

Re: Panasonic TCP50G20 4 Blinks

I had to take some time out to do some other chores, back at it again and I am more confused than ever. Before I start spending money on board repair or replacement or repair, I decided to go back to step 1 and do one more check. In doing so, I found out that I screwed up when I did the testing the second time. When testing for short or low resistance on Vsus, Vda, and P15 V (slide 8), I checked the P11/Brown at the WRONG CONNECTOR. I tested it at connector P2 instead of P11. I was doing it from memory and messed up. Long story short, I tested resistance at P11 and P35 and got readings of OVER 1K at each point (NO SHORT CIRCUITS FOUND). I then went to the troubleshooting flowchart on slide 27 and disconnected SC 20 then turned power on. TV showed 4 blinks again. I unplugged the TV and got ready to measure voltage at pin 9 of connector P7. Turned TV on and measured 3.1V. At that stage the flowchart indicates "Replace P Board". I am 100% certain of my test results this time. Am I now certain that the P Board is what I need to replace?????

[Alastair E]

Re: Panasonic TCP50G20 4 Blinks

Check all the heatsink mounted IGBT's for shorts.

Sure you'll find a few S/C....

As I said earlier--Following the flow-charts will have you chasing your tail. Do some proper resistance checks on the SC board of the heatsink mounted parts...

We have already determined earler Your SC Board Is Stuffed!! Forget the P and A boards for now--your tests prove those OK.

[Borghi]

Re: Panasonic TCP50G20 4 Blinks

Check all the heatsink mounted IGBT's for shorts.

Sure you'll find a few S/C....

As I said earlier--Following the flow-charts will have you chasing your tail. Do some proper resistance checks on the SC board of the heatsink mounted parts...

We have already determined earler Your SC Board Is Stuffed!! Forget the P and A boards for now--your tests prove those OK.

I did all of the resistance measurements on page 43 & 44 of the manual and did NOT pick up any shorts. Am I supposed to do anything else?