Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Also shopjimmy sells this kit which includes an IC, resistors, diodes and IGBT's. Does anyone knows which IC needs to be replaced if it's bad ? So far I've checked all resistors and diode's and none of them are short or open.

http://www.shopjimmy.com/panasonic-t...repair-kit.htm

[Alastair E]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

You'll have to trace back the Gate connections of each dead IGBT to its driver stages and replace the chips transistors you find in each one....

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Thank you Alastair for your reply, so I did checked all the driver chips and none of them are shorted. There are some videos on youtube on how to check bad driver chips, which is what I followed. To check the driver chips I used the continuity from chips to each ribbon cable and didn't find any short

I know if the screen has any cracks then that will cause the SC board to fail too but in my case I don't have any cracks on screen.

[Alastair E]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Not a very reliable way to check the driver-chips, --Not sure what you mean checked for continuity to the ribbon-cables--sounds like you are checking Buffer-Chips to the panel-tabs.

What I mean is the tiny 8 legged chips that Drive The IGBT's and the 5 legged transistor pairs --NOT the big square chips that drive the panel (buffers)

These parts are Small, connected via a 5 ohm surface-mount resistor to the 'G' terminal of the dead/killed IGBTs you replaced.......

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Are you talking about these chips ?

http://i44.photobucket.com/albums/f1...psee7bf18e.jpg

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

If you do then the resistance from output of one of the chip to gate of IGBT is somewhere around 6 mega ohms, not sure if it's suppose to be that big.

[Alastair E]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

yes--those are the sort of chips the drivers are. somtimes--theres a 5 legged dual-transistor between the chip and the igbt--depends on what part of the circuit its in.

Only way to be certain with these buggers is to replace 'em --can not tell by cold checks in a lot of cases whether the driver chip is good --just with a meter.

--Most times, the chips will survive--but in --they say 20% of the time, driver-chips-- obviously in your case, as the igbts instantly failed at switch-on.

--If you imagine the y-sus (SN board) as a three legged H-Bridge of igbts, if one is held on by faulty-driver, then three or more of the 6 including the one held on--will die....
See the irf apps note in my sig for details as to roughly how these things are wired up and why if one goes--loads go!

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Thank you I'm picking up a dead TC-P50S30 TV with cracked screen this weekend and going to swap the driver chips. According to service manuals the driver chips are same on both TV's.

And will also replace not only failed IGBT's but also which are working too. I just want to rule out the possibility of bad IGBT which may be faulty but not showing short on my DMM.

I'll post my reply with my findings in next few days

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

So here's an update.

I replaced all 4 driver IC's to IGBT as well as all IGBT with new ones from eBay. Tested the SC with putting a jumper to SC50. Powered the set on, saw green leds on SC and SS boards. Was very happy to see both board alive and no blinks

Powered off the set, put back the white connectors to buffer boards as well as ground screws, powered back the set. Heard buzzing sound from SC board and now I'm seeing 6 blinks instead of 7 blinks. However I don't get any short at main connector SC2 but I do see one of the IGBT 30F131 which is closer to SD (buffer) board is now showing short.

Does that means that my SD board is short ? If the SD board is indeed short how do I find the bad driver IC ? Cause I checked the continuity from one of the source pin to ribbon connector but couldn't find one.

[freakaftr8]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Here's the way I test the Su And SD boards got the same TV in for repair today. Pull Su And sd Boards off SC board use black probe to the screw lug of the SU or SD then red probe on diode check continuity mode run it across the pins on the ribbon connectors if you get a beep on any of those connectors follow the leads to the IC chip that is bad. If you run a bad board on the brand new repaired sc it will blow it right away.

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Thank a lot for you reply, so I went ahead and followed the procedure of testing the buffer chips on SU and SD boards.

And while doing the diode test I found one pin from all ribbon connector dead short (I think it's pin 14 or 15 from bottom of each connector). So the question is that normal or does all buffer chips are bad ?

Cause if the buffer chips are indeed bad then that explains why my SC board blew right away after connecting the SD & SU boards. Also while testing all transistors again on SC board yesterday I found RJP63G4 dead short, which could explain the buzzing or humming noise from SC board. I'm going to order RJP63G4 and see if I can get the set running without SU & SD boards connected.

[tw2005]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

It's a general rule to check buffers for shorts beacause they will kill the SC. Any shorted output pin is bad but since you had the SC running with the bypass and then buzzing/failure hooked up to the buffer boards that sounds conclusive.

I do wonder if just Q661 was damaged or other parts .

Guide for ST30 has a procedure for buffers if you wanted to try it.

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Thanks a lot, the troubleshooting guide indeed is very helpful and I wish I had this reference manual earlier.

Yes I have a same feeling that it's just Q661 at fault and I've the parts arriving tomorrow. Will post with my findings.

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Good evening guys, Here's an update.

Today I received RJP63G4 and after putting everything back I did the resistance tests for SU & SD boards before turning the TV as per the troubleshooting manual. The resistance at both test points were in mega ohms, which made be think that my SU/SD boards are good.

Shorted SC50, removed the white connectors to SU/SD board and plugged the TV to mains and to my surprise the TV started without any hiccups. After putting all the connectors and screws I tested one more time and I got a display.

First thing I did was to update the firmware cause I've been reading and someone mentioned to update the firmware on these 2011 models. So the firmware update was successful, TV rebooted after the update and I wanted to see if the SC board stays alive for few minutes, so I plugged my laptop and started a movie, 5 min after starting the movie TV went back to 7 blinks. Didn't hear any pop or humming noise as last time. Found just one IGBT 30F131 short.

So something else is causing the SC board to fail, either I received defective lot of IGBT's or something else is causing these IGBT's to blow. Any ideas ?

[tw2005]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Good evening guys, Here's an update.

Today I received RJP63G4 and after putting everything back I did the resistance tests for SU & SD boards before turning the TV as per the troubleshooting manual. The resistance at both test points were in mega ohms, which made be think that my SU/SD boards are good.

Shorted SC50, removed the white connectors to SU/SD board and plugged the TV to mains and to my surprise the TV started without any hiccups. After putting all the connectors and screws I tested one more time and I got a display.

First thing I did was to update the firmware cause I've been reading and someone mentioned to update the firmware on these 2011 models. So the firmware update was successful, TV rebooted after the update and I wanted to see if the SC board stays alive for few minutes, so I plugged my laptop and started a movie, 5 min after starting the movie TV went back to 7 blinks. Didn't hear any pop or humming noise as last time. Found just one IGBT 30F131 short.

So something else is causing the SC board to fail, either I received defective lot of IGBT's or something else is causing these IGBT's to blow. Any ideas ?

Ouch, Moments like this, boy i take deep breaths. So close. At least I'd assume the buffers are ok.

So the 30f131 is that replaced blown or original? Anything else dead? Is that IGBT paired with others? I read a story of a guy removing a dead one and it's pair carried the load for a quick test and turned on ok. Not something I'd be brave on but often they may have 2 or 3 in parallel sharing the output so theorectically would work, maybe not drive the panel like this but I'm just guessing. Not an engineer on this.

Is it the 50GT30 you have? i have a Brazilian manual with good schematics, maybe looking at that would hel and trace the cct to see how everything relates>

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Ouch, Moments like this, boy i take deep breaths. So close. At least I'd assume the buffers are ok.

So the 30f131 is that replaced blown or original? Anything else dead? Is that IGBT paired with others? I read a story of a guy removing a dead one and it's pair carried the load for a quick test and turned on ok. Not something I'd be brave on but often they may have 2 or 3 in parallel sharing the output so theorectically would work, maybe not drive the panel like this but I'm just guessing. Not an engineer on this.

Is it the 50GT30 you have? i have a Brazilian manual with good schematics, maybe looking at that would hel and trace the cct to see how everything relates>

Thanks for your reply tw, Yes I do have 50gt30 model. So here's what I did after getting the 7 blinks, before removing the SC board I found just Q401 short. So I removed the SC board from the TV and started checking all the test points and to my surprise I found none of the IGBT's were short. So I checked first SU board for short and didn't any connutiny however on the SD board I found one buffer chip short.

So I need all of guys opinion as to whether I should replace the SD board or just replace the dead chip ? I'm good at soldering SMD chips but to get the black residue out is very painful. If I decided to just replace the dead chip what do you guys do to remove the residue ?

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

One interesting and unusual thing I noticed after removing SD board was there was a think layer of dust accumulated on the ribbon cables at each connector. The dust was mostly on the gold plated pins, so that could explain why my SC board kept on blowing all the time as soon as I connected SU/SD board.

[tw2005]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Thanks for your reply tw, Yes I do have 50gt30 model. So here's what I did after getting the 7 blinks, before removing the SC board I found just Q401 short. So I removed the SC board from the TV and started checking all the test points and to my surprise I found none of the IGBT's were short. So I checked first SU board for short and didn't any connutiny however on the SD board I found one buffer chip short.

So I need all of guys opinion as to whether I should replace the SD board or just replace the dead chip ? I'm good at soldering SMD chips but to get the black residue out is very painful. If I decided to just replace the dead chip what do you guys do to remove the residue ?

If you're good at it maybe have a go, I'm not but i can confirm that the grey silicone is under that ic sticking it good and there's not solder pad. That's if they are similar to the G25/25 buffer Ics. I destroyed the tracks, the adhesive was the main cause. I tried cutting the pins along the body of the IC and then it took afar bit of force to twist the ic and break it free. heat may help but my knowledge is nil for this level of repair. I then attempted to desolder the legs left with an iro nbut not all the silicone was removed and the tracks were like paper.

It was a dead board, one of several which i was thinking of making a project to repair but I'm passing too hard for me.

If there is a short on that buffer, for sure that's probably it for blowing the SC. I'd go down the pathe of finding a board. I don't think those ICs are too cheap either if you can get them which most likely be china. AFAIK panasonic don't regard the buffer boards as repairable so I don't think you can get those direct through them.

[myfastgti]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

Thanks tw. I did found a seller from China selling these chips for $5 ea, but like you mentioned it's better to replace the board rather than removing the adhesive and risking to rip off the tracks. I'll go ahead and order new SD board.

One last question I would like ask is, if you've been seeing vertical black lines on the front display of screen mostly caused by improperly seated brown ribbon cables from SU/SD board, then would that cause the buffer chip to blow ?

[tw2005]

Re: Panasonic Plasma TC-P50GT30 7 blinks SC board shorted

VERTICAL LINES, generally faulty panel. I associate horizontal with the sd/su boards?