The actual cause are loose screws. Why did they get loose? Because of the solder on the contacts. Solder is soft and flows under pressure. Why is this troublesome? Some screws and their contact pads conduct a lot of current into the metal panel chassis. When they become loose, the contact resistance increases and sparking occurs. This in turn leads to very high current peaks, which eventually kills (shorts) a diode. It is also possible that the increased resistance causes the mounting area to heat up and that kills a diode. This diode connects six transistors and another diode and those die immediately.
The next image shows the troubled screw position in close-up. It takes the full current from the DAF30 diode to the panel chassis ground. Other screws, which I'll show you below, pick up the current and from there it flows back to the power supply. Notice how the legs of the diode are discolored through heat! This one got enormously hot:
The mounting hole backside under the microscope. We see blackened, burnt solder:
And this is what a mounting point looks like:
As long as the screws stay under tension, the contact to the chassis will be good.
In the 60 series, Panasonic has learned from the screw disaster. This is an image from a 55STW60. No solder on the holes and screws with spring washers!
They also finally stopped using SMD power transistors and returned to decent heatsinks. Who needs silly super-flat TVs, anyway? I think those scan boards are built for eternity - maybe, provided the capacitors, which get all the heat from below, are holding up well.
In the next image, I marked the other screws, whose holes also had burn marks. The two on the top pick up the current from the chassis, which enters through the screw in the center. You see the already repaired board with my choice of transistors and diodes (see this post). Other screws have a proper bracket on the board or don't carry much current. There, the contacts looked ok.
In the 60 series, Panasonic has learned from the screw disaster. This is an image from a 55STW60. No solder on the holes and screws with spring washers!
They also finally stopped using SMD power transistors and returned to decent heatsinks. Who needs silly super-flat TVs, anyway? I think those scan boards are built for eternity - maybe, provided the capacitors, which get all the heat from below, are holding up well.
In the next image, I marked the other screws, whose holes also had burn marks. The two on the top pick up the current from the chassis, which enters through the screw in the center. You see the already repaired board with my choice of transistors and diodes (see this post). Other screws have a proper bracket on the board or don't carry much current. There, the contacts looked ok.
And here is the section of the circuit where you can see all the affected high-power parts in one glance. The DAF30 diode is marked yellow. The diode and three transistors to the left and the three transistors to the right next to the troubled diode are all shorted when disaster strikes.
From 7 blinks to 6 blinks
6 blinks indicate a problem with the MIR voltage, the energy recovery voltage, which builds up across the blue C631. It must stay in a corridor around 120V.
Strangely, a driver transistor plus its control chip die, even though they are not responsible for any of the shorted power transistors. Q441 is still ok, yet those two are dead. I wonder why, but I have observed this twice already, only in 42 inch models though.
Broken IGBT (energy recovery L section)
The boards I have repaired also had a less obvious failure in Q451, a DG302 transistor. It has no dead short, but in diode test mode, it will leak between collector and gate and show a break-through voltage on the multimeter. It may not have this fault at the beginning and develop it once the other defects are repaired and you switch the device on for the first time! But don't worry, it will not destroy any other parts. It is best to routinely replace it.
See also below where I describe how to debug the recovery section.
How to repair this defect properly
- Replace all broken components
- Remove all solder on both sides of all screw mounting holes. Only apply a very thin and flat(!) layer of solder. It helps making a good contact.
- Clean the mounting points on the panel chassis from all black residue.
- For the screw next to the DAF30 diode and the two on the top, replace the original screws with ones with a spring washer. Make sure they are not too long, otherwise you will drill into the panel! The screws will not loosen much once the solder is gone, but for the critical ones I want extra safety.
Debugging the 6 blinks of the energy recovery circuit
Through my own stupidity I damaged an already repaired board and spent hours trying to find the reason for the 6 blinks. The device started, the green LED on the SN board briefly came on and then it immediately shut down. Not enough time to take measurements with a voltmeter. A not 100% working driver transistor was the culprit. Along the way I learned a lot about the circuit.
Get the manual for the TC-42GT30 from elektrotanya.com. This manual is top quality with zoom-able schematics. Page 69, chapter 12.27 SN1 Board Schematic Diagram. I have another for the TX-42 with pixelated graphics, where you can't read the part numbers.
The recovery voltage can be measured across C631. It should be around 120V. The protection activates below 36V and above 157V. The polarity is not important, just focus on the amount.
A multimeter in MIN-MAX mode may not be fast enough to catch the max amount. I used a digital storage oscilloscope in roll mode with 1ms time base. It showed the ramp-up of the voltage beautifully. However, this is not required, because if the protection circuit fires, there are only two possible cases, which a quick multimeter can detect in MIN-MAX mode:
If the voltage is missing, the recovery L section is not working. Most likely, Q451 has a problem as described above. Mine never had a full short. If it has, also replace Q551 and IC522.
If the amount is too high, the recovery H section is not working. Strangely, Q441 does not die, but its companions Q531 and IC502. This is a total mystery to me.
Spare parts
In THIS BLOG POST I talk about possible replacement for discontinued parts. I am trying my luck with the FGD4536 for all the power transistors, including the DG302.
this is a really good blog,actual repair demonstration instead of just teasing,i've re-read everything just out of curiosity.
ReplyDeleteI wanted to ask if you can help me to fix my plasma TV?it's a Life's Good 50PQ30R,it wasn't even powering the panel,Y-SUS was destroyed,now i've fixed some fried resistors,cold soldering,bought a replacement Z-SUS for nothing(mine is fine),now it displays a very bad image,it's like missing the gamma,the brightness options only makes the black turn into white(setting it to 0 it gets closer to normal),color temperature,black levels and energy saving influences on nothing,messing with the contrast is almost the same as brightness,i still think it's an y-sus problem,also the coil on it just won't shut up,it's noise frequency increases evenly with the brightness setting,z-sus is quiet.
http://i.imgur.com/Jdpb34k.jpg this is how the gray looks
http://i.imgur.com/zdWGjJp.jpg using the same image as you
Hi, I don't fully understand what the defects were and what you have done so far. The Y-Sus was destroyed and you replaced it or were the fried resistors on the Y-Sus? I mean, resistors don't fry for fun, something pulled too much current through them. Have you measured the Vs and the other base voltages and compared them to the reference value (sticker on the panel)?
DeleteA reddish tint normally points to the Z-Sus, because the pixel are not properly discharged. But we can rule that out. Generally, the waveform generated by the Y-Sus scan and/or sustain circuit seems to be broken. I have no experience with this particular device, my speciality are Panasonics.
As the image is basically present, I would not assume a problem with semiconductors or control ICs. It rather looks like a problem with passive components. Are the large capacitors on the Y-sus okay (ESR, capacity)? But then again, why did the resistors die?
I can only suggest to rigorously test critical components to try to get some lead on a defect.
Thanks for the reply!I'm exaustingly examining the y-sus again,will test individually 2 ICs,their heatsink doesn't even heat up.All the voltages are calibrated,i'll get some way to measure the caps,they at least look ok,i managed to damage even my multimeter that could do that.Also separated the text like you did,makes it more readable.
ReplyDeleteGot the TV for cheap,the defects were that it wouldn't power the screen,someone had already messed with the y-sus back in 2012(as said a sticker on the back) and broke some trails,horrible repairs all around,but it is really easy to damage the PCB,so that's why i don't want to go dessoldering everything.
To "fix" it was only the resistors on both z-sus and y-sus(i think heat killed them),but a broken pin on the VSCAN IGBT(now it's fixed) made the panel only blink and shut down,i thought it was the z-sus and bought another one,today i've put back the original,no changes.Don't want to bore you with all the little details that i've gone through to get here,it is a lot.
I'm starting to grow quite a LG plasma collection,this 50PQ30R,a 42PQ30R and a 42PG60D,maybe one day i'll become an LG expert haha.
Could you pleasee help me with this?>The 42PG60D has 4 ICs shorted on the Y-SUS,all of them GT45F123,could i replace them with GT45F122(the ones at the 50PQ30R other Z-SUS)?the Z-SUS signal is controlled by them.The only difference on the datasheet is the 45F122 "VCE sat" voltage is higher,2.7V VS 2.4V,they all handle the same max voltage,current and power dissipation.
Oh dear, TVs with unknown history are kind of a lottery. Maybe it is best to just get a used, working Y-Sus. Who knows what damage the unprofessional repair has done to it.
DeleteAbout the IGBT Transistors (they are not ICs): I'm not familiar with this specific types. My experience is that at least Panasonic Plasmas run fine with parts, which closely match the spec of the original. No 100% match required. LG must have had their reason to use an F123 instead of F122, which doesn't mean that it is absolutely necessary.
When the replacement stays in a healthy temperature range and the device shows no other symptoms, it could be ok.
Note however, that shorted IGBT transistors may have killed their smaller driver transistors and the control IC, too. The drivers are easy to measure, they are ordinary transistors. If they are good, you got lucky. If not, well, you need some luck. Otherwise the repair gets a substantially more difficult and expensive.
You planned to move the IGBTs from the spare Z-Sus to the Y-Sus? That's ok. I just wanted to warn you about buying those from China. I never got a single genuine IGBT from there. There are alternatives from DigiKey or Mouser, if you need some.
Hi,
ReplyDeleteI don't know the difference between a GTF32 and a GT30, but I assume they are mostly the same.
According to the service manuals, the 6 blink is related to the SN board. The 8 blink mainly indicates a problem with the SS, but it can also mean an interrupted connection between SN and A. So that makes total sense.
So, you need to do something about your SN board. If you are not going into the component level like I described in this post, you will have to find a replacement.
Hey Hermann,updating and hopefully ENDING my status.
ReplyDeleteOn the 42pg60d,i got four 30F124 from my original 50pq30r z-sus,and replaced the shorted 45F123 from the y-sus,still nothing would work,then checking the resistors i found an open 1.2 OHM,replaced and with the t-con auto-gen the screen came alive!i left the tv testing the patterns and discovered 2 channel logo burn-ins,got a little sad,after 10 min on the red and blue test a vertical line showed up in the middle of the screen,when it was red the line was pink and blue it was red,got really sad,at least they only appeared when the whole screen was those colors,now i have to fix the signal board,no video no audio,i got lucky,the service manual is really crap for anything but that.
50PQ30R almost fixed,i just replaced the whole y-sus board for real cheap!i can sell the defective one for almost the price i paid,but now a problem still remains,this tv is autisticly changing the brightness intensity(energy saving),like randomly,now it's stuck to the lowest,this also happened with the old board and both z-sus,the brightness option changes nothing like before,do you think t-con is to blame?
Oops,there were 2 broken out SMD capacitors at the t-con,that happened when i carelessly whispered the power supply out without holding it,it fell at the t-con and broke them,fixed that but seems like it was working fine even without them,the i did the auto-gen test and the brightness was at its max working fine,it was the main board option "intelligent sensor"(stupid as hell) was always active even if i manually input anything,so i restored the initial settings and the tv is working like a wonder.
ReplyDelete50PQ30R and 42PQ30R have the same amount of pixels in the display(1366x768),but this one is so much better,the 42 inch i can barely read any text.
Planning on buying a P50B11G,since you are a panasonic expert,is it a smart buy for a considered cheap price?
I cannot say anything about the B11G. My experience is limited to the 20, 30 and 50 full HD series. As I am reselling the repaired devices, the older models are not attractive for me.
ReplyDeletePffff , i spent so many hours on the 6 blink error. I had symptoms where the green led on the SC board immediately lights up when power is applied. In the end it was indeed a bad DG302 that did not read short.
ReplyDeleteThese are still great tv's!!
It's time for OLED to repair Hermann
Yeah, that half-fried DG302 is really nasty.
DeleteI love my 55VT30 to bits! Once a 7 blink patient, now in my living room :-) The colors are so close to how I experience them in a good cinema. Looking at LED TV images makes me sad.
I don't see any broken OLEDs on eBay/classifieds, yet. The tendency with TVs in general seems to be dead mainboards or panels. It is becoming increasingly difficult.
I agree with you! Unless you got a OLED , there is no tv that can display these deep colors. Im still searching for a defective VT or ZT60. Only difference is the mainboard.
ReplyDeleteHi Hermann,
ReplyDeletein my P42ST30E I changed all the components shown in this photo
https://drive.google.com/open?id=0B2Bix8JyAB_IWkgwVzhtdFhKdnM
At first, I hadn't changed IC502 and Q531 and got 6 LED blinking.
Then I changed IC502 and Q531, as you said recovery H section, but still have 6 LED blinking.
So I tested the recovery voltage across C631 and found peaks more than 120 V (my tester is very slow, so I assume the real peak may be higher)
As I said, I have already substituted IC502 and Q531, and Q441 doesn't seem to have obvious shorts...
What do you suggest? Replace Q441 with an FDG4638 or to replace IC502 and Q531 again?
Q441 ist most likely undamaged. I never had to replace it. If the recovery voltage is not missing, it can only be the fault of the recovery high section. The 6 blink can only have those two reasons and I follow this logic strictly.
DeleteI also had to replace the control chip and the driver transistor once again because I damaged them while soldering (I think). That took me some time to find out!
Also, really check the soldering on the little chip very thoroughly through a looking glass.
DeleteCheck resistor R507 - 22 Om. In my case resistant was about 56 Om. After new resistor no problems with IGBT
DeleteHello,
ReplyDeleteHow can I test every Transistors / Mofsets.
I have unsoldered the 2 legs of most of them . With a multimeter I check the 2 legs together and each legs with the top pin. What Am I supposed to find out.
I think I must not have continuity betweek each pins.
Can you confirm ?
Thank you !
For quick defect test, this will do the job. When the transistors die, they go short.
ReplyDeleteThank You !
DeleteI hope the driver and the controller are not fried. I should have the 6 blinks issue if they are...
Some mofsets seem to have survived, do you think I should change all of them ?
That's hard to tell. If they have no short, they should be fine.
DeleteThis comment has been removed by the author.
DeleteHi Hermann!
ReplyDeleteI am struggling with P42GT30. Tried to repair the TNPA5330, but I got at the end 6 blinks with zero volt across C931. Changed Q441 and Q451 and their driver ICs, same result. Then I got another TNPA5330 never touched before with 7 blinks. I changed usual IGBTs, checked gate resistors, and I got 6 blinks with 170 V across C931. Then I changed driver ICs (Q441 is not shorted), then I got zero volt across C931!! Then I changed Q451, I checked driver IC Q551 and it seems ok. But no results: 6 blinks. I also changed A board, no results.. Any idea?? Last thing is that I am using a bulb in series with Vsus. Vsus raises to about 205V during green power led blinking, then 215V for a short moment before red 6 blinks. But I do not think it is affecting..or not?
I think you got confused. If the voltage across C631 is missing, you have to fix Q551 & IC522. Your recovery section is still not ok. If you follow my guide exactly and provided you don't damage parts or have bad parts in the first place, it will work eventually.
DeleteHi Hermann! A short update. Yes, I intended C631, not C691. The Q551 seems ok. I also have checked voltages: at Q451 collector I read 150V from chassis, and at Q441 collector 188V. Then across C631 I have 36-38 V. This in the first 3 - 4 seconds from switch on. During this time gates of Q441 and Q451 are at zero volt. Then I can read 13,5V at gates for a short while, these IGBTs do switch (it should mean that IGBTs and drivers are ok) but after this short while SOS6 goes up and 6 blinks occur. Unfortunately I do not have a working tnpa5330 to compare these voltages and check where they are not ok. I have also checked that pin7 of IC522 and IC502 rise to 14V when pin2 of these ICs rise to 5V, this in the short while before SOS6 on. Any ideas? I tested them with a "normal" tester with the switch on "DC voltage". What can I do now?
ReplyDeleteI have never done the measurements you described, so I cannot comment on that. I had to use an oscilloscope to debug the recovery circuit and its protection mechanism. A multimeter is not quick enough.
DeleteDo you have any suggestions?
DeleteCan you tell me If the voltage across C631 should be there immediately After switch on or After a while?
DeleteIt is ramping up very quickly. Too quick to watch. My multimeter in MIN-MAX mode was too slow for it. So yes, it should be there immediately. Are you sure you have good spare parts, the DG302 in particular?
DeleteThey should. I sourced them from where you had suggested in your other post. Then having all gate voltage low After switch on is not normal, right?
DeleteI am now using fgds Everywhere....And seems that they switch correctly: when gate voltage rises they connect collector with emitter....
DeleteAs I said, I don't know what the expected measurements directly at the FETs are. I worked my way backwards from the SOS6 protection circuit to analyse its causes and all I know about it is written in the blog post.
DeleteHermann,
Deletethat's right, Your blog is to me the best in the web about this topic. So anyway I thank you for the time you spend here.
hi the C631 how microfarad and voltage is ?
ReplyDeletesorry my bad english
250V 4µ
Deletethank you
ReplyDeletehi my tv is tx-p46gt30b i don.t now the VS voltage
ReplyDeletemy Vs 215 V
is not subscribed on pdp panel
i changed 4 times the kit igbt after 10- 24 hour burned now. Possible is
fake igbt
now insert the FGD4536 + dissipators the temp is 60-65 grade celsius
Thanks Hermann!
ReplyDeleteHave repaired my TNPA5330 SN board and found this page very helpful!
Additionally to what you suggested, I had to replace diodes D16432 and D16433 (close to the power connector). Sparks below these diodes have burned the PCB. These diodes seem to be flyback diodes preventing high voltage spikes on VSUS.
Interestingly there were still sparks at the ribbon cable connector to the panel. The sparks happened where the output of IC14601 and IC14602 lie uninsulated next to each other at the panel connector SN21. So there must be spikes of high voltage difference between the outputs of these two chips.
There are more diodes which look like flyback diodes D14651… D14654. I replaced those as well and have also soldered an additional one to the back side of the board, located between the two ICs. Now I do not see any sparks any longer and the TV has worked for >10 hours without magic smoke.
Let’s see if it was lasting repair
Holger
Hi Holger,
Deletethanks for sharing. Your case has some new aspects. I wonder if the diodes you were using are up to the task. Why should the original configuration produce sparks?
Hi Hermann,
ReplyDeleteI must confess, I have not spent too much time in analyzing the schematic.
This is what I did (facts section):
1) 7 blinks => Just fixed the power board, put it back in and switched the TV on. => Bang! Power board killed again => Find the Alpengeist’s forum => Hope again to get it fixed
2) Got the repair kit for the SN board (and new transistors for the power board), replaced all parts and switched the TV on => Hurray, a picture!
3) Noticed a very bad smell after some time, so I had a closer look with opened back cover. There was an continuous(!) spark below D16432 and D16433, visible and audible. And often there was a visible spark at the top most ribbon cable and sometimes at one ribbon cable somewhere in the middle of the panel, usually shortly after switch on. (After some time these ribbon cable sparks stopped happening)
4) Removed D16432 and D16433 and they were badly burned, but somehow still working (The diode tester of my Multimeter was happy). The PCB was burned as well and I had to fill the hole with epoxy (UHU Sofortfest). The top ribbon cable had also a small burn mark. Tried to put on some epoxy glue to improve isolation.
5) Soldered in two standard 25ns fast switching diodes (Diotec ES1G DO-214AC 400 V 1 A). => No visible sparks at D16432 and D16433 any longer, but still sparks (not continuous) at the ribbon cable. => Better but not perfect yet, because these ribbon cables have narrow copper traces and I was worried that they will be destroyed over time.
6) Replaced D14652 and D14654 with the same 25ns fast switching diodes. Peeled of the epoxy glue from the ribbon cable (partly burned and it also did not stick very well). Used a very small drop of super glue this time.
7) Because there are other similar diodes all in parallel (and also a few mounting options for additional ones), I decided to add one to the backside of the board. (just scratched off the solder stop mask and soldered it in between IC14601 and IC14602)
8) => No sparks at the ribbon cable visible any longer. No strange smell. Looks good => Time for the “Children stress test”. TV has been running for many hours now without a problem or strange smell. I am optimistic the repair will last for a longer time.
My assumptions (not confirmed, measured or fully understood):
I see transformers, which seem to be used in switching power supplies for Vad and Vscn. I guess that D16432 and D16433 are flyback diodes which short the high voltage peak, after the current through these transformers is switched off. (self-induction).
Maybe these diodes were damaged over time (maybe not dimensioned big enough). These diodes are in parallel which indicates that one alone is not powerful/big enough. If the diodes don’t short these high voltage peaks, a spark may happen. But maybe it was just a bad solder connection at these diodes, which may have the same effect.
Regarding the diodes D14652 and D14654 I am not so sure about their function. But they look also like some protection diodes. (a few in parallel at various locations on the board) So I “blindly” replaced them. But It may just be the drop of super glue, which has fixed the isolation of the ribbon cable.
Cheers,
Holger
My TX-P42VT30 failed with the 7 blinks. I bought a repair kit on ebay, but the 6 transisors blew up again. Then I read that blog and realised the 30F131 and RJP30H2A were probably fake!
ReplyDeleteSo I will substitute as follows:
Q401/03 30F131 --> FGD4536
Q421/23 RJP30H2A --> FGD4536
Q441 DG302 (radiator) --> FGD4536
I am not planning to change the DAF30A (i replaced it, but does not seem to have burned yet!) neither IC502 Q531.
Do I run the risk to blew up again the FGD4536's?
I have ordered the FGD4536 on ebay (user monotor-09 who apparently is ok). I find it hard to find the right shop as it seems like a gambling game!
Thanks for your view.
Regards,
Your transistors were fake. I could not find any F131 nor RJP from China, which were not fake. If they don't come in an original Panasonic packaging, forget about them. Well, when the DAF dies it will kill all the transistors. But it is easy to substitute with the types I listed in my spare part post.
DeleteThank you.
ReplyDeleteIn the bad kit I also replaced Q661 by a RJP63G4, you never refer to that one in your blog, what should I substitute it with? FGD4536?
I have never seen an RJP63 before. The variety of IGBT FETs is astounding. I suggest the FGD will also replace this one.
DeleteThe RJP63 is rated 630V, 40A. Do we really reach 600V in a plasma TV?
Delete(The FGD is 360 volts)
Nah, 360 is sufficient.
DeleteThis is what I thought as well, 630V seems over the top!
DeleteThank you for a detailed description of the TV repair.
ReplyDeleteSorry for my english.
The problem with the seven blinkers was replaced by the replacement: on the board TNPA 5390 - Q300, Q301 (both short circuits), IC300 (maybe the worker can not check it), F102 (torn, not conductor). On the board TNPA 5330 was replaced without checking D421, D401, D461, Q421, Q422, Q423, Q401, Q402, Q403, Q451, Q441. Some of them were short-circuited, some were torn, some workers. Replaced without checking BD8693FVM and CPH5524. Everything is according to your description. TV is working! There were problems with connectors SN21 - SN28. While I switched them, I then turned on the TV then turned off. After 8-10 minutes of work (turned on,turned off, switched SN21 - SN28), my TV again got 7 blinks.
All of the above items are not short-circuited. Has not checked the breakthrough yet. But Q621, Q661 short-circuited, Q622, Q623 have been discontinued yet. I will replace them. Do I need to change D421, D401, D461, Q421, Q422, Q423, Q401, Q402, Q403, Q451, Q441 again? Maybe I need to replace some other elements? I would be very grateful for any of your information. Best regards, Andrew.
Only shorted devices need to be replaced first. If the tv is not running after that I suggest you try my fault finding strategy.
DeleteI can't say what else could be broken.
Made some explosive progress.
ReplyDeleteI changed D421/Q401/402/403/421/422/423/Q441, then I still had 6 blinks.
Then I changed Q451/IC502/Q531, it works few secs, then big explosion
of all Q401/402/403/421/422/423!!!!
The fuse on the power supply did not blow up that time.
I am sure of D421 (bought it from Farnell STTH30R04G)
The FGD4536 were bought from monitor-09 (ebay) user. I tested them with your schema opening around 4.23V and fully open around 5.2V.
Not sure what to do anymore, where to buy these FGD4536 if the one I bought were fake?
Help please?
Provided that none of the buffers have a short, with good parts there is no reason for the scan board to blow up. You can find sources for parts in my post https://alpengeist-tvrepair.blogspot.com/2017/03/replacement-of-discontinued-panasonic.html
DeleteAs my fellow 'fixer' Eric seems to have found, if you don't notice an open circuit 7.5ohm resistor in one or more of the 'usual 6' IGBT gates, the remainder will likely be overloaded, leading to more casualties in the new parts.
ReplyDeleteI replaced Q401/402403/42/422/423 with FGD's started TV, I got 6 blinks, good move!
ReplyDeleteI then replaced R507/IC16502/Q531, the TV worked during one hour.
After one hour 6 blinks again, I noticed that Q441 was short circuit. I replaced it with a DG102 (found on a old SS card), start again. It worked for 5mn, then Q441 short again. I thought this may be a bad DG302 on the SS card, so changed it again (from another SS card).
Worked during few minutes, then Q441 short again, back to 6 blinks.
Any idea what could be wrong? Does the change of Q441 always requires change of the Q531 and IC502?
Views will be appreciated, thanks.
Have you checked the green resistor next to the DG302? IC502 might also be broken. Haven't seen that before, but your case looks different.
DeleteOk, I will change ic and driver then.
ReplyDeleteI read that I can use FGD instead of DG302 for Q441 and Q451, is it correct?
I am asking because I compared the result of the test of FGD versus DG302 with your IGBT testing schema and I find really different voltages for opening (3 versus 5 volts), thus my question.
Thanks again, really appreciated.
The FGD fit everywhere, provided they are genuine. My 55VT30 is running with them no problem. I never understood why Panasonic chose such a variety of IGBT transistors. Maybe in detail some are better suited for specific tasks. Kinda perfectionism, I guess.
DeleteI changed Q451/Q551 the 2 drivers, the 2 IC's.
DeleteIt worked during 4 hours, then back to 6 blinks.
Nothing short cut now.
Voltage at C631 starts at 80 volts, then after few secs goes up to 190V then TV stops.
I wonder what else could it be? Why does it work during 4 hours?
After checking all resistors/igbt/diode, still 6 blinks. I am really stuck, help please !!!
ReplyDeleteRegards,
I honestly don't know how to help :-/ My suspicion is that you have some bad parts. Im mean, either they work or they don't. If they die after 4h they are not ok.
DeleteOk, let say it is a bad part. I got the IC from ali URL (the one on your site) and the drivers from farnell. I have changed the ones on high voltage recovery with some found on a SS card, shall I change the low recovery as well?
DeleteIn other words does 6 blinks means only recovery voltage issue or could mean something else? (e.g. bad power supply, fan issue ....)
Thanks again.
If the voltage at C631 overshoots, you have a problem in the recovery H section.
DeleteTaking the IC's from an old TNPA5331 instead of using the ones I bought on aliexpress (in the link provided on this site, not offensive, only a Warning about these sites who are over time not quality consistent) has fixed my issue. TV is working again.
DeleteThanks again for your support.
Thanks for reporting! Which one exactly? I'm going to modify my list.
DeleteYeah, those dealers get their stuff from anywhere they can. No guarantees.
Servus Hermann,
ReplyDeleteI successfully refurbished a TX-P50GT30 with the 7 blink error (the screw disaster). Picture starts but there are now two thick black horizontal lines in the lower half of the display. I suppose, that the ribbons to the lower buffer (SD-board) are not exactly, well plugged in, isn't it? Has anybody a similar problem or hint? It seems not to be easy, to re-connect the ribbons to the buffers... :-(
Or can this be another problem?
Kind Regards, Martin
It's similar to here: https://www.badcaps.net/forum/showthread.php?t=40943
DeleteI use 2 pens (in wood), I place them vertically behind the ribbon, to prevent the ribbon to move back when closing the brown lid. I do not press on the flat part of the ribbon, the pens are perpendicular to it.
DeleteFor the 50 inch, it won't be necessary to unplug the ribbons as the buffer boards can be separated from the scan board. Only the 42 inch has a combined scan & buffer board.
DeleteI used angled pliers with tape wrapped around the tips to be able to thoroughly push the ribbons in. You need to make sure that the little notches on the sides are all the way in and not bent.
Hello Hermann,
DeleteI had to replace a faulty SU-board, too, because there were several shorts across two connectors to the panel-ribbons...
I'll give another approach. Thanks for all advices!
Regards, Martin
Success! But it was a sisyphean task to get the ribbons absolutely correct into the connectors... The plasma has risen like a phoenix from the ashes and works fine again. Thanks to all for any hints!
DeleteKind Regards, Martin
Hello Hermann,
ReplyDeleteI want to thank you for sharing your repair experience which has helped me fixed my ST30. Excellent post!
*** TV Fixed Per Your Blog ***
When my ST30 broke it had the exact symptom as you described (initially 7 blinks, then became 6 blinks after replacing the 6 MOSFETs Q401, 402 403, 421, 422 423 and a driver IC502, as well as the power board Q300, Q301 and the 4A fuse). The 6 blinks was then fixed after replacing Q451. I could not have fixed it without your blog as none of the repair sites/youtube videos that I visited mentioned anything about the Q451 issue.
*** POP Sound During Power Up ***
My ST30 is now working nearly perfectly and no issues at all with regard to picture and sound. However, something really puzzles me. When the TV is turned on when it is cold there is a pop sound which resembles something knocking on the back cover. The TV works perfectly other than that. By turning on cold I mean after being off for more than 10 minutes or so by remote controller, or just plug in power socket when it has been unplugged for 10 minutes or so.
*** POP Sound Not Mechanical or Audio ***
I am really puzzled as I am absolutely sure it was not mechanical knocking. I was not the speakers either as after I disconnected the speaker wire the problem was still there.
I then suspected the capacitors on the power board (82uF 450V, 33uF 450V, 190uF 250V, 820uF 80V, 1500uF 63V). I am now thinking if some of these capacitors are not as good as they should be and the popping was caused by suboptimal charging of these capacitors.
Have you experienced anything like this before? Thanks.
Hi Eric,
Deletehappy to hear that my story was helping you. About the pop sound: I never experienced anything like this. It is difficult to asses in words, though. If I heard that "pop" I might have ideas about it. I doubt that electrolytic caps can make that sound. If they did, they would be seriously damaged. I know that some high voltage foil caps can do that when an impulse hits them, or even the transformers. It cannot hurt to check the power supply for bad solder joints.
When I am not able to locate a sound, I switch of the light in a dark room and focus purely on listening. It is amazing how the eyes can distort the ear's perception.
Hi Hermann,
ReplyDeleteThanks for your advice about bad solder joints. I did try to hold the transformers on power board and tried to move it and they felt secure. However, that did not rule out the possibility of bad solders joint in one of the legs, though. I have ordered new capacitors and plan to replace them any as my 42ST30 have been 7 years old. Will then inspect the solder joints careful. Cheers.
Will try the listening in the dark, too.
ReplyDeleteHi Hermann,
ReplyDeleteAs a update, I have fixed the pop sound problem. These were what I did in the process:
1. Replaced all the large capacitors, but that did not help. (BTW, despite having been used for 7 years I found that the original capacitors were of quite good condition with regard to capacitance, ESR and VLoss values after I measured them after taking out of the circuit board. The values are similar to the new ones)
2. I then inspected for bad solder joints on the power board especially the large components like transformers, MOSFETS, etc but did not find any bad joints.
3. I then checked the other components like diodes, resistors.
4. At last, I found a faulty large ceramic thermal fuse resistor which measured open. It was a 5W 15-Ohm thermal fuse resistor which was connected to one of the two relays. I confirmed it was faulty by comparing it with an identical resistor next to it.
5. I replaced the faulty 5W thermal fuse resistor and the pop sound went away!
Now my TV works perfectly and I am very happy with it.
Thank you again for your sharing your repair experience. It has been a great help.
Interesting! So one of those resistors didn't take the SN board short too well, I suppose.
DeleteI think it is safe to say that those Pana Plasmas never have any capacitor issues.
Герман напишите пожалуйста
DeleteYes, indeed. The Pana Plasmas use high quality capacitors. It would have save me quite a bit of work if I had checked the resistors first. What led me to suspect the capacitors was that the loundness of the pop sound seemed to be related to the charging state of 82uF 450V and 33uF 450V capacitors, the lower the voltage the louder the pop sound.
ReplyDeleteBTW, before the resistor fix the pop sound was still there even if I discounted the power connector to the SN board and the other board (SC board?). As long as the relays click the pop sound was there.
ReplyDeleteI still have not come up with a good theory to explain the pop sound. The theory I have in mind now is the possibility of an internal spark within the 5W resistor after the thermal fuse blew and left a electrical gap within. When the relay kicks in there is a spark across the electrical gap and caused the pop sound which was amplified by power board and the back cover as vibration membranes.
Wow...awesome post. My Tv has a PANASONIC TNPA5335 or (sub part TXNSC1NVUUB) SC board. Even though the TVs are slightly different I found this post to be very informative.
ReplyDeletemy tv Made a loud pop, slight electrical burn smell, and then a 6 blink code. After checking it out I found a transistor/IGBT? and diode that are blown. Checked all other Q's and D's and they seem good. I found a parts repair kit from a few places but I'm not sure if the transistor I need. I've emailed a couple of the repair it sellers ShopJimmy was one and haven't really got a definite answer.
The labeling on the transistor reads R2507A with a Q underneath. It's been a little difficult trying to find this exact part. I'm also wondering if the board can be fixed as it's fairly charred and crusty around the circuits in that area. I've repair one circuit in my life and I think I can do this one. If I can't , we're going to scrap the TV and buy a new one. Thought about buying a repaired board. But at $100+ It's not worth it comparing the low price these days. Any info you may have would be well appreciated. I have good photos of that area, but not sure if I can upload them here.
The 5535 is the one for the 46 inch and bigger. I know those boards well, however I had only 7 blinks.
DeleteYou need to read the label of the part that is printed on the board. It should read someting like Qxxx or Dxxx, respectively. R2507A does not ring a bell. Never seen that before.
Hi. I have P50S30, did a kit repair to TNPA5331 board that lasted a week, then I did the same kit repair and this time fixed the ground screw problem that caused it. Lasted a year of occasional, but more recent use. Just went "pop" with burning smell at power on. Now, no screen,6 blink. Took off cover, now I see burnt spot on pcb of TPNA5331 in location IC784 with a leg burnt off on component MIP391. The burnt leg is called BR described as brown-out leg connected to ground. Now I just noticed, all the board screws with spring load washers are looser than when I put them on over a little solder....(a year ago) The burnt area is spread over a patch where 50 small tiny points of metal appear in the pcb, between the MIP3391 and the nearby 250v-140uf capacitor. It looks like power was looking for ground and took this path. My question is, I can buy another MIP391 to put in this board, have you heard of this before? Or should I throw out the panny like everyone else has? Before I let you go, I checked continuity on the transistors that have been replaced and get a beep on the outside legs from half of them. The middle leg goes to ground. These all dissipate heat through a puddle of solder underneath, there is no heat sinks. An older Pioneer I have is full of heat sinks everywhere and gives me no problems. In one of your blogs, you say panny went back to heat sinks at some point, and better ground points, gee I wonder why. Thanks -Greg
ReplyDeleteI used your IGBT test circuit to verify some suspected Chinese fake DG402RPs that I bought on eBay after failing to repair a TNPA5105 from a 50" Panasonic plasma.
ReplyDeleteI increased the supply voltage and lowered the load resistance with the test devices fitted to a heat sink. They failed short once the collector current was pushed past 3 amps. I tried a known good Panasonic 2PG011 in the same circuit and it happily handled 10 amps, no problem.
It's nice to know my fault finding is ok but doesn't solve the supply problem of reliable replacement parts now plasma as a technology is history.
Andy
Hi, I'm trying to fix a TNPA5457 (YSUS board) of a TX-P42GW30.
ReplyDeleteI already replaced D401 & 421 with the same type, the Q401, 402, 403, 421, 422, 423, 531, 621, 622, 623, 661 were exchanged with RJP63K2 and the Q600 was replaced by a MDD14N25. (All came as part of a repair kit.)
Now the circuit board still has a short at SN2 (the power supply plug).
Should I replace the RJP30K3 too (not included in the repair kit) or did I maybe order the wrong repair kit for this fault?
Best regards, Daniel
I haven't fixed any plasmas for a while now. Interesting to see new replacement parts popping up.
DeleteWell, I cannot tell you which part has the short. You need to measure it. When I repaired the boards I removed the shorted parts until there was no measurable short anymore. That gave me confidence that I did not miss anything. You do know that the 42 inch blows up its power supply as well?
Thank you a load for this awesome and detailed troubleshooting, it just helped me repairing said TV after almost giving up on it!
ReplyDeleteIt was a hassle getting those panel flex connectors back in their place, at first glance I feared that I'd have damaged the driver chips. What a relief that it was just the connector.
Thanks a lot and greetings from germany, keep up the good work!
Hi, I have a problem on a TX-P42VT30E TV.
ReplyDeleteEvery now and then it switches off and on again without giving errors. It can be the switch.
Thank you
Hello...I measured C631 The recovery voltage 220V in first plug than suddenly...green light came in than in one sec. It's gone with so little bzzzzz sound...than C631 Voltage drop 220V to 5v.(a linear drop.. first 190v,152,132.....5V etc.) I change all recovery H, companions... Can you give any advice to me pls?
ReplyDeleteGreat blog. Thanks. I have a Panasonic VIERA TC-P55GT30
ReplyDeleteAs far as I know the part that is damaged is TNPA5335BA SC Board
One of the transistors/diodes? has blown. The labeling on the part is R2057A. And a smaller one near it has blown also. I have good photos of the damage.
Not sure how to put a photo in the reply here, but I have good photos of it. Can't seem to find that exact part. Plenty of repair parts for this though, so I may just buy a kit and see plug it on there. If you have any idea of how to find the right part with that number please let me know.
Hi,
Deleteyou are lucky. The 50 and 55 models are much easier to repair. The faults are always the same. Look here: https://alpengeist-tvrepair.blogspot.com/2015/05/panasonic-tx-p50gt30e-once-more-7-blink.html
If you cannot source the parts yourself, which is pretty difficult, I suggest you check one of the following trustworthy sites for repair kits:
https://spares2repair.co.uk/
http://www.lcdparts.net/LCDC2.aspx
http://www.ebay.co.uk/usr/gtvwatford
http://www.lcd-plasma-parts.co.uk/
http://www.plasma-lcd-led-onderdelen.nl/
http://www.ohmsupplies.co.uk/
Hi Alpengeist, got mine txp42st30a from 7 blinks to 6 and I can't get the service manual from the site you recommeded.It says not found. Any idea? Many thanks in advance.
ReplyDeleteGot it at last after several attempts.Thank you for sharing your tremendous knowledge in this blog .The reason I need this schematic diagram is to understand the circuitry which connects Q531,I have noticed the circuit where it sits and was measured short between several points. Found it out after replacing the open circuited Q441. A new Q531 does not show any shortage.
ReplyDeleteFurther investigation shown IC502 pin 7 shorted to the ground, giving a false impression that Q531 was to blame.Awaiting a new IC502 and hopefully it will bring the TV back to life.The initial big bang inside the TV causes damages so far to components Q401 Q402 Q403 Q421 Q422 Q423 Q441 and IC502 in SN1 board plus Q300 Q301 F102 in the Power board.
ReplyDeleteYes, this looks like the classic damage. Q451 might be in for a change, too. The 42inch cause quite a lot of work. The ribbon cables are the final test of your patience. The older the devices are, the more difficult this gets due to wear of the contacts.
DeleteYes I will order a replacement Q451 just in case. Thank you so much again for sharing so much valuable information and knowledge about fixing this particular model.Will report back the outcome later on.
ReplyDeleteHi Alpengeist, I am back and ready to report my latest progress. After changing the shorted IC 502 plus Q451 as recommend, the TV stayed on for about a minute and then came with a big bang, found D421 blown open. Further check indicated short circuit with Q421 Q422 Q423 D401 Q402 Q403 plus Q300 Q301 as well as a blown fuse F102. All the above faulty components were replaced with the repair kits from eBay. Not sure yet that Q441 Q531 IC502 Q451 Q551 IC522 all gone with them or not. Need a bit of time for reflection.
ReplyDeleteOh dear, it looks as if the repair kit for the scan board was garbage. I think you can only trust kits in the original Panasonic packaging these days. All the other ones are most likely random junk from China.
DeleteMissed to mention Q401, sorry.
ReplyDeleteWhere can I source the genuine original parts? if I may ask Alpengeist.
ReplyDeleteI don't know. I collected working parts three years ago. My chinese sources from back then are no good anymore, that's for sure.
DeleteThanks for that anyway and I shall find a way around this problem. My best regards to you and your family.
ReplyDeleteThank you and good luck!
DeleteHello Hermann,
ReplyDeletefirst of all, congratulazioni for your forum.
My panasonic 42" with TNPA5390 and TPA5330, was resume from 7 blink led after replacing these components:
TNPA5330
Q421,Q422,Q423,Q401,Q402,Q403
D401
POWER SUPPLY TNPA5390
Q300,Q301,F102
After these change I got 6 LED blinking. After remplace the
Q531,D421,IC502
The TV was ON for a few hours now again 7 blinking LED.
No previous components are in fault.
I noticed that on SN2 connector I do not have Hight voltage and Q300, Q301, F102 are OK. I have checked also the 5V (C561) and 15V (on TP82) near the connector SN20 and I read both.
What you suggest ? Thanks and regards
Any suggestioni? Please
DeleteI don't know. I had one similar case a couple of months ago and could not find the cause, either. None of the replaces parts were faulty. I gave up on that one.
DeleteAny suggestions? Please
ReplyDeleteI have at last got round and obtain the original diodes and transistors to replace the fake faulty one and the set was working again for hours with no major problem apart from one or two fade horizontal bars at the bottom of the screen and I remembered you did mention such problem was caused by the ribbon cable connector.The next day I tried to reconnect with all the ribbon cables and resulting much worse than before, so I tried to reconnect it one by one to see which one was causing the problems ,this time the set was on while I was doing it and the set was switched off when I went to the fourth connector.And the 6/7 brinks reappeared again.This time when I checked the board again and I did find C842 gone short. It was very likely the fiddling with the cable while the set was on did cause shortage to the buffer IC, very foolish of me.It might be the last straw for me now. What do you think, Alpengeist?
ReplyDeleteYou plugged the cables live? Ohhhh dear, that was a mistake. We are talking high voltages here and the buffer hate to get shorted. C842 shorted?? I'd rather think that something in the periphery is short, not the cap itself. Well, to test the buffers, switch the multimeter to continuity and walk down the pins of the flat cable socket against ground. A defect buffer will reveal itself with a different "beep-pattern".
DeleteAnd how could I determine which particular IC has gone short ? Thanks in advance.
ReplyDeleteMe,as a hard headed guy, tried to get to the bottom of it and discovered that buffer IC804 had several pins shorted to the ground as a few connection points of the connector SN27 showing up shorted over the meter. Could this be the culprit?
ReplyDeleteIt sure is! This board is toast now, I'm afraid :-/
DeleteIncidentally, I did buy 2 working tnpa5331 boards and taken out all the necessary diodes and transistors to be reused. By doing that it is almost 100% guarantee them as original genuine parts.And it costed me under 18 pounds sterling for two boards. It fired up without any problems until the latest episode.
ReplyDeleteI understand it is very difficult to get the buffer IC out of the PCB and with your vast experience can you offer me a good way of doing that.
ReplyDeleteThis is where it ends, my friend ;-)
DeleteI will attempt to get it removed when I feel a bit more confident about it and it cannot cause more damage than it did to the board I must say. Thanks again for your time.
ReplyDeleteThe buffer ICs can be replaced. You need good soldering skills though. I replaced two on one of these. Carefully scrape as much of the grey silicone away. A fingernail or plastic scraper is best. I then very gently cut the legs of the failed chip down all four sides using a scalpel. The legs can then be removed using tweezers and a soldering iron. I then used a heat gun to remove the chip as it will still be stuck to the board. Clean up all the PCB pads with wick and liquid flux and then fit your new chip.
ReplyDeleteWhich component should be replaced when the 200v is missing on the SN 2 connector? Thanks
ReplyDeleteHi Hermann, Today, to have no doubts, I replaced all the components shipped with the PANASONIC label, including Q451 (DG302) the problem persists 7 flashing red LEDs. However, I noticed that in the TNPA5390 power supply part, the Zener diode D224 near the word LIVE CIRCUIT is open, is it correct that it must be like this? thanks a lot.
DeleteHave you used the diode test mode on the multimeter? Diodes can appear are open in ohm test mode. Zeners can also be open in reverse direction if the Zener voltage is higher than the multimeter's test voltage.
DeleteHave you checked whether the power supply starts up? This can be tested in min-max mode of the multimeter. When the set goes into protection the power supply is shut down. Thus, when it blinks, you won't see anything.
Yes of course, diode mode and mark open in both directions.
DeleteI will check the power start-up.
Well, then this diode is broken. No need to test anything else before it isn't replaced.
DeleteWhat code/type for D224 to buy it? Thanks a lot for your time. Regards
DeleteCan't say. The service manual does not reveal the type.
DeleteJust in case somebody else is interested in: D224 B0BA01500003 is said in other forums to be a 15V, 0.5A Zenerdiode. Diode D221, 222, 225 closeby are the same type.
DeleteThanks for instruction. I was able to fix my 42ST30. After fixing 7blinks (Q421,Q422,Q423,Q401,Q402,Q403,Q501,IC501,Q502,IC502,D401 and D421) I get 6blinks.
ReplyDeleteVoltage on C631 was to high. At the end it was Q451 - from Recovery L. Q441 from rec H was fine.