Samsung PS43f4500AWXXU Plasma Faulty Y Board

[reessi]

The tv turned off with a bang. I have found 2 parts blown short on the Y Board:

Q5019 (FGD4536 - 360V, 50A, PDP IGBT)
D5030 (SF10A400HD - ULTRA FAST RECOVERY POWER RECTIFIER)

I have spent a long time trying to find other shorts as when I replace them they blow again.

I bought 5 of each from china so have some spare still.

I see other people replaced these and the tv worked. I see mention of the gate driver having failed but there are no shorts on it or between the pins on it but I guess it could be faulty.

I could not find a schematic only a service manual which has no schematics...

U5016 looks to be the gate driver (written on it 8683GVR).
There is no result for it in google!!

I am not familiar at all with plasma tvs...

[Biruslapio]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

There are a lot of fake FGDs, did you physically compare them to the original one that was on the board?
Shorts could be on the output pin of the buffer chips (R2A20292BFT), no problem with the heatsink mounted IGBTs? No open resistors?

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

Actually both the parts I bought look slightly different. Different print and on the FGD it has a dimple in the middle on the original! See my photo, but it is hard to take a picture. Can they be produced in different factorys or definitly fakes? I checked them for shorts. There is a good FGD on the board, I will remove and compare readings...

I have already tested the buffer chips by running my probe across the output connecters testing for shorts to ground and found none. I have also tested all the resistors around the FGD, there are some 15 ohms and 10k ones. All tested fine. I had checked them as another video a guy found one of the 15 ohms open.

So I went back and checked the IGBT's on the heatsink and found one of them shorted -> Q5029 (Part no. 30J127). The reason I didn't spot this before is I was testing all the pins to ground! This time I tested the pins between themselves. It does not have a direct connection to ground. But it is connected directly to D5030.

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

I have ordered some 30J127 parts. So will report back when they arrive..

[ReeceyBurger123]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

Nice one.

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

Hello, I am back with this TV. So after replacing the parts from china, they popped again!!

I compared diode readings of the 30J127 china ones and some of the original ones that hadn't died on the board and they were very different so I am presuming they are fake..

I didn't want to keep ordering parts not knowing if they were real or not. I would just be chasing my tail all day. Maybe the other parts I replaced are also fake!!

So I ordered a board from Aliexpress for £20. It works but there were horizontal lines (see pic). So I removed some of the flexes to the screen to see which ones were responsible. Second and third from the the top are. Then I looked under the microscope and could see some of the pins on the third one were not coming down much when you press the locking the tab. So I bent them slightly under the microscope. I did not touch the other connector yet.

When I powered it on the whole picture has distortion! (see pic) but it does appear through the distortion that I fixed all but one line on that section.

I checked the service manual which shows picture defects and solutions but this distortion is not shown.

Any ideas what is causing this?

I also removed some of the silicon on the chip connected to that tab but not all and under the microscope there is no damage. I was just checking for dry solder joints. Removing this flex blanks that whole section but does not affect the new distortion I have!

Another option is I move all the needed parts to the old board but I am afraid to do that and it pop again!

Many thanks.

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

The first pic of purple screen is perfect apart from the lines, it is just the camera not picking up well!

[dick_barton]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

You may well need to carefully reseat the Ybuffer ribbons that are in line with the lines on the screen.

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

Yeah I've tried that many times and now I have all the extra distortion! Cheers

[Biruslapio]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

The distortion/pixelation is a sustain problem, probably the panel cables are shorting out since it only happens when you reseat them in a specific position.

It is a bad idea to bend panel cables and remove glue on the buffer ICs, you can test them with a multimeter where the panel connects. The connectors slide in naturally, bending does not help, cleaning the Y-SUS output pins could.

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

Hi mate, I did not bend the panel cables in any way. I bent the pins down in the connectors on the board which has fixed some of the horizontal lines but now I still have all the pixelation still. I have checked for shorts on the I.C. between pins next to each other and to GND & found none. I also checked for shorts the same way on the connectors.

Any ideas what else I can check. Dis-connecting the cables to the connector and IC I messed around with blanks that part of the screen but the other sections are still pixelated!

Cheers.

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

Also why is there glue on the buffer chips? If that buffer chip has failed will is affect all the other buffer chips even if I have dis-connected the cables? When I dis-connected the cables before the pixelation problem it just blanked that section, are they not independant to each other?

I could move a buffer chip from the old board to this board if it has failed..

[Biruslapio]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

Glue on buffer chips are to protect the pins that are so close to each other from dust and humidity, they output a 500V pk/pk signal.

You won't find shorts to common GND on the ICs, they use the floating ground as GND, they should measure as a diode, around 0.6~1V forward voltage from FGND to the panel output pins, and if they're bad it would be open or shorted, the ICs are tied to each trace that goes to the display, if one is bad it can affect the whole picture, but won't cause horizontal lines in other ICs circuit.

I did not mean the panel cables, but the pins as you stated, try to leave them as they were.

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

Ok but the pins I bent now those horixontal lines are fixed apart from one. What do you think I should do now? Can that chip I removed the glue to affect the screen even with the cables dis-connected that it feeds?

Cheers

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

If that IC is faulty and I remove it for testing should the screen then work?

[Biruslapio]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

Just removing the glue won't affect the IC, it's there for long term preservation against oxidation.

Removing the panel cable is enough to isolate any defective IC that has it's output pins shorted, but if the input is also damaged, it won't help. It will create a horizontal band on the panel that will be unpowered and completely unlit, don't mess with these cables with the TV on of course.

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

Yeah I always turn off first, I have tried removing different cables to the panel and it does just that leave a black band but I do not know what to do about the pixelation problem that has appeared now!

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

I have tried running each cable on it's own so one lit band at a time but always they are pixelated!

[Biruslapio]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

The Y-SUS is damaged then, does not look like an X-main problem (in this TV X-main is part of the power supply board).

[reessi]

Re: Samsung PS43f4500AWXXU Plasma Faulty Y Board

Any idea what I can check for to fix it? I still have the old board so maybe I can use some parts off that?