troubleshooting bn44-00598a

[soul1988]

I'm troubleshooting a bn44-00598a from samsung pn43f4500.
Removed the power supply and tested the voltages, had no voltage in VA and VS, a few minutes with the multimeter and encounter 4 IGBT in short circuit (2 RJP30H1DPD, 2 FGD4536).
I replaced them, tested by sorting PS_on to gnd and VS and VA were good.
Before putting the power supply in place tested again with the mainboard, when I plugged in the mains the two IGBT(FGD4536) from VA blew up immediately.
I've lost a few hours trying to find the cause for this but without any success.

I would like to know if someone here in the forum with more experience in smps from Plasma tv's knows what might be causing this.

[R_J]

Re: troubleshooting bn44-00598a

Usually when fets go shorted they damage the parts in the gate circuit or the gate drive ic, there is a repair kit available

[Unspun01]

Re: troubleshooting bn44-00598a

Sounds like you repaired the power supply, but did not check the X-Main or Y-main "sustain" boards.

I suggest you re-repair the power supply board BN44-00598A as you did before to get back the VS and VA voltages.

Connecting to mainboard should be ok, but DO NOT CONNECT TO X-MAIN or Y-MAIN BOARDS YET.

Test X-Main and Y-main boards for shorted IGBTS.

[soul1988]

Re: troubleshooting bn44-00598a

To clarify I still have VS and VA voltage, what I do not have is VA out to the screen.
I did not connect any other board besides the main one.

Looking at the connections it seems that U4010 is the gate driver, but unfortunately it has no part number. Unless someone knows the part number I'm screwed.

[Unspun01]

Re: troubleshooting bn44-00598a

Please be more specific because what you are telling us makes no sense.

If you have VA and VS on power supply, then your power supply is working. Is this true? Yes/No?

If you have no "VA out to the screen" as you put it, where are you making this measurement? Power supply has no connection to panel - only X-Main and Y-Main. This does not look like a power supply problem.

I asked you to check the X-Main and Y-Main boards (for shorts) which accept VA and VS from power supply. Without any connection to power supply, check the X and Y Main boards. They may have damaged your power supply.

Please reply with more clear descriptions of what you are doing.

[soul1988]

Re: troubleshooting bn44-00598a

Sorry for my limited description, English is not my native language.
I'm not sure but I think this smps has the integrated x-main.
I still have not connected to y-main because the smps is not fully working, but replaced some components that were burned.
The board has a VA voltage at the test point but there is no output for the flat ribbon cable of the screen.

The two FGD4536 are responsible for the VA output to screen but I can not replace them until I find the cause of them burning.

I leave some pictures and a video to see if it helps.

https://youtu.be/St38_xiSioM
https://youtu.be/O74AkpF7R6k

[R_J]

Re: troubleshooting bn44-00598a

The Va voltage goes to the plug CN4006. There are likely shorted fets for the Z-sus part of the board (on the back of the board)
What are the locations of the fets that keep shorting?

[R_J]

Re: troubleshooting bn44-00598a

If you have Vs voltage and you have Va voltage, that part of the power supply is ok

You may have a fault with the SVT_XOUT voltage circuit
The SVT_XOUT voltage comes from the Vs voltage and is controled by a couple fets Q4004 & Q4005 and also Q4003 & Q4002

[soul1988]

Re: troubleshooting bn44-00598a

Did not know that this part of the circuit is called SVT_XOUT thought it was part of the VA circuit, I apologize for the confusion it is the first time I repair a Power supply from a plasma tv.

Yes the initial fault I found was the four fets, Q4004 Q4005(RJP30H1DPD) and Q4002 Q4003(FGD4536).

Q4002 Q4003 blew up when I tested the power supply with the mainboard attached, and that's the fault I'm trying to find.

[R_J]

Re: troubleshooting bn44-00598a

The proble could be with the drive to the fets, check the gate resistors (if they have them) and it could be that the gate drive ic's are bad. When the fet shorts, it can supply high voltage back to the gate circuit and damage the ic.
If you look at post #2 you will see they include those two 8 pin ic's with the kit. If you did not replace them, you should

[soul1988]

Re: troubleshooting bn44-00598a

In my second post, the image is of what I believe to be the driver ic, Looking at the connections it goes to the gate of Q4002 and Q4003.
In this part of the circuit is the only 8-pin IC there is no other 8-pin, none of the pins appear to be shorted not wanting to say that it is in good working order.

Being the cause of malfunction without the part number I can not replace them.

[R_J]

Re: troubleshooting bn44-00598a

Use something like alcohol to clean the top of the ic, you might see the number, if not I will try and find it

When the fets short are all three pins shorted together?
The ic Might be a BD8693 Some others have used FAN73711 as replacement (I don't know if it worked correctly)

[Unspun01]

Re: troubleshooting bn44-00598a

Here's some high resolution photos of bn44-00598a power supply.

R4064 and R4022 seem to be gate connected resistors for Q4002.
R4082 and R4021 seem to be gate connected resistors for Q4003.

Both are driven by U4010.

You could check for shorts to ground for U4010. Or with Q4002 and Q4003 removed, you could check for VCC at U4010. My guess is that IC is damaged even if not shorted and may be taking the transistors with it.

Also with the MOSFETs removed, re-check the circuit board for shorts to make sure none still exist (there are diodes in the mosfet circuit also). And as R_J stated, check the values of the gate resistors.

[soul1988]

Re: troubleshooting bn44-00598a

All resistors on the gate driver side has the resistance value equal to its codes.

Looking to the pinout from the circuit diagram match the connection of U4010 on the supply. I already ordered the BD8693, now it's a matter of waiting for him to arrive and test.
As soon as I have the part, I'll tell if it's all up and running.

I would like to thank all those who helped me troubleshooting this board.

[R_J]

Re: troubleshooting bn44-00598a

You can can test the fets inside the ic to see if they are shorted, If one is shorted then you know you found the problem.

[malik4]

Re: troubleshooting bn44-00597a

help: ineed schematic diagram

bn44-00597a

[spawn784]

Re: troubleshooting bn44-00598a

Could You repair power supply?