Samsung BN44-00261B power/inverter board

[KJINTF]

I have a Samsung LN32B650 LCD TV with the above power board. Came in with no picture sound OK. Picked up a schematic of the board and found the secondary fuse which supplies power to the inverter MOSFETS open, additionally both FDPF5N50UT inverter FETS shorted. The transformers look fine with no signs of heat issues plus all the small caps across the HV look OK.

My questions
Have any of you seen this problem before?
Is there a reason why the FETS would die?
Should I be looking for more defective components downstream of the FETS?

Thanks for the help - as always it's greatly appreciated

[tom66]

Re: Samsung BN44-00261B power/inverter board

The FETs have likely died from overheating and/or being undersized.

If there is a transformer coupling the gate drive, then the other components driving the FETs should be fine, only the FETs and fuse need replacement.

Check nearby diodes, too...

[KJINTF]

Re: Samsung BN44-00261B power/inverter board

Thanks
I did check the diodes - all good
Noticed not much heat sink compound was used on the FETS.
Ordered 10 of the FETS and will hope for the best

[KJINTF]

Re: Samsung BN44-00261B power/inverter board

Thought you might like the schematic
The FETS in question are on page 2 top center position IDs Q1803 and Q1804

[tom66]

Re: Samsung BN44-00261B power/inverter board

It looks like the worst that can happen is the FETs get damaged. The gate drive is isolated and limited to each gate-source junction.

[Jaco.J.v.V]

Hello there, have a problem too with this boar, i was given this tv and when i opend it i found a few peoblems... Firstly the cap was sticked to the bk of the tv, 1 resistor is blown and its difficult to make out the band colour, lastly there is a part missing at Icm801, not this board is REV 2.0 and i cant find a diagram for it. All i find is rev1 and 1.2. I need to kniw what the missing part number is to get a new part

[nomoresonys]

Post a good clear picture of this board.