Samsung LN40B500P3F No Power Doesn’t Turn On

Opening up the back of this TV, it is a relatively newer design with a combined power supply/inverter board.  There were no big capacitors which are the usual suspects with this failure.  This TV uses model BN44-00264A power supply.  There are a few posts on about this problem with the likely suspect failed FET transistors.  With the back opened, I tested the two fuses on the combined power supply/inverter board and FM802S was blown.  If you replace the fuse, it will just blow again.  I removed QI820 and QI821 and they tested as shorts on my ESR meter.  The FETs are a little tricky to remove since they need to be unscrewed from the heatsink and the drain and source pins have small grommets in the holes.  I ordered replacements on Digikey: FETs are part# FDPF7N50U_G-ND and the fuse is F2376-ND.

After replacing the two FETs and fuse, the TV powered up with no issue.

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