Philips 43PFS5803

[Sraros]

Hello,
I received this 43' TV. It has no standby voltage and the owner had it on when it banged and shut off.
With a quick look I found one resistor burnt on top side
R9101 0.24Ω
and at the back smd resistor R9142 22Ω
Both were reading with MM in MΩ
The schematic is attached to this post.
I investigated nearby components and found N-Mosfet Q9101 is K8A65D1 instead of STF24NM65N as per schematic. The resistance between drain and source is 4.4Ω. Should I consider it shorted and the culprit of the failure or is this normal?

The photos uploaded are after resoldering new resistors

[Sraros]

Re: Philips 43PFS5803

Correction R9104 not R9142.
Also R9106 and R9103 are also burnt reading over 10kΩ
IC U9101 seems ok

[dskall]

Re: Philips 43PFS5803

Had the mosfet been changed before? I think one was 8A and called for 24A.

[R_J]

Re: Philips 43PFS5803

If Q9101 shorted and R9101 is open, U9101 is damaged as it would have seen about +300vdc on pin 4(CS)

[Davi.p]

Re: Philips 43PFS5803

Replace mosfet first.. if it is shorted between drain-gate check components between gate and ic, get also a new ic this case..

[Sraros]

Re: Philips 43PFS5803

I found a repair kit that includes IC U9101, mosfet, blue film capacitor and the resistors (even though R9104 is not included but already replaced) so I will change them all.
Better safe than sorry, specially when my only other option is to buy separately and wait 2 months from China..
It seems this can be a common problem in this board since there’s a specific repair kit for it.
I will come back in 15 days when they arrive.

[Sraros]

Re: Philips 43PFS5803

Had the mosfet been changed before? I think one was 8A and called for 24A.

No for sure not, maybe it's another version of the original board to cut down the cost. The repair kit has the same Mosfet I removed and not the one in schematic

[Sraros]

Re: Philips 43PFS5803

Update on this. The repair kit did it's job. TV works again.

IC U9101 was indeed shorted (compared grounds to new one)
Q9101: K8A65D1 shorted
The SMD resistors passing through blown.
All the 0 resistors ok. Fuse and caps ok