BN44-00472A power off loop

[case sensitive]

Hi I have a Samsung BN44-00472A from a UE32D4003BW.
The TV didn't power on and I found that ICM801S (STR-W6053S) was shorted and the fuse FM801S had blown so I replaced both of those.
The board now powers on for around 1 second then there is a click and it powers off, this repeats until AC power is removed.

I've checked the main rails on the cold side and resistances to ground look sensible:
B13v / Vamp: 23K
B5v: 216 ohms (schematic shows a 220 ohm resistor connected between it and ground)
A5v: 1.5M and falls slowly
Vdrv: 6M and falls slowly
PS-ON: 65k
PWM_DIM / EPWM: 6.5K
BLU_ON: 6K
13v1: 880K
DRV_OCP1: 67K
DRV_OCP2: OL
PWM_W1: 7.5K

I'll power it on later and double check voltages but from what I remember they all seemed OK for the short time they are up.
I think DRV_OCP1 was around 2.5v (comes from SEM5025 fail pin) so I assume the problem is something to do with that.

Schematic attached, will upload board photo when home later.

Any ideas what might cause this?

[Chungalin]

I’m stuck in the same place. In my case, it’s a very similar BN44-00471A from a UE26D4003BW (I’m actually using schematic for BN44-00472A and I’ve found minimal differences). All voltages fall every second. I disconnected all supply to the backlight driver and then it turns on without problem (A5V, B5V, B13V OK). But as soon as I power the backlight and I connect DRV_OCP1 (without LED strips connected), the problem comes again. It seems that IC SEM5025 rises FAIL pin to 5V every two seconds, and I still haven’t found anything bad or shorted. Checked all MLCC around it.

[Chungalin]

I’ve eventually repaired it, although not on my own merits. DRV_OCP1 wasn’t a problem after connecting the LED strips. If you disconnect Main board, the PSU turns on by default and the backlight works at max brightness. The problem arised from DRV_OCP2 after connecting MAIN board. I found a blog (Kent Liew LCD repair) that explained a very similar case with BN44-00472A. He found that the culprit is QQ9101 (MMBTA92, marking 2D or YV, depending on manufacturer), that is responsible of raising DRV_OCP2 protection. My transistor tested normal, but I tried to replace it anyway. Now it works!