Lenovo ThinkVision P40w-20 no power – ILPI-422 VA board repair help

[Habble7]

Hello everyone,

I'm trying to repair the power supply board from a Lenovo ThinkVision P40w-20 monitor. The board is labeled with the following markings:

- Main PCB code: ILPI-422 VA (dated 2021/11/24)

The monitor is completely dead, no power LED or backlight. Upon inspection, I found a few components that appear damaged, particularly some resistors that are burned and unreadable.

Attached is a high-resolution photo of the power supply board.

Does anyone have a schematic, boardview, or similar power supply that can help identify the resistor values? Especially the ones near the transformer and switching section that appear to be burnt and unreadable.

Thanks in advance!

[stj]

the group of 4 are for current sensing, something connected to them is shorted out

[CapLeaker]

R834 is 0 ohm and the one above it is 20 ohm (200). All the resistors that blew have a low ohms values. The 4 in a row 2 of them is think are R220 = 0.22 ohm. The other 2 I am not sure but they either are the same or close to it.
Something shorted these resistors out,

[Habble7]

Thank you for your suggestions!
I've replaced all the burned components, including both 20N60 MOSFETs (they were also damaged). Now, nothing burns when I power the board — I'm using a 100W incandescent bulb in series as a protection load.

However, I'm getting around 300V on the bulk capacitors, but the board stays silent — there are no gate drive pulses to the 20N60 switches.

The board uses an NCP1632 controller, and I suspect it might be faulty. I've ordered a new one and will try replacing it to see if it helps.

[CapLeaker]

You have to check the whole gate drive circuit including the PWM. Verify the PWM gets power etc.
2 x 20N60's for a monitor???

[Habble7]

The 20N60 transistors are now working properly.The original factory-installed ones were faulty — I've attached a photo showing their condition. Since this monitor is quite large and high-powered, it made sense to use robust replacements.

I also replaced a shorted NPN transistor, and swapped the original NCP1632 with an SPC1012T, which I unexpectedly found on a BN44-00781A board. I confirmed compatibility by carefully comparing the pinout and operating logic of both ICs, as no official datasheet for the SPC1012T was available.

Thanks again for all your suggestions — I was able to repair this power supply board after previous repair attempts by others had failed.

[CapLeaker]

Sweet repair!