Asus E203MA

[Sudoer]

Won't turn on. On laboratory power suply (LPS) 0.030A appear and disappear. Input mosfet (PQ8901) won't open. Replaced capacitors and resistor. Nothing. No short-circuits.

[mon2]

Re: Asus E203MA

Hi.

Share pics of the parts in this area. Post markings on the mosfets.

Nearby the front side mosfets will most likely be the charger IC for the unit. Asus schematics are guarded very well so will have to review by example based on your details.

Once we know the charger IC markings, we should be able to locate reference or other schematics that use the same IC to learn about this design.

To check the mosfet(s), remove all power. Meter in lowest resistance mode.

Using the datasheet for the mosfet, review the resistance across:

source & drain
source & gate
gate & drain

pins on the mosfet. If you find very low resistance readings, the mosfet is likely defective. The next step is to desolder off the logic board and then test the mosfet again, while it is off the board.

[Sudoer]

Re: Asus E203MA

Thanks for the quick response. Sorry for taking so long.

source & drain = 20 MΩ
source & gate = 1 MΩ
gate & drain= 1.1 MΩ

Charger pwm is BQ24780S. Replaced just for case.

[Sudoer]

Re: Asus E203MA

Nearby the front side mosfets will most likely be the charger IC for the unit. Asus schematics are guarded very well so will have to review by example based on your details.

O

The bottom side. The charger IC is there. Anyway, by the boardview this chain (DC jack - capacitors- mosfet - charger) checked twice. Looks OK, but doesn't work.