Acer Predator Helios 300, FH52M LA-J891P REV.1 A No Power

[Tend0]

Mainboard ; FH52M LA-J891P REV:1 A

Hi everyone happy new year to all

I try to fix this motherboard no power missing 19v
the first DCIN PQB11 mosfet receiveide 19v in drain.
the test i have done :
Mosfet PQB11 and PQB12 check and change still have no power
Charging IC PUB1 check step:
-VCC pin 28 = 19V
-ACDET pin 6 =2,62V
-REGN pin 24 = 6V
-CMSRC pin 3 = 0V
At this step i replaced IC but still problem no voltage in gate on 2 dcin mosfet
What i missing?

the schematic in below
Thanks
I use Rev:0.1 schematique and boardview
https://www.badcaps.net/forum/troubl...atic-boardview

[mon2]

Hello and the same to you.

First, in the future, best to post the schematic and BV files in the dedicated schematics sub-forum. Posting here will get you immediately removed from @SMDFlea's Christmas cookies list.

Does your logic board also have stuffed the mosfets @ PQB18, PQB19, PQB3? Each is a suspect.

Best to test each of these DCin mosfets using resistance mode. Remove all power. Meter in resistance mode.

Measure the resistance across each mosfet:

source / drain
source / gate
gate / drain

Each measurement must be in hundreds of K ohms or higher else could be defective / leaky.

Without power, measure the resistance to ground of the main power rail @ ACN / ACP on the charger IC. If this rail is too low of a resistance then the charger IC will detect this fault using the ACN / ACP pins and will turn off the DCin mosfets by keeping ACDRV low / 0 volts. ACDRV must be ~25v to enable the DCin mosfets.

Post each measurement. As a quick test, you can remove the above noted mosfets to check if ACDRV returns to a normal value of ~25 volts.

[Tend0]

Thank for suppor, ok i understand in futur i avoid it

No PQB18 and PQB19

Mesure resitances of each mosfet:

Calibre: 600K

-PQB11
source / drain :576 K
source / gate :591K
gate / drain :105K


-PQB12
source / drain :107 K
source / gate :107
gate / drain :

-PQB3
source / drain : OL
source / gate : OL
gate / drain : OL

Circuit charger IC mesurement without power:
ACN:0.0k
ACP:0.0k
When noted mosfet remove ACDRV have 2.62V

[mon2]

The resistance to ground of ACN is 0 ohms? This is a direct short.

The MOSFET measurements are low.

Flux and remove MOSFET PQB12. Power up without PQB12. What is the voltage of ACDRV?

[Tend0]

ACDRV = 0V

[Tend0]

yes resistance to ground of ACN is 0 ohms

[Tend0]

Thank mon2 PQB12 was leaked after remove it the gate of dc IN recover her 25V, after replace pqb12 there was short to ground due faulty to PQW1 then i remove and computer power on now. i will order and replace it. thank so much for helping

[mon2]

Well done! The updates are appreciated and will help future readers.