Alienware 17R2 dead, no power, no charging

[Tend0]

Hello everyone,
I just received an Alienware for repair, the pc seems to have been tweaked before.
I did an inspection and some components are missing. the pc does not turn on, after the tests on the main rack I have the 19v from the charger to the drain of the pq707 and to the pq701and :
PQ707 : Source= 17,46V ; Gate=19,52V ; Drain= 19,52V
PQ701 : Source= 17,46V ; Gate=19,52V ; Drain= 19,52V
PQ702 : Source= 17,46V ; Gate=14,18V ; Drain= 16,96V
PR702:16,96
I don't understand why the voltage at the main line is 16.96.
Is it because missing of pr726, pr725 and pc722 and pc723 or a leaking MOSFET? Thanks for the help have a nice day
Some images, board view and schematic in attached!!!!

[mon2]

Re: Alienware 17R2 dead, no power, no charging

Remove all power. Meter in resistance mode.

Check the resistance across the mosfet pins to see if the mosfet is shorted. A low resistance = defective mosfet.

Start with the 2nd DCin mosfet @ PQ702.

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Often, it is the 2nd mosfet that gets damaged.

Then proceed to also check the first mosfet (pair?) @ PQ701 & PQ707.

Post the measurements of each.

Also of interest are the voltage to ground measurements of the charger IC.

Meter in DC volts mode; 30v or higher is ok.

Check:

REGN ; pin 24
ACOK ; pin 5
ACDET ; pin 6
VCC ; pin # 20

Your gate voltage on the mosfets is low so suspecting that you have a leaky mosfet in the first 3.

[Tend0]

Re: Alienware 17R2 dead, no power, no charging

Meter in resistor mode; 600k
PQ702
source (1-2-3) & drain (5-6-7-8) OL
source (1-2-3) & gate (4) 103 k
gate (4) & drain (5-6-7-8) OL

PQ701
source (1-2-3) & drain (5-6-7-8) 61,6k
source (1-2-3) & gate (4) OL
gate (4) & drain (5-6-7-8) OL

PQ707
source (1-2-3) & drain (5-6-7-8) 65,6k
source (1-2-3) & gate (4) 66k
gate (4) & drain (5-6-7-8) 0,1k

Meter in dc mode; 60v
REGN ; pin 24 : 6,04v
ACOK ; pin 5 : 17,18v
ACDET ; pin 6 : 2,36v
VCC ; pin # 20 : 0,60v

Missing PWR-3.3VALWP/5VALWP IC

[mon2]

Re: Alienware 17R2 dead, no power, no charging

Some errors in measuring. Can you confirm?

VCC cannot be 0 volts if REGN voltage is 6v.

ACOK appears to be too high. Check again.

Remove pq702 and then measure the other mosfets again. Each mosfet has a low reading but may be due one bad seed in the bunch.

[Tend0]

Re: Alienware 17R2 dead, no power, no charging

Yes sir VCC is pin 28 or not pin 24

REGN ; pin 24 : 6,04v
ACOK ; pin 5 : 00v
ACDET ; pin 6 : 1,53v
VCC ; pin # 28 : 16,53v

Mosfets mesure with removed PQ702

PQ701
source (1-2-3) & drain (5-6-7-8) 56,8k
source (1-2-3) & gate (4) OL
gate (4) & drain (5-6-7-8) OL

PQ707
source (1-2-3) & drain (5-6-7-8) 400k
source (1-2-3) & gate (4) 56,2k
gate (4) & drain (5-6-7-8) 0,1k

[mcplslg123]

Re: Alienware 17R2 dead, no power, no charging

PQ707 needs to be replaced.