Acer aspire one not power on

[usyusy]

Acer aspire one (LA-5141P, KAV60) not getting powered-on,. Any guidance please.

Some testing are:
Rtc Crystal and IO crystal 32khz ok
3v & 5v ok, VL ok
Cmos battery removed
Before pressing, dc supply shows 0.002A
after pressing power button led on it glows for few seconds then off and board does not power-on

[mon2]

Re: Acer aspire one not power on

See attached. Review the details of PQ10 DCIN mosfet.

Post the voltages on the pins shown with the arrows.

Next, remove all power -> check the resistance across the mosfet pins.

See the many other threads here on how to test the resistance to confirm if the mosfet is defective or not.

[mcplslg123]

Re: Acer aspire one not power on

What is the consumption when u turn on? I'm interested in the variation of consumption between on and off mode. What rails are coming up and what not(after pressing power switch)??

[usyusy]

Re: Acer aspire one not power on

See attached. Review the details of PQ10 DCIN mosfet.

Post the voltages on the pins shown with the arrows.

Next, remove all power -> check the resistance across the mosfet pins.

See the many other threads here on how to test the resistance to confirm if the mosfet is defective or not.

Sir, on PQ10 DC IN mosfet:
Voltages on
Source: 19.7
Gate. 7.8
Drain. 19.7

Resistence: on 200k settings:

Drain & source 44.3 k
Source & gate 81.6 k
Gate & drain (on 2M setting): 590 k

[usyusy]

Re: Acer aspire one not power on

What is the consumption when u turn on? I'm interested in the variation of consumption between on and off mode. What rails are coming up and what not(after pressing power switch)??

Sir, when turn on (which sometime not so have to unlpug and then plug to be able to trigger)
Only 0.03A and then again on 0.02A.
Only 19v, 3v and 5v available before and after pressing power button no other voltages show on any other coil.

[mon2]

Re: Acer aspire one not power on

Replace PQ10. The resistance is too low to be a good mosfet.

[usyusy]

Re: Acer aspire one not power on

Replace PQ10. The resistance is too low to be a good mosfet.

Replaced with a scrap board mosfet

Drain & source 49.6k
Gate & source 81.6k
Gate & drain 640k

[mon2]

Re: Acer aspire one not power on

Measure the resistance of the removed mosfet while it is off the logic board.

Post the readings.

[lapfix]

Re: Acer aspire one not power on

Replace PQ10. The resistance is too low to be a good mosfet.

Why yo judge that's not perfect !!

how much will be find to be sure !

[mon2]

Re: Acer aspire one not power on

See here:

http://electronicsbeliever.com/how-t...-is-defective/

[lapfix]

Re: Acer aspire one not power on

See here:

http://electronicsbeliever.com/how-t...-is-defective/

yes i know this site , it was a nice advice from you from another thread....but still confuse , the reading of usyusy are perfect to me...did you compare it with another same mosfet or from mosfet datasheet

[mon2]

Re: Acer aspire one not power on

did you compare it with another same mosfet or from mosfet datasheet

No. Do not have these parts here but expecting a much higher resistance reading for the same measurements (100kohms++).

Since the resistance checks are similar for both parts on the logic board, the mosfet may be ok but let us wait on the OP to post the resistance values of the mosfet while it is out of circuit.

The support components on the logic board may be influencing the resistance values.

[usyusy]

Re: Acer aspire one not power on

Drain & source 44.7k
Gate & drain & source showing 1, not any movement on multimeter

[mon2]

Re: Acer aspire one not power on

IMHO - the resistance is too low for source & drain. Is it possible that the replacements were also defective ?

Would you have fresh mosfets you can test here ? Before soldering them, check their resistance while they are out of circuit.

[usyusy]

Re: Acer aspire one not power on

Replacement done with another mos

Drain & source 322 k
Gate & drain 588 k
Gate & source 197 k

[mon2]

Re: Acer aspire one not power on

Ok. What mosfet was used for the replacement ? Share the part number.

With the new mosfet, what are the results ?

What are the voltages on the source, gate, drain pins of this mosfet ?

[usyusy]

Re: Acer aspire one not power on

Ok. What mosfet was used for the replacement ? Share the part number.

With the new mosfet, what are the results ?

What are the voltages on the source, gate, drain pins of this mosfet ?

Its was Pbyhd fds 6679az something written on it, pic attached
Results are same

Voltage :
Source 19.7v
Drain. 19.7v
Gate. 7.7v

[mon2]

Re: Acer aspire one not power on

So the voltage is passing between source & drain.

Do you always see the voltage on both sides of the mosfet ? Or does it power OFF after a few seconds like before ?

What is the voltage of the main rail @ CHG_B ?

While the power rail is ON, check the voltage of each inductor to confirm that each respective power rail is working.

Report any 0 volt or low voltage rail that may be faulty.

Any liquid damage ? Just stopped working one day ? Using the original power adapter ?

[usyusy]

Re: Acer aspire one not power on

yes sir on both sides of mosfet the voltage seems always, CHG_B main rail shows 19.5v, before and after power button press only 3v,5v rails remains on no other rail appears on any inductor, board showed some carbon around IO, so washed , yes just stopped one day, using original adapter even dc supply was used.

[mon2]

Re: Acer aspire one not power on

Does the gate voltage change on PQ10 mosfet when you press the on/off button ? It should to allow for the logic board to turn ON/OFF.

The io controller may need to be reprogrammed or replaced but no experience in that area.

For the coils that have no voltage, remove all power and check their resistance to ground. This will check for shorted caps.

Post the details.

Wait on other feedback.