Lenovo E580 no power

[Inforgalaxie]

Hello I have this Lenovo E580 and i change the pwm and also pq102 but i have no valid gate power to arm the pq102 mosfet...just have 2.2v and must be more then 20v...
PWM have 20V ACIN, and 6V REG
What you think can be?

[mon2]

Re: Lenovo E580 no power

This charger IC will be switching the mosfets @ PQ102 & PQ101 on/off to 'dial' up the voltage required for the operation of the logic board.

The target voltage should appear @ B+ = VSYS pin # 22 on the charger IC.

What is the final voltage to ground of B+ ?

The gate voltages for each of these mosfets will be switching at high speeds so a standard multimeter will not be able to monitor the voltage. You will need an oscilloscope to view the switching action of the gate pins.

If B+ is too low, remove all power and measure the RESISTANCE to ground of B+ pin.

What is the measurement? If the resistance is too low then there is a shorted component on this main power rail.

[Inforgalaxie]

Re: Lenovo E580 no power

PIN 22 have 1.96V

[mon2]

Re: Lenovo E580 no power

Remove all power. Meter in resistance mode.

Measure the resistance to ground of B+.

[Inforgalaxie]

Re: Lenovo E580 no power

20M ohms

[mon2]

Re: Lenovo E580 no power

If the battery is attached, remove it and test this power rail again.

Suggest to remove all power, meter in resistance mode.

Check the resistance of all mated mosfets in this region as follows:

source & drain
source & gate
gate & drain


Check PQ101, PQ102 and PQ103.

Post each measurement. Checking for a low resistance = defective mosfet.

[Inforgalaxie]

Re: Lenovo E580 no power

PQ101 was the problem, 1.8 ohms resistance to ground. We found the problem.