Lenovo 100-15idb NM-A681 no turning on

[xRaPiDxX]

Hello, laptop is not turning on. Motherboard Mark: NM-A681 rev 1.0 UMA
Here are the measurements I've taken:
PR301:
2.2mohm and goes down

PQ301:
S: 19.59V
G: 19.575V
D: 20.1V

PQ302:
S: 19,594V
G: 19.576V
D: 0,0022V
Diode test: 0,5341V
I don't have short circuit between S and G.
What should I measure next? Please help
Greetings 😁

[Vesko356]

Re: Lenovo 100-15idb NM-A681 no turning on

lenovo ideapad 100 CG410/CG510 NM-A681 Schematic and BVD

https://www.badcaps.net/forum/showth...37#post1044937

.

[mon2]

Re: Lenovo 100-15idb NM-A681 no turning on

Remove all power -> meter in resistance mode.

Measure the resistance between the following pins on each of the above mosfets:

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


Post each measurement.

[xRaPiDxX]

Re: Lenovo 100-15idb NM-A681 no turning on

Thanks for reply. I checked signal ACOFF and there is 0v. I measured on 98 pin od kbc, so do I need to replace KBC? I still learn.

[mon2]

Re: Lenovo 100-15idb NM-A681 no turning on

Can you link or post the schematic? The above mosfets, are not enabled. If they are N-channel type, then gate voltage must be boosted to ~25v to enable. If P-channel, gate must be lower than the source / drain voltage.

The charger IC will decide when to enable or not.

Post the schematic link. Then post the resistance checks after removing all power. Checking if the mosfets are defective.

[xRaPiDxX]

Re: Lenovo 100-15idb NM-A681 no turning on

PQ301:
Source - drain: 0.623mohm
Source - Gate: 0.1955mohm
Gate - drain: 0.44mohm

PQ302:
Source - drain: 0.27mohm and goes to 1mohm
Source - Gate: 0.195mohm
Gate - drain: 0.43mohm and increase to ~1mohm

I use schematic and boardview from this post:
https://www.badcaps.net/forum/showth...37#post1044937

[mon2]

Re: Lenovo 100-15idb NM-A681 no turning on

Check the voltage to ground of PACIN.

[xRaPiDxX]

Re: Lenovo 100-15idb NM-A681 no turning on

Voltage to ground PACIN: 3.26V

[mon2]

Re: Lenovo 100-15idb NM-A681 no turning on

Locate PQ307B. Check the voltage to ground of pins 3, 4 and also 5. Post the readings.

[xRaPiDxX]

Re: Lenovo 100-15idb NM-A681 no turning on

Pq307b:
3-0.0234v
4-gnd
5-0.0086v

[mon2]

Re: Lenovo 100-15idb NM-A681 no turning on

Check the voltage to ground of pq998.

Next, remove all power. Meter in resistance mode. Check the resistance across pr309.

[xRaPiDxX]

Re: Lenovo 100-15idb NM-A681 no turning on

Voltage to ground PQ998:
1-0.0086V
2-0.035V
3-GND

PR309- 31.82kohm

[mon2]

Re: Lenovo 100-15idb NM-A681 no turning on

Check the voltage to ground of pr309. Check both sides.

[xRaPiDxX]

Re: Lenovo 100-15idb NM-A681 no turning on

PR309
Pin 1 (PACIN) - 3.263V
Pin 2 (PACIN_G) - 0.0086V

[mon2]

Re: Lenovo 100-15idb NM-A681 no turning on

Remove all power. Check the resistance to ground of pin #2 of pr309.

[xRaPiDxX]

Re: Lenovo 100-15idb NM-A681 no turning on

Pin #2 of PR309: 128.30ohm

[mon2]

Re: Lenovo 100-15idb NM-A681 no turning on

Flux and remove pq998. Then check the voltage again on each side of pr309.

[xRaPiDxX]

Re: Lenovo 100-15idb NM-A681 no turning on

After removing pq998:
PR309:
1-3.259V
2-0.0086V

[mon2]

Re: Lenovo 100-15idb NM-A681 no turning on

Something is wrong in this region. Flux and remove pq307. Then check the voltage again on each side of pr309. The resistance to ground on the gate pin should not be so low.

[xRaPiDxX]

Re: Lenovo 100-15idb NM-A681 no turning on

After removing PQ307
1-3.32 voltage to ground, 100.67kohm (no power)
2-3.309 voltage to ground, 147.77kohm (no power)
So do i need to find and replace PQ307?