Lenovo E15 - NM-E211 doesnt turn on

[Gokhant]

Hi all,
Im trying troubleshoot a Lenovo E15 which is not turning on.
Charging Led is ON when charger plugged in.
PC doesnt turn on when pressing on button.
Sometimes on button blink 3 times and shut off and repeat it sometime again.

I took the motherboard out , and connected my in-line dc-meter and it shows 20.16V and 0.00A which for me sounds correct as there are nothing connected , not even battery.

With everything connected to the motherboard, in-line-dc-meter shows 20.09V and current consumption of 2.1Amps.

In-line dc-meter restarts like once in every minut.

PQ4000 is warmer then the rest ,you can easily hold your finger on without burn.
QB5 and QB6 has 20.02V in and out.
J5 shows 5.14V


Any advice on how i should proceed with this?

[Gokhant]

Here are som measurements

[mon2]

QB5 may be in trouble. The reason being that the gate voltage is almost the same voltage as the source / drain voltages.

If the mosfet is a P-channel type, the voltage should not pass through since the gate voltage is not low enough to enable the mosfet.

If the mosfet is an N-channel type, the voltage should not pass through since the gate voltage is not boosted enough over the 20v on the source / drain pins to enable.

The only way for the voltage to pass through will be due to the direction of the internal diode.

Remove all power. Meter in resistance mode. Measure the resistance on the QB5 mosfet:

source / drain
source / gate
gate / drain

Post each measurement. Each should be hundreds of k ohms or higher else the mosfet may be defective and must be replaced. Confirmation should be done by fluxing and removing QB5 and then measuring again while it is on your work bench.

[Gokhant]

QB5 may be in trouble. The reason being that the gate voltage is almost the same voltage as the source / drain voltages.

If the mosfet is a P-channel type, the voltage should not pass through since the gate voltage is not low enough to enable the mosfet.

If the mosfet is an N-channel type, the voltage should not pass through since the gate voltage is not boosted enough over the 20v on the source / drain pins to enable.

The only way for the voltage to pass through will be due to the direction of the internal diode.

Remove all power. Meter in resistance mode. Measure the resistance on the QB5 mosfet:

source / drain
source / gate
gate / drain

Post each measurement. Each should be hundreds of k ohms or higher else the mosfet may be defective and must be replaced. Confirmation should be done by fluxing and removing QB5 and then measuring again while it is on your work bench.

$$$$$$$$$$$$$$$$$
Thanks for the reply. I have now measured and ohm and diode mode measurements are ok. Please see attached pic. I think i should follow why the gate voltage is so low. As you mention, the gate should be higher

[lapfix]

$$$$$$$$$$$$$$$$$
Thanks for the reply. I have now measured and ohm and diode mode measurements are ok. Please see attached pic. I think i should follow why the gate voltage is so low. As you mention, the gate should be higher

Upload your schematics or BRD to give you more help
As mon2 mention before , we don't know the type of QB5 , N or P channel !
Post all the voltages of your charger circuit too

[lapfix]

Just using search at this forum
Schematics and BRD
https://www.badcaps.net/forum/troubl...-intel-nm-e211


Look at P 51 / 89

[khaahk]

Different mainboard but same case:

https://www.youtube.com/watch?v=ju6BG40l1xE

[Gokhant]

Upload your schematics or BRD to give you more help
As mon2 mention before , we don't know the type of QB5 , N or P channel !
Post all the voltages of your charger circuit too

I have attached a picture of the QB5 & QB6. Both are of the same chip which is a N channel mosfet. SM3313

[mon2]

Ok. Remove all power. Repeat resistance checks but use other resistance scales to get a reading. OL = over limit and means the resistance is higher than the selected resistance scale. Post an updated list of measurements.

[Gokhant]

Ok. Remove all power. Repeat resistance checks but use other resistance scales to get a reading. OL = over limit and means the resistance is higher than the selected resistance scale. Post an updated list of measurements.

Of QB5 & QB6?

I measured them last but all gave OL .

Whats expected levels that i can seek for when i measure?

Thanks