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.

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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]

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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

[m1ch43lzm]

Maybe it's the same issue since the E15 gen 2
https://www.youtube.com/watch?v=7K6XsZkWzJo
https://www.youtube.com/watch?v=55oGJArv2oo

Root cause appears to be faulty PD controller not driving the MOSFET gates high enough, those 2 videos show a "dodgy" way to fix it, bypassing the input MOSFETs

[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.

Here are the latest measurements made with 30M ohm range

[Gokhant]

I shorted QB5 and QB6 out while they were in circuit and startet the laptop but it doesnt turned on. And the current consumption which were 2 amp is not there anymore. I removed the short and tried again, and still zero consumption.

[mon2]

Bypassing is a hack trick. Not recommended. If it could have been done, the factory would do the same to save pennies and increase their profits.

Suspecting that the fuse @ F6101 has triggered. Measure the voltage to ground on each side of the fuse @ F6101. Post the measurements.

After this review, solder back QB5. Replace QB6 which is conducting but should not be.

Both of these mosfets are N-channel type. For each to turn on fully, the gate voltage should be ~25v but you are @ 20v on this board. The reason QB5 passes the voltage is due to the internal diode. This is ok. Not ok for QB6 because the internal diode is in the reverse direction yet the voltage is passing through. To me, something is wrong here for this mosfet to enable with a 20v at the gate pin.

[Gokhant]

Bypassing is a hack trick. Not recommended. If it could have been done, the factory would do the same to save pennies and increase their profits.

Suspecting that the fuse @ F6101 has triggered. Measure the voltage to ground on each side of the fuse @ F6101. Post the measurements.

After this review, solder back QB5. Replace QB6 which is conducting but should not be.

Both of these mosfets are N-channel type. For each to turn on fully, the gate voltage should be ~25v but you are @ 20v on this board. The reason QB5 passes the voltage is due to the internal diode. This is ok. Not ok for QB6 because the internal diode is in the reverse direction yet the voltage is passing through. To me, something is wrong here for this mosfet to enable with a 20v at the gate pin.

One of the gates has almost 20 but the other one has 9V. So thats a obvious error. I will get back on you with voltage for the fuse

[mon2]

At 20v or 9v - both should not enable these N-channel mosfets. The first mosfet can conduct partially because of the direction of the internal diode. This is a low current diode so not enough to power the board. To properly enable each of these N-channel mosfets, the gate voltage should be ~25v. Otherwise, there is something wrong with one or both of these parts. The mosfet driver must also be capable of supplying the boosted adapter voltage of ~25v.

[Gokhant]

At 20v or 9v - both should not enable these N-channel mosfets. The first mosfet can conduct partially because of the direction of the internal diode. This is a low current diode so not enough to power the board. To properly enable each of these N-channel mosfets, the gate voltage should be ~25v. Otherwise, there is something wrong with one or both of these parts. The mosfet driver must also be capable of supplying the boosted adapter voltage of ~25v.

Totally agree on it. i have now measured the fuse and its ok, the 20V is at the both end of the fuse. i have tried to measure on many ic, and even the motherboard is consuming 0.05amp, i manage to find an IC that gets really warm, rest of the board is cold.

[mon2]

Remove all power.

Measure the resistance of PL4201 (+3VALW) to ground. Of concern is if this is a low resistance since the same rail is supplying the PCH / CPU IO pins. What is the resistance in ohms?

[Gokhant]

Remove all power.

Measure the resistance of PL4201 (+3VALW) to ground. Of concern is if this is a low resistance since the same rail is supplying the PCH / CPU IO pins. What is the resistance in ohms?

its 1.1K ohm to ground. I have also taken resistance with respect to ground, of the PU4201 , and attached and i have also noted the voltage of each pin with respect to ground.

I found that the PL7, located on the right side of PL4201, has 0 volt and 0.2 ohm to the ground where it should be : +1.8VALW