Lenovo Ideapad 3 NM-D031 not booting no power LED.

[ShadowNX]

Hello,
I have been trying to figure out what is wrong with this laptop. None of the ICs get any voltage besides the BQ24780SRUYR. There is 20V on the drain of the main mosfet, PQ100 in boardview, but I am not finding the any voltage going to the LV5116A which if I'm reading this right, sends out the signals for the +1.8v, +2.5v, +1.2v, and +0.6v rails. I've also looked for the LV5083A and I don't see it on this system and have also eliminated LV5095B and UP1666Q as this system does not have discrete graphics.
So any advice on this, or next things to look at, so i can get it back up and running for my daughter I would appreciate it.

[mon2]

Measure the voltage to ground on the charger IC for the following pins with only the adapter:

ACN
ACP
ACDET
REGN
ACDRV
VCC. ; ~19v ?
BATPRES#

[ShadowNX]

Here is the readings off the charging chip:
ACN: 0v
ACP: 0v
ACDET: 2.8v
REGN: 6.012V
ACDRV: Varies from .011 to .12v
VCC: Between 19.79 and 20V
BATPRES#: 0v

[mon2]

Remove all power. Meter in resistance mode. Measure the resistance to ground of ACN. Testing if there is a short on the main power rail.

This may be a common fault linked to the DCin mosfets. My schematics show PQ100 & PQ101 in the power path.

Remove all power. Meter in resistance mode. Measure the resistance across the same 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. Repeat for each of the dcin mosfets. As per the charger bible by piernov (see above sticky), often the 2nd DCin mosfet is defective which takes out the first dcin mosfet since they share a common ACDRV voltage.

Each resistance measurement should be hundreds of k ohms or higher else is a suspect. If in a rush, you can flux and replace the first 2 dcin mosfets but first confirm the resistance to ground of the main power rail. If too low of a resistance then something else is wrong. You can source the DCin mosfet replacements from donor boards or purchase new ones from Digikey / Mouser. Shout back if you require links for replacements.

[ShadowNX]

This is what I got off these mosfest
PQ100
source & drain: 328K
source & gate: 374k
gate & drain: 500k

PQ101
source & drain: 437K
source & gate: 374K
gate & drain: 449K

but if sometimes the readings of PQ101 was
source & drain 35
source & gate: 374K
gate & drain: 145K

it just depended on how i was probing the source and gate with my meter.

However, I checked some more and PQ3803 to PO3805 had some readings I'm going to look into some more tomorrow as its getting late for me, but if you have the link for the PQ10x and PQ380x i would appreciate it.

[mon2]

Flux & remove PQ101 off the board. Then power up again without this mosfet. Measure the voltage to ground on the first DCin mosfet @ PQ100. Do you see a higher voltage on the gate pin # 4 = ACDRV? On a working board, ACDRV = adapter_voltage + REGN voltage = ~25v.

[ShadowNX]

I was not able to get the mosfet off today. I will either attempt again Wednesday. or it will have to wait till this coming Monday when I have access to a better re-work station. Heck it may end up being both a retry on Wednesday and then Monday because I do want to know.

[reformatt]

Have you checked for a short to ground at the current sense resistor PR100? BQ IC will switch off the input FET's in that event. This is the first thing you check.

[ShadowNX]

Ok i checked for a short to ground on PR100 but after I took of the mosfet because I did not chec the post before hand. So first thing first, removing the mosfet PQ101 did allow 25.9V at pin. 4 of PQ100.

Now measuring resistantce from both sides of PR100,if i go with the lowest readings that I got on both sides it was 0.3 and 0.4 so there may be a short and im wondering if its not PQ102 because its reading are low.

PQ102
Source to Drain: 4.2k
Source to gate: OL
Gate to drain: 435k

But that appears to be on so if i switch it off, I get
OL, 500k and 434k. And readings on PR100 are now 40 and 16.9.

[mon2]

PQ102
Source to Drain: 4.2k
Source to gate: OL
Gate to drain: 435k

This part is most likely defective. Flux and remove / replace and test again.

[ShadowNX]

Tested PR100 again after PG102 was removed and got 35 and 82 ohms.

[ShadowNX]

Can I get the Digikey and Mouser links for PQ101 and PQ102 so I can order but I will also look into some more passives as I noticed one cap that looked like its end plating was missing. Now it still made contact but still going to replace it

[ShadowNX]

Well Gents I appreciate the help with this. I found the issue I think. it was mosfet PQ9801 because testing around for shorts to ground I found that P_VDDQ_VIN_S was only 7 Ohms to ground. This was initially from a cap that had a bad end while looking closer, using a 15x loupe as I dont have a a microscope yet(on my list to get), and it was only around 6 Ohms. So going along that line, I tested every component that and all read the same approx. That's when I started tested the mosfet in question,
Source to Drain: OL
Drain to Gate: OL
Source to Gate: 45 Ohms

So I removed the mosftet and then tested PR100 again after the board cooled down. 1.2M and .7M.
Now PQ101 andPQ102 are still off the board as well.
I've been looking for those parts and cannot find them and would appreciate help getting the links for these mosfets so I can get them as well as the caps that are missing the ends, which I have found.

[mon2]

PQ101 = AONR32340C (N-channel; 3*3mm size).

Replace with: AON7528

https://www.digikey.ca/en/products/d...gFtiHDQ8LmYJIA

PQ102 = AON6324 (N-channel; 5*6mm size).

Replace with: AONS32304

https://www.digikey.ca/en/products/d.../9974867

[ShadowNX]

What about PQ9801 as that is the one that has i know 100% is shorted< because even off the board it still reads a low source to gate resistance?
And thank you for the other part numbers because i may just order those as well.
Once I get this system up and running I going to look into a Sager system and a ASUS system just have not decided which one first. but i guess that depends on which power cord I can find after moving so not everything has been unpacked yet.

[ShadowNX]

I just went over my notes and PQ101 and PQ9801 are the same mosfet models, so I already have that answer. Where can I find the match for the others if I need them:
AON7380, AONS32314, and AON6380?

[mon2]

AliExpress.