IdeaPad Gaming 3 15ARH7 - No Power or Charge

[grimacelord]

Hello,

I've been working on this laptop for a few hours and I am stumped. Still learning this kind of troubleshooting. Hoping someone can help.

Computer Information:
Model: Lenovo IdeaPad Gaming 3 15ARH7
Motherboard model: NM-E211 Rev: 1.0
Schematic, Boardview, & FlexBV Free - Attached


Problem:
The computer does not charge the battery or power on also does not power on with power adapter only. Battery have no charge on it at all (reading mV on battery charge). When connecting the power adapter through a USB-C ammeter, it reads 20V and 0.03A. The USB-C charging port is not broken. There are voltages that seem to be missing on the board and others seem to fluctuate instead of hold stable. There is no voltage at the battery connector.

Troubleshooting:
Checked for shorts at all of the large inductors and found none.
Pins 1 & 2 at the battery connector (VMB2) have no voltage when the battery and the power adapter is connected. Both sides of the fuse (PF3000) that is connected to Pins 1 & 2 also read no voltage. Fuse is not blown and neither are the other fuses on the board.
Pin 3 & 4 at battery connector (EC_SMB_CK1_R and EC_SMB_DA1) have 0.5V
VINT20_IN is not stable and reading 3.3V - 3.4V (But shouldn't this voltage be 20V?)

I don't know. If I am reading this schematic correctly, it looks to me like my problem is VINT20_IN is not being created and am I reading that voltage line correctly? It should be a 20V line, right? According to the schematic and my limited ability reading them, it seems to me like UB7 creates VINT20_IN? Is that where I should be looking?

I'm hoping someone can look at this and help me out. I'll be glad to take any measurements you need me to. Thank you.

https://www.badcaps.net/forum/troubl...-intel-nm-e211

[mon2]

I think this mosfet is leaking. Check the resistance across the pins with no power. Or just replace it to test.

At this gate voltage, the mosfet should be off. The internal steering diode may be the reason for the pass through voltage but the gate voltage should not be the same value.

[grimacelord]

So I looked at the schematic again and found power rails that should be present in S4/S5 state and measured those. Those rails are listed on page 4. Almost all of them are missing or low:

Should be present in S4/S5 state: (All taken with AC adapter only, as schematic required)

V9B+ - 0.96V
+5VL- (1mV and slowly climbing)
+5VALW - 30.8mV
+3VALW - 1.24V
+3VALW_PCH - 0
+1.8VALW - 16.8mV

With so many missing, I undoubtedly will need some help on this one. Anyone care to please take a look? Thank you.

[mon2]

Start with VINT20_IN being not stable. Often this is a clue that someone is consuming too much current and tanking this power rail.

Remove all power. Meter in resistance mode (not DIODE mode). Measure the resistance to ground of VINT20_IN. Post the measurement in ohms.

[grimacelord]

Start with VINT20_IN being not stable. Often this is a clue that someone is consuming too much current and tanking this power rail.

Remove all power. Meter in resistance mode (not DIODE mode). Measure the resistance to ground of VINT20_IN. Post the measurement in ohms.

Resistance to ground in Ohms mode on VINT20_IN measured at PL4000 reads 0L.

[mon2]

Is your meter auto-scaling for the resistance mode or manually selected for each range? If manual, shift to a higher scale till you have a measurement. OL = over limit for the selected resistance mode scale.

To summarize, if your meter is in DC volts mode, this same test point is not stable on the adapter voltage? This implies there is a fault here if the power adapter is stable when it is not plugged in.

Would you have another power adapter for testing?

[grimacelord]

Is your meter auto-scaling for the resistance mode or manually selected for each range? If manual, shift to a higher scale till you have a measurement. OL = over limit for the selected resistance mode scale.

I placed the meter in manual Ohms mode as requested. If set to auto, the measurement jumps around for moment before settling around 3.4 mega ohms and slowly falling.

To summarize, if your meter is in DC volts mode, this same test point is not stable on the adapter voltage?

Yes. Same test point. I grabbed another power adapter and repeated the DC volts test and the same component PL4000 at VINT20_IN reads 3.3 - 3.8 DCV

[grimacelord]

Also wanted to add, with a new power adapter connected through a USB-C meter, it also reads 20.2V and 0.03A just like the original adapter.

[mon2]

Check the DCin mosfets. 20V is very good and this implies the power delivery negotiations have succeeded. However, this is not the voltage that is reaching the charger IC so there is a fault in this power path.

Check the voltage to ground on mosfet QB5.

Check each pin and post the measurements.

[grimacelord]

Check the DCin mosfets. 20V is very good and this implies the power delivery negotiations have succeeded. However, this is not the voltage that is reaching the charger IC so there is a fault in this power path.

Check the voltage to ground on mosfet QB5.

Check each pin and post the measurements.

QB5:

Pin 1 - 20.6
Pin 2 - 20.6
Pin 3 - 20.6
Pin 4 - 19.59
Pin 5 - 19.61
Pin 6 - 19.63
Pin 7 - 19.63
Pin 8 - 19.63

[mon2]

I think this mosfet is leaking. Check the resistance across the pins with no power. Or just replace it to test.

At this gate voltage, the mosfet should be off. The internal steering diode may be the reason for the pass through voltage but the gate voltage should not be the same value.

[grimacelord]

I think this mosfet is leaking. Check the resistance across the pins with no power. Or just replace it to test.

At this gate voltage, the mosfet should be off. The internal steering diode may be the reason for the pass through voltage but the gate voltage should not be the same value.

Meter said to auto-scale:

Red probe on Source (PIN 1,2,3) to black probe Drain (Pin 5,6,7,8) = 3.6 Mega Ohms and dropping
Red probe on Source (PIN 1,2,3) to black probe Gate (Pin 4) = 3.94 Mega Ohms
Red probe on Drain (Pin 5,6,7,8) to black probe Gate (Pin 4) = O.L

[grimacelord]

Or just replace it to test.

This mosfet is AONR32314.




Datasheet: https://www.aosmd.com/res/datasheets/AONR32314.pdf




Here is one I have on hand AON7430:






Is AON7430 close enough to be compatible? Datasheet: https://www.aosmd.com/sites/default/...ts/AON7430.pdf

[grimacelord]

I think this mosfet is leaking. Check the resistance across the pins with no power. Or just replace it to test.

At this gate voltage, the mosfet should be off. The internal steering diode may be the reason for the pass through voltage but the gate voltage should not be the same value.

Hey! Thanks for the help mon2! I went ahead and replaced AON32314 with AON7430 because it's what I had on hand and their specs are so close (but Drain-Source and Gate-Source Voltage are identical with same pinout) and sure enough, it fixed it. Board powers on and charges battery normally now. Awesome!

Thank you so much. Marked your comment as answer.

Should I purchase a new AON32314 or should I be ok with leaving AON7430 on?

Thanks again!

[mon2]

Awesome! Very nice to hear some good news once in a while Your replacement mosfet is fine. The difference in the peak currents is miniscule. If you are shopping for new parts, consider to review the mosfets from Texas Instruments from Digikey / Mouser / TI.com website. The TI.com website will often just send you free samples with overnight delivery. Usually the parts are filled by Digikey or Mouser - just a FYI.

PS: 'I would like to thank my family...' and give credit where it is due...the above 'charger circuits sticky' by piernov.