Lenovo IdeaPad 3-15ADA05 Not Charging

[Kambi13]

Hello all, need some help on a Lenovo Ideapad 3 in wich the battery is not charging. Weird thing is the light on the power button flashing.
At what voltage should the battery charge? I'm measuring 4.1v at the current sense resistor near the battery connector.

[mon2]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

What is the voltage of the battery? Read off the markings.

[Kambi13]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

7,6v 4510mAh

[mon2]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

So it is not charging.

Locate the mosfet mated with the battery connector. Read off the topside markings.

Also locate the charger IC. What are the topside markings on the charger IC? Is it the 'BQ' style?

If the mosfet is N-channel, the gate voltage needs to be higher than the source / drain voltage. If P-channel, gate should be lower than source/drain.

[Kambi13]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

The Mosfets are all n-Channel - 1x4513NH + 2x3W0E05 (according to the schematic it's AON7380 in a 3x3mm package)

PQ203
Gate - 4.37V
Source - 4.37v
Drain - 20.39v

PQ205
Gate - 4.41V
Source - 4.41v
Drain - 20.39v

PQ206
Gate - 182.6mv
Source - 0.2mv
Drain - 4.42v

IC Charger BQ24780s

[mon2]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Do you have a schematic for this logic board? If yes, can you link it or post it?

Being N-channel, the gate needs to be boosted to enable this mosfet. Trace the gate pin of each mosfet and locate a possible series resistor that will lead back to the charger IC. Need to know the charger IC pin.

You should also review the ACDRV boost voltage. There is a usual 4k ohm series resistor on ACDRV. This line needs to be boosted to turn on the N-channel dcin mosfets. If it is low, remove the series resistor but do not lose it.

Then power up again, do you see ~25v on ACDRV now?

[Kambi13]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Here's the schematic

[mon2]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Very helpful.

Attach the battery and measure the voltage to ground of pins 3 & 4 of the battery connector.

On the battery, what is voltage of BATT+ ? This rail powers the logic board.

[Kambi13]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Pin 3 - 5.6mv
Pin 4 - 5.4mv
BATT+ 25,7mv

Weird stuff now the laptop shut itself off and wont turn on again. Main power rail is out
First Power Mosfet PQ201 at the source now measures 59.5mv?! instead of 20v

[mon2]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Pin 3 - 5.6mv
Pin 4 - 5.4mv

These are low but likely linked to the missing main 19 volts.

Start with the 2 x DCin mosfets. You should have the initial 19v at the power connector - confirm it.

Apply this adapter -> confirm the 19v on the first mosfet. Also measure the voltage on each of the mosfet pins (source / drain / gate). Being n-channel, if GATE is not ~25 volts, the mosfet will be OFF. This gate pin is driven by the ACDRV pin of the charger IC through a 4k series resistor.

Often, the 2nd n-channel mosfet gets killed.

[Kambi13]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Yes I do have the 20v at the DC IN, first mosfet has the 20v at the drain , but only 58mv at the source and gate.
2nd mosfet 112mv at the gate and 55mv at source. Drain 1.3mv

ACDRV with or without the 4k resistor has 64.4mv

[mon2]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Review the voltage on REGN pin of the charger IC.

It should be ~6volts.

Likewise, ACDRV will only be boosted if REGN is this voltage.

Post your measurement. If ok, then remove the 4k resistor on ACDRV pin. After you remove it, the ACDRV should be ~25v. Do not lose the resistor.

[Kambi13]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Ok I'll post it tomorrow, but I have the feeling that BQ24780s IC Charger is bad

[mon2]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Often, the REGN will be ~6 volts which is the boost voltage for ACDRV.

That is, the input adapter voltage of 19V + 6 volts = ~25 volts for ACDRV.

The ACDRV may be low due to the shorted mosfet that is the 2nd one in the power path. As per above article from @Piernov.

You can also remove the 2nd mosfet to test again which is the next step

OR

remove all power and check the resistance of the 2nd mosfet to see if it shorted.

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. If you happen to have a n-channel spare - replace it and check again. After the above, yes, consider to replace the BQ charger IC but it is not commonly required.

[Kambi13]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Hi mon2, good news, laptop is back online and fully charged. BQ24780s was faulty. I found out that there was some corrosion underneath the chip and also on D22 wich is a voltage supressor (AZ5123-01F), that is connected to Caps Lock light, which is now not working and also Numlock light. Do you think if it is ok to put in a 0 ohm resistor, bridge it or replace it with a filter

[mon2]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Good.

See attached. The diode @ D22 and others in the posted partial schematic are ESD transient devices that will be not active till there is a transient (surge). At that point, they will shunt the voltage spike to ground and often short circuit.

Respectively, you DO NOT bridge / short these pads. These are devices that camp on the signal rail and jump in to protect the line if there is a nasty surge voltage event.

Also note the '@' suffix which often means the part is NOT stuffed during PCB assembly time. Are you sure there were these parts even on your logic board.

A nice to have is to apply them if available but they will not stop the board from working. Each of these keyboard signals are ACTIVE LOW (noted with the '#' suffix = ACTIVE LOW). So if the line is LOW, the light should turn ON.

What voltage to ground do you read @ CAPS_LED#_R ?

[Kambi13]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

It's 3.34v, and yes it was there, because I was trying to remove the corrosion and it broke in half

[Kambi13]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Well, in the end was the keyboard ribbon cable, it comes from factory with a very hard bend and coming from underneath the battery, removed, cleaned and now everything seems perfect.
I figured out that D22 wasn't needed in order for the board to turn on, I just thought it was related to CAPS light in the keyboard to light up

[mon2]

Re: Lenovo IdeaPad 3-15ADA05 Not Charging

Well done! The ESD device is nice to have to suppress any possible ESD transient from the keyboard use, etc. Anything dealing with human touch = carpet static build up charge(?), etc. are potential risks to the logic board.