Lenovo S145-15IL won,t charge

[Zippo978]

Measured the resistance of the mosfets

PQ103
S-D= 0.7 / 0.9
S-G= 206
G-D= 1.1

PQ104
S-D= 0.5
S-G= 197
G-D= 0.5

[mon2]

Unable to understand the measurements.

Post a link to your meter's user manual in English. There must be a way to force the meter to measure the resistance.

Resistance measurements will be in ohms.

Place one meter probe on mosfet pin #1 and other probe on pin #8. This check is the source-drain resistance. Never any power to the board in resistance mode checking.

Post the measurement and the units of measurement. Ohms, kohms, Megaohms, etc.

Or take a pic of each measurement of your meter face.

[Zippo978]

Let's see if I can borrow a tester on Monday

[Zippo978]

Repeat the measurements

PQ103

SD= 0,7 / 0,9 M
SG= 206 K
GD= 1,1 M

PQ104

SD= 0,5 M

SG= 197 K

GD= 0,5 M

I hope they go well this time

[mon2]

PQ103
SD= 0,7 / 0,9 M
SG= 206 K
GD= 1,1 M
PQ104

SD= 0,5 M
SG= 197 K
GD= 0,5 M

These measurements look low for a good mosfet. Consider to flux and remove off the board for additional testing. They may need to be replaced.

[Zippo978]

Since I have two identical cards inside, which I can use as donors, how much should those values be?

[mon2]

You can check Google for many of these articles / video tutorials on YT.

A good mosfet should offer a high resistance of Mohms.

[Zippo978]

You can check Google for many of these articles / video tutorials on YT.

A good mosfet should offer a high resistance of Mohms.

Ok, thanks.


Do I take them apart and do the same measurements?

[mon2]

Yes, flux it well -> hot air till the solder melts - be patient and protect other nearby parts with low air pressure. Parts that can melt should be shielded from the heat. Then remove off the board -> allow it to cool and test the mosfet again using the same method.

[Zippo978]

Disassembled and re-measured

S-D = 1.1M on both

I have no readings on the others

[mon2]

Check post #25 - the measurements in RED are of concern. Test those again.

[Zippo978]

I have no measurements on the disassembled mosfets.

On the motherboard without mosfet between Source and Gate I have the same values as in post 25

[Zippo978]

Sorry for my ignorance, but as I was saying I just started, I shouldn't find 9V on pin 5678 of PQ102, I understand this from the diagram.

[mon2]

Did you say that you have a working unit of the same model available for measurements?

[Zippo978]

No, only a donor board from which I have already taken some parts is not working, such as the mosfets on the primary and the bios chip

[mon2]

Measure the voltage to ground of ACOK (pin # 5) on the charger IC (PU100).

[Zippo978]

Voltage to ground of pin 5 of PU100 2.5V.

Can you tell me what Batt+ and V9B+ mean?

[mon2]

BATT+ is the junction where the battery is used as the power source. In this case, the power adapter's DCin mosfets will be OFF, the charger mosfets for the battery @ PQ103 & PQ104 will be OFF. The battery flow through mosfet @ PQ102 will be ON. This battery voltage is ~9 volts and is ample to power the logic board.

Respectively, the V9B+ is the main power rail used to power the logic board. If the main power adapter is applied, then the ~19 volts will travel through the power path, through the enabled 2 x DCin mosfets to supply the ~19 volts onto the main power rail. In this case, since the power adapter is mated to the logic board, the battery charger mosfets will toggle on/off to regulate the proper battery charge voltage using mosfets PQ103 & PQ104 to a safe voltage. The current sense resistor in this battery charge circuit is monitored for safety.

The main battery mosfet @ PQ102 will be OFF in this case since the main power adapter is powering the logic board.

[Zippo978]

Ok thanks, that's what I thought, I needed confirmation.

What can you tell me about it?

With power supply and without battery, voltage to ground of pin 5 of the PU100 2.5V.

[mon2]

See attached. Confirm if you have the 2 resistors onboard with a high side and a low side to lower the REGN voltage.

Confirm if you have ~6 volts on one leg of resistor PR112.

That is, with a 6 volt input, with PR112 & PR111, the ACOK voltage will be divided down.

Can you confirm the resistance of PR111? PR112? Remove all power / remove the battery. Measure the resistance across each resistor to measure.