Lenovo S145-15IL won,t charge

[Zippo978]

I don't have PR111 and PR112

[mon2]

Ok. The '@' in the schematic denotes these then as no-stuff parts.

Continue to search for the mosfet @ QE4402. Measure the voltage to ground on each of the pins on this part.

Also interested in the voltage to ground on each side of RE4456. Confirm the voltage to ground of +3VL. Also check +3VLP.

[Zippo978]

Ok. The '@' in the schematic denotes these then as no-stuff parts.

Thanks I didn't know that

QE4402 not present

RE4456 pin1 = 3V, pin2 = 2.5V

+3VLP measured on PU9700 pin5 is present

[mon2]

Remove all power and confirm the resistance across RE4456

[Zippo978]

98.7K

[mon2]

Good resistance. Odd that the voltage is only 2v5 on the ACIN# junction.

Once the charger IC is OK with the adapter voltage, this line should float like an open switch. At that point, this pull-up resistor should soft park through the ~100k ohm resistor to +3v.

[Zippo978]

I noticed that when the PC is turned on with the battery and charger, Windows shows the symbol of the battery charger inserted and says "Battery powered" and the battery does not charge. Can it help?

[mon2]

Carefully flux and remove RE4458. Do not lose this part. Then power up again and measure the voltage to ground of ACIN# signal. You should see ~3 volts here.

[Zippo978]

I don't have RE4458, but where the tip is I have 2.5V.



see you tomorrow

[mon2]

I see - they have shorted the PCB with a trace between pins 1 & 2 on QE4402 to replace the 0 ohm resistor.

Remove all power & no battery. Meter in diode mode. Red meter probe to ground. Black meter probe to the same point as above. What is the diode mode measurement?

[Zippo978]

5.10

[Zippo978]

I found the diagram of the charging IC, PU100, and checking the voltages I realized that the ACDRV(pin4) should be 6V more than the battery charger, 26V in my case, but both with and without battery it is always 20V. I also tried turning on the PC with and without the battery and it works in both cases.

[Sephir0th]

What a shame. 52 Posts with all this mess and finally it turns out being a shorted DC-IN Mosfet.

Since you stated both of these were replaced, I have to assume you replaced them with wrong model, soldered them with the wrong orientation or something else serious happened.

However, 19 or 20V at Gate Pin is per 99,9% a shorted DC-IN Mosfet. This exact issue is well known causing the battery not charging.

Move on and confirm please.

[Zippo978]

You're right, 52 useless posts.
I replaced them and tested them and they worked perfectly, now testing PQ100 and PQ101 again the source and gate are shorted, now I'll change them again and let you know.

[Zippo978]

All resolved, a mosfet was faulty.

Thank you for your help and above all for your patience. I learned new things and in the end this is more important than the repair itself. Thanks again

[Sephir0th]

You're welcome