Lenovo IdeaPad Slim 3 15IAN8 won´t power on after power off without AC charger plugged in

[WTFRules!]

Hi!

I´ve this Lenovo IdeaPad Slim 3 15IAN8 with mainboard (KS480 / KS580) NM-E901 Rev 1.0
I receive it for repair from another shop and it had shorted EC IT8227VG-256
After replacing it and programming it with SVOD 4 (wich is new to me as I bought it in this week) the laptop is working fine now... BUT

Once power off from windows, it will not turn on again. When off and the power on button is pressed, a white led turns on and that´s it.
But if you plug the charger, then all the keyboard LEDs will lit and then you get image on screen and it boots normally.
After this, you can use it with battery normally, if you restart it, it restarts fine, and if you close the lid and open it back, it still works like a charm.

The problem is turning it off and then back on with battery, you only get a white LED on near the power button. Plugging the AC charger back again, it will make it turn ON like nothing happens.

I´m attaching a boardview I got from this forum as reference as i don´t have the schematics. Link to boardview -> https://www.badcaps.net/forum/troubl...04#post3648504

All measures from battery seems fine.
No shorts detected.
Also I updated UEFI firmware and ME from latest files from LENOVO, the issue remains the same.

Any help is appreciated.


Thanks!

[WTFRules!]

Well, thanks to the approach of mon2 I think I gave a solution to this problem.

I just added an extra diode between pin 2(CHARGER_IN) and 3 (BATT+) of diode (PD5400) mentioned in previous post, using the battery voltage to "make believe" to this part of the circuit that the AC charger is connected, wich is not.
This way faking that is connected to the charger all the time, now I can turn on the laptop just with the battery.

The charger LED status works fine, being OFF without the real charger and ON with charger plugged in. And changing from ORANGE when really charging the battery to WHITE when done charging the battery.

I hope this may help who have a similar issue like the one I experienced with this notebook.

I´m attaching a picture.

Thanks you all!

[mon2]

Review the dual diode that often feeds the vcc pin of the charger ic. Usually on the BQ chips, this dual diode will have one leg to the battery and other to the raw adapter voltage. Confirm this dual diode is not defective.

[WTFRules!]

Review the dual diode that often feeds the vcc pin of the charger ic. Usually on the BQ chips, this dual diode will have one leg to the battery and other to the raw adapter voltage. Confirm this dual diode is not defective.

Hi,

Thanks for the help!
I just checked the diode (PD5400) BAT54CW and it´s OK, not shorted and working as expected.

With battery connected, diode pin 1 (CHG_VCC_R) have 12.5V from battery going thru 10 ohms resistor (PR5431) to pin 28 of IC BQ24780S (CHG_VCC) and in diode pin 2 (CHARGER_IN) have 0.8V and goes thru 44.7K (PR5432) resistor to the BQ24780S IC pin 6 (CHG_ACDET)
When AC charger is plugged in, diode pin 2 goes up to 19V from diode pin 1 too, and at BQ24780S IC pin 6 (CHG_DET) gets 2.4V.

Seems working fine.

Anything else that I can check?

Thanks!

[WTFRules!]

Well, thanks to the approach of mon2 I think I gave a solution to this problem.

I just added an extra diode between pin 2(CHARGER_IN) and 3 (BATT+) of diode (PD5400) mentioned in previous post, using the battery voltage to "make believe" to this part of the circuit that the AC charger is connected, wich is not.
This way faking that is connected to the charger all the time, now I can turn on the laptop just with the battery.

The charger LED status works fine, being OFF without the real charger and ON with charger plugged in. And changing from ORANGE when really charging the battery to WHITE when done charging the battery.

I hope this may help who have a similar issue like the one I experienced with this notebook.

I´m attaching a picture.

Thanks you all!

[mon2]

Cannot argue with success. Sometimes the 10R ohm resistor becomes defective. Glad that you have it working.