Lenovo YOGA 7 14IAL7 USB-C Charge Briefly goes to 20V cyclicly.

[abajor]

I'm investigating the above mentioned Yoga 7. There's something causing it to loop in the power up phase. I can hear a ticking noise before my USB Digital Multi-meter resets.

I'm guessing it's a power mosfet? I'll update if I find anything, but if anybody experience, knowledge or info about this unit, it will be much appreciated. Thanks.

[abajor]

This is a strange one.

I disassembled The laptop and powered up the bare board, and it came to life.
I reinserted the board and slow started reconnecting components one at a time testing power up. Nothing caused the board to return to the issue of power cycling the power supply.

My best guess an intermittent connection or bad solder joint.

But it got weirder where I left it off for a couple of days, came back to it and it wasn't turning on the USBC charger/power meter at all.

Detaching the battery caused the USB to deliver 20V and power up the laptop.

The Battery also has enough charge to power the laptop.

Anybody seen behavior like this?

[mon2]

Test the voltage to ground of each pin on the battery connector. Post each measurement.

[abajor]

Test the voltage to ground of each pin on the battery connector. Post each measurement.

Installed without USB charger or with USB charger?

Both?

[mon2]

Disconnect the battery.

[abajor]

Ok well I have with and without battery and usb in.

Battery With USB:
1. RED 13.93V First measurement briefly 14.4V
2. RED " "
3. RED " "
4. Green 3.291V
5. Grey 3.291V
6. White 0.302V
7. Yellow 0V
8. Black 0V
9. " "
10. " "

No Battery USB in Laptop Off:

1. 16.2mV
2. " "
3. " "
4. 3.299V
5. " "
6. 2.97V
7. 0V
8. 0V
9. 0V
10. 0V

[mon2]

What is the raw battery voltage while it is disconnected from the logic board?

The smbus line voltages are ok on the battery connector.

[abajor]

What is the raw battery voltage while it is disconnected from the logic board?

The smbus line voltages are ok on the battery connector.

As of today 14.07V