820-0840 5v 0.1A power bounce 1 sec.. ( Works with battery BMS disconnected. )

[KC Micro Tronix]

This is strange......
Machine will show 5v on the USBC meter and read 0.01A for a second and reset.

When I disconnect the BMS the unit powers up and works! ( J6951 )
With the battery BMS connected it just bounces and resets. ( I have changed the battery using a tester and get the same result! )

I diode checked SMBUS_SMC_5_G3H_SDL / SCA and both are normal
I checked SYS_DETECT_L it also appeared normal

History on this system.
It was serviced by another technician for screen replacement. They changed the screen and this was the result. The original screen is back on and does function with the same defect it had before ( lines across the bottom of the screen ) and works normally if the BMS is disconnected.

SMC? What the heck?

 

[2informaticos]

Post PPBUS_G3H exact voltage, w/ and w/o battery connected.
Did you find correct communication signals with o-scope on battery bus?
SYS_DETEDT_L stays low?

So the same board stays on (bad LCD image) with original screen assembly?
But the board doesn't turn on with new screen?

BTW, BMS is inside the battery; if you think about Battery Management System.

 

[KC Micro Tronix]

The Battery was replaced temporally with a new one and the board had the same fault. If the BMS ribbon is connected it will not post.
The fault is the same regardless if the screen is attached or not.

 

[2informaticos]

Actually, machine boots with battery connected, but then gets only lines on internal screen?

What happens if you connect battery data cable, without battery power connector?