Run Dell Inspiron 7620 2-in-1 aka Antman 16N ADL UMA without battery

[RainerZuf]

Hi,
I have a special question for a Dell Inspiron 7620 2-in-1 aka Antman 16N ADL UMA.
I got a defect unit and succesfully repaired it, I actually plan to use it as a server,
Sadly this mainboard is not working without attached battery, when USB C only is connected the mainboard does not start.
Ideally I would inject 12V to the batteryconnector and use it this way or alternatively use it with USB C connected.
I already tried to pull RUNPWROK up to 3.3v but it did not work.
Do you have an idea how to trick the board to run from either 12V or USB C?

Mod Edit: Link to schematic - https://www.badcaps.net/forum/troubl...06#post3450606

Many thanks!

[mon2]

Would you have a USB-C meter? It will help.

Attach the official power adapter to the USB-C port. Carefully measure the voltage to ground at +SDC_IN?

[RainerZuf]

Hi,
thanks for your reply.
Yes, sure USB C Meter is available. After negotiation to 20v, +SDC_IN is 20V also.
I measured it on the ADP Pin on the ISL9538.
When applying 12V to the batteryconnector +SDC_IN is 0V

Thanks again!

[mon2]

Remove all power. Meter in DIODE mode.

Red meter probe onto the anode (backside of the arrowhead) of diode @ PD4407. Black meter probe onto the cathode of the diode = PR4403. What is the measurement?

Reverse the meter leads and the diode should block. Confirm this detail.

Repeat with diode @ PD4401. Confirm that the diode should be blocking in reverse mode. No power to the board during diode mode testing.

[RainerZuf]

Hi,
thanks again.
Both Diodes are fines, voltage drop for both 0,235v and blocking in the other direction.
The silkscreen is not that great but i could confirm both diodes by reconstruction the circuit from the schematics.

Thanks!