Dell XPS 13 9370 no power USB amp meter reads 5V , 0.11A

[mon2]

Any activity on the laptop when you short the gate to ground?

[waakye]

Nothing. Meter still reads 5V 0A. Press the power button , no leds. Do I need to assemble the laptop and test?

[mon2]

No because the current draw remains at 0A. Meter is ok?

[waakye]

Yes, the meter is ok. It measures the correct voltage and amperage on another machine.

[waakye]

Is this board beyond repair?

[waakye]

Can the bios chip be corrupted to cause this?

[mon2]

To me, the power delivery region is a suspect which is a stand alone circuit. If the pd controller and its firmware is working, then 20v should be selected. Suspect is the firmware for the pd controller. A pd bus analyzer can log the traffic between the logic board and the power adapter by monitoring the CCx pins. Will confirm later but affordable bus analyzers are available from ST, Infineon (Cypresses) and maybe Total Phase. There may be others but each should be under $100. AliExpress shows a few but not sure if they show the full traffic flow. I think they show the main components of the communication where the full bus traffic is desirable.

[waakye]

I will look for one on AliExpress. Thanks mon2.

[mon2]

This will work to confirm the traffic in spy mode:

https://www.st.com/en/solutions-refe...09404v1.html#1

Review the required cabling but with their free software, you can capture all the traffic.

[waakye]

Thanks mon2. I will have a look.
Is this the model STM32G071B-DISCO I should get?

[waakye]

mon2: is this the PD bus analyzer STM32G071B-DISCO that I should get?

[mon2]

Yes.

[waakye]

Thanks!

[waakye]

I will be receiving the PD analyzer tool today and I will test it out and report back. Thanks mon2!
hey mon2, if you ever in MTL. Beer is on me.

[waakye]

Hey mon2, I got the device and it's complex to understand how it works maybe you can help me out here.

[mon2]

This tool should allow you to ‘spy’ onto the power delivery lines to study the capabilities of the power adapter and respectively the selected best pd contract to power the board. If you see such traffic then the pd controller is working because it makes the request to the power adapter. Recommend to use tool on a known good pd adapter and target phone or MacBook, etc. The tool should log all traffic.

[anhbanxoi]

5V at the input also indicate that there is a short on power rail downstream. Try to measure diode mode on all coils, if there is no short then try to plug in the battery and measure voltage of PR304 to see if main power rail present.

[waakye]

Thank you anhbanxoi. I measure the resistance of all the coils to ground.
PL501= 31 Ohm
PL504 = OL
PL302= OL
PL301= OL
PL1110 = 3 Ohm
PL1105 = 1 Ohm
PL1103 = 1 Ohm
PL1102 = 1 Ohm
PL1100 = 8 Ohm
PL701 = 54 Ohm
PL601 = 238 Ohm

Thanks again for helping.

[anhbanxoi]

Thank you anhbanxoi. I measure the resistance of all the coils to ground.
PL501= 31 Ohm
PL504 = OL
PL302= OL
PL301= OL
PL1110 = 3 Ohm
PL1105 = 1 Ohm
PL1103 = 1 Ohm
PL1102 = 1 Ohm
PL1100 = 8 Ohm
PL701 = 54 Ohm
PL601 = 238 Ohm

Thanks again for helping.

PL501 is pretty low. Try to inject voltage 0.8V ~2A to this coil and see any components get hot or how much current it takes.

[waakye]

Hey mon2,
I attached the traces from each USBC port.
Thanks again