820-00928 With a power cycle issue


I have an 820-00928 that when plugged in jumps from 5v to 20v and pulls up to 1.8a but then reboots the charger back to 0.2a. The screen shows the battery and then goes off again when the charger drops back to 0.2a

Does this on all 4 ports.

I've checked U3100, U3200, UB300, UB400 and the main issue I can see is the following:

UB400 USBC_TB_CC1 I only get 0.080v
UB300 USBC_TA_CC2 I only get 0.132v
U3100 USBC_XA_CC2 I only get 0.004v

All others test as about 0.520v in diode mode.

So do you think there's a chance UB400, UB300 and U3100 need replacing or am I not looking far enough into this?


Staff member
CC1/2 lines get different voltage, depending on the connection sense.
Keep in mind, USB-C port has 2 connection ways possible; the detection is done with CC1/2 lines.

Is the battery charging?
If not, get a charged battery and test machine again.
Be sure to use 87W charger.


Yeah works on 2 ports with an 87w charger. Hadn't noticed the one I was testing with was a 61w version.

On one of the ports its fine with the USBC plug turned upside down but not the other orientation.
On another port, I get 5v only with the plug one way round and 0v the other way.

I've tried 3 IO boards and all three do the same thing.

At least its powering on with two ports though