No usb connection on 12V input at MKS Board

Hey there,

i have a strange problem with my MKS board lately.

my hardware:
MKS Base 1.3 with Marlin
12V Power Supply

my problem:

i can connect to my mks board when usb only is plugged in, as soon as i plug in my power supply i lose my usb connection to the board.
also i printed with my laptop+cura at the beginning. one day the print just stopped every time shortly after the start, so i switched to sd card printing.


i already checked if the 5V is clean and if the two GND of 12V and 5V are connected. both is fine

iam out of ideas and i cant find a schematic for the board

anyone got an idea?

... can you measure potential differences between the GND's of your PS and the USB-port? - some of the chinese PS'es have weird internal potentials, so there can be high currents running across the USB shield, what's causing many problems up to burning the PC's USB drivers

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Wow nice guess
There is no potential difference but when i change the chinese ps with my labor supply it does work

Thanks for the help!