Arduino Uno with CNC shield not connecting

Hello, I'm currently building an Arduino CNC Plotter. For this I'm using steppers from old DVD drives, to controll them I use the Arduino CNC shield paired with an Arduino UNO. It already worked connecting them to my PC and controlling the stepper, but since a few days the Arduino is not recognised by the PC anymore when connected to the CNC shield. I already tried out different power supplies, but it still won't work. Anybody with an Idea for that? Thanks in advance

That calls for schematics showing the troubeling setup.
Links to the shield and power supplies, please.

Sorry for forgetting that.

The power supply with which it had worked is just an adjustable supplie which I found at home. It has 600 mA and can be adjusted between 3 and 12 V. It worked with 12 V.

Thats the shield.

Problem is solved one of the drivers is faulty. It works if it is removed. Thank you

Welcome! Please mark it closed.