Hello Erik,
Thank you for writing in.
Is the output voltage of the product is 24V when without connecting the printer?
Have you checked that if there is reverse connected of the positive and negative sides?
It is better that you can send us some images of your wiring to let us check the problem details.
You can send the images and the information by email (service at droking dot com)
With your help, we can find a solution more quickly.
Looking forward to hearing from you.
Best regards