Sorry Duimon, GT65 had a DC jack but it was possibly for some kind of plug-in, it works without plugging it in as you can see in this video:
https://www.youtube.com/watch?v=Q9IR2QZP1sI
If you plan to improve the Amstrad monitor screen, more rounded screen corners would be great
Thank you very much for your art and for making happy to some nostalgics