Luckily I've found a full monitor which works fine on 12VDC [one from the TV scrap container at the council dump

Also the Lenovo Idea Centre Q180 computer that we both have does indeed work on 12VDC rather than the prescribed 19V . I just had to try the 12 - 19 VDC converter first which blew fuses and made smoke

cheers
David M0YDH