I do not know: it is a HP laser printer and they, apparently had all kind of problems installing it in the first place.
But it is definitely not new, as a son of the owner has returned home (temporarily) pending a divorce etc. and brought this printer with him.
Anyway, I will get the system next week and check for myself; see what can be done. And, I guess, the printer will be there for a limited period of time anyway.
My mistake was that I did not link the printer driver with power management.
Thanks again for your support.