How to disable PDF input?

[Michele Alessandrini]

Hi, excuse me all, it's a long time I cannot print anymore, our network printer crashes and reboots every time I send something.
I have Debian Testing, and I discovered the problem is that recently programs have switched to use PDF instead of PS as job format. In LibreOffice, where there is an option to choose the job language, it works if I set PS, but all other programs have no such option. I suspect the problem is in PDF->PS conversion. I hope such a conversion happens, because the printer's PPD does not say it supports PDF!
I searched a lot but I cannot find what I'd like to try: disable PDF input in cups, so forcing (hopefully) programs to output PS again. Is it possible?
I tried raising the "cost" of pdftops in mime.convs, or commenting the whole line, but programs don't care and keep outputting PDF.
Thank you very much.
Michele Alessandrini