1702(T) monitor with unknown schematic

Hi all,
I've been given a 1702 (with a Toshiba CRT) monitor to be fixed.
Symptom is no video, no sound, but CRT anode voltage is present and
horizontal scanning is present (no vertical scanning is present on the
vertical deflection coil, though).
I've downloaded a service manual (it says preliminary) from
zimmers.net but I've found the schematic to be quite different.
In particular, I've found an open fuse (F501, T630mA marked on the
PCB) on the main PCB but this isn't shown in any schematic on the
service manual, nor is present in the parts list. Interestingly, the
fuse is in parallel with a diode which tests good at DC and it's not
anywhere in the schematic too. The fuse is placed between two pins of
the flyback transformer.
Now, I'll try replacing this fuse, but I suspect it didn't die of old age.
Is there any hope to find the correct schematic for this monitor? PCB
has the following codes: CK10307-001(1/8) GCMK-81X, but google doesn't
seem to believe it's a Commodore monitor if I try to ask.
Any hint?

Thanks,
Frank IZ8DWF