Cool will report back. Do you know by any chance what Fuse f1 does?
F1 is the input fuse for the high voltage section for the displays.
before you replace the fuse unplug J2 and see if the fuse blows again.
if it does then the problem is in the HV section.
As long as F2 and F3 (+100v and -100v outputs) are the correct value if F1 blows then the fault will be a faulty component or components in the HV section
If you intend to use led displays then just leave the fuse out as the high voltage section is not needed for LED score displays
