Hammond 43-1 Amplifier - Fuse Size?

[smilan]

Hi
I'm converting this organ amp into a guitar amp.
Right now there's no fuses in the PSU.
The schematic refers to 5 fuses between each one of the secondary taps to the rest of the circuit, but I don't think there's enough room for adding 5 fuses in the chassis.
So instead I would like to add one fuse between the on / off switch to the primary side of the power transformer.
How can I calculate the fuse size?
Attached link to the schematic:
https://i.ibb.co/dDdxtn8/43-1-schematic.jpg

 

[volker]

A primary fuse can't take the place of secondary fuses, you actually need both. That said, F1/F2/F5 are a bit overkill, there really is no need to fuse AC heaters. A 1A slow-blow should be right for the primary.

 

[smilan]

Thank you!