"A "T 6.3" amp fuse is too big for a tube scope - "

Says it right on there if you look at the picture. IIRC the rule is to go by the marking on the unit if it differs from the manual.

I don't see a 6.25 amp as too big for that thing, I believe that is a body builder model with two handles and probably as many tubes as a 1950s color TV set. They pulled over 300 watts, alot of them almost 400.

I believe that scope is more than 50 tears old, I would say circa 1957. Even without transistors they did get a bit more efficient over the years. My old 561A doesn't pull as much as that dinosaur, and I think the only solid state in the is the rectifiers. not sure. but after some years tubes (valves) wound up with more gain so less of them were needed.

The OP should just put a damn seven amp fuse in it and try it. It does not have a fissionable material in it nor any explosives. If you are paranoid keep it away from the drapes, or hell just do it outside. Respect electriciy yes, but put it in perspective.

If it blows the fuse immediately the first thing is to disconnect all the rectifiers off the secondaries of the transformer to see if that's good. In fact if it powers up and has no trace it could still be the transformer. My 561A has leakage to the filament winding which shorts out the HV. I took a hi-pot little 6.3 volt transformer and wired it in, it works fine. However once insulation is breached.......... The nice thing now though is that the HV is no longer applied to that winding.

I remember that Tekronix had a lifetime warranty on their power transformers. I tried to get a replacement for mine and they would sell it to me but that is all. It's not like they didn''t have them. They basically said that they are no longer under the lifetime warranty. The rep also mention that they had alreacy been to court about it, it was like $150 or go **** off.

Maybe I should look at a Gould next.