question about line voltage wiring to on off switch and fuse

[mikepukmel]

Ive looked at images from a bunch of Fender and Fender clone amps. It looks like on the real Fender amps, one leg of the line voltage wiring goes first through the fuse, then from the fuse to the on/off switch, then to the PT.

A few either reworked or clone amps, with new 3 prong wiring, have the black hot leg of the line cord go first to the on/off switch, then to the fuse, then to the PT, and the white leg goes right to the PT.

It sounds like, for safety, the fuse should be dead if the on off switch is in the 'off' position? So, the black line lead should first go to the on/off, then through the fuse, then to the pt?

Thanks,
Mike

[Enzo]

In th old days Fender wired the mains to the fuse and the switch for convenience. But in reality we should wire the hot to the fuse and the switch and the neutral to the transformer wire.

[mikepukmel]

In th old days Fender wired the mains to the fuse and the switch for convenience. But in reality we should wire the hot to the fuse and the switch and the neutral to the transformer wire.

Thanks Enzo! And, should I put the hot lead to the switch first, then from the switch to the fuse? I.e., so turning off the switch, the fuse socket is dead?

[Enzo]

Me, I do it the other way, fuse first. I want the fuse fusing the whole thing, not the whole thing except the switch. A rare but possible (as in I saw it once)short from internal switch contact to frame needs protection.

If I want the fuse socket dead, I unplug the unit.

[Justin Thomas]

I thought the Hot (Black) should go to the center terminal of the fuse holder, then from the side terminal of the fuse holder to the power switch, then to one leg of the tranny? The white wire should go straight to the tranny, and the green should go straight to the chassis... in the case of a gross fault, you want the fuse to be the first thing to go.

In the case of a 2-wire amp, it would seem safest to use a double-pole switch. Getting the fuse in Hot or Neutral seems like it'd be a crapshoot, depending on which way the plug was inserted. Because I have yet to see an amp with a polarized two-prong plug...

In any case, I didn't think we should be still building amps with 2-wire cords, anyway... And even if you're repairing a vintage piece, they should have a 3-wore installed unless they're sitting in a museum?

And all of the above takes for granted that the socket you're plugging into is wired correctly to begin with...

Justin