Peavey Ultra 60 Head - Underrated 1A FB HV (F2) Fuse?

[misterc57]

I have this Ultra 60 with a blown F2 fuse, it was a 1A fuse and it feeds the HV. The board and schematic states 1A FB.

After replacing with a 1A FB I found nothing else wrong. I am wondering if the fuse should be 2A here, which is what is used in the Ultra Plus 60 amp?

Perhaps 1A is underrated and blew? There is 473 V on the plates.

Thank you, MC

Peavey-Ultra-60-Schematic.pdf

[Jon Snell]

I would have thought a Time Delay fuse would be more appropriate than a Fast Blow. A 2A is not a good idea!
150u of capacitance to charge up very quickly at switch on ... or does it blow when in use?

[misterc57]

It came to me with the blown fuse.

It does not blow with the new 1A FB I placed in there. I have had several on/off cycles and have played the amp.

[misterc57]

If you turn the amp ON and the STANDBY is in the OPERATE position, there is a large spike that exceeds 1A.

[Greg Robinson]

Cartridge fuses DO wear out - every power on they're subject to inrush current and magnetostriction that will eventually cause the element to fatigue.
Or, it could have blown due to some other transient cause - power tubes often have intermittent shorts that may only occur once the structures have warmed up and sagged, or are vibrated in a particular way.

F1A is already very generous. A 2A fuse would be a very bad idea.

[Jon Snell]

Without history on this amplifier, it could be a tired fuse.
If you fit a fuse of th wrong rating and type and the amplifier causes injury or damage, you will be held liable for any damages.
Fit an F1A 250v Glass fuse from a known seller to be able to sleep at night in the knowledge you did nothing wrong.
Eventhough a T type fuse would be more appropriate in this situation.

[misterc57]

Good info. 1A FB it is.

Thank you everyone.

MC