135 Watt Silverface Twin Reverb Fuse, 4 or 5 Amp?

[Injam]

Hello,
I got a 1977 Fender Twin Reverb recently. On the back panel where the fuse is located it states: 4 amp slo-blo. When I looked at the fuse that was installed it was a 5 amp. Next I downloaded the wiring diagram to verify the back panel. But the wiring diagram says to use a 5 amp slo-blo fuse. Do I have a super rare vintage amplifier with a mistake on the back panel?

 

[Phrygian77]

4A 250V time delay (slow blow) is more than sufficient.

 

[Milspec]

4 amp

 

[dsutton24]

Unless I've completely lost my faculties altogether, it looks to me like the schematic you posted says 4 amps. That's where I would start anyway.

 

[Powdog]

For 1977-82 135 waters.

 

[Jon Snell]

The back panel is what you go by.
5A is required for 100volt power supplies; Japan etc.
4A is required for 120v USA and 3A is required for 230v Europe and 240v UK/Australia.
All Time Delay type fuses and preferably sand filled HRC type.

 

[rdjones]

I have a Bassman 135.
For the most part it is the same circuit minus the reverb and tremolo.
The schematic shows "4 AMP" and the panel calls for 4 Amp.
It has a 4A fuse installed.

The schematic you posted calls for a 4A fuse in the US 120V version.

Are you blowing fuses ?
If not, I'd install the correct 4A fuse.

 

[rdjones]

View attachment 997155
For 1977-82 135 waters.

His amp is the US version, as noted by the presence of the convenience outlet.

 

[Injam]

Unless I've completely lost my faculties altogether, it looks to me like the schematic you posted says 4 amps. That's where I would start anyway.

You are correct. I was confusing the symbols for the plug. Thanks

 

[Milspec]

If you are blowing fuses, suspect rectifier diode failures. For some reason every SF Twin I have seem to have cheap diodes installed that needed replacement.