Bronco amp - first glimpse

[Yorkie]

Hi David,
I take on board what you are saying and agree with you.
I'm also a bit concerned that this amp has no earth connection too (as I am aware that many early amps didn't).

Thanks

Rob

As far as the amp itself is concerned Rob, the only mains connections are to the primary of the mains transformer via the on/off switch, and the fuse-holder. Everything else is powered from the mains transformer secondary, and thus, is isolated from the mains. I do though notice that there's a .047 cap from the mains input to chassis, so that certainly needs to be a class X or to be snipped out as it's not strictly necessary. (If the existing cap was to go short circuit (as one has just done on me in a sewing machine motor speed control!) it would put mains onto the chassis, but then the 1A fuse would instantly blow).

I assume that your main concern as to earthing will be the safety of any equipment that's attached to the input such as a guitar, and whether or not the metalwork on the guitar could become live. If you wish to (given that it has a mains transformer - not a live chassis), there's no reason why you can't fit a three core flex with the earth lead to the chassis for your reassurance.

I'm not sure what type of mains switch the amp has, but some of those featured on the website have flimsy single pole slide switches. You could fit a more substantial double pole toggle switch such as this one:

http://www.maplin.co.uk/dpdt-toggle-switch-2355

Of course if that would alter the front panel layout, you'll be very reluctant to do that.

Apart from the fact that this equipment dates back to a less safety conscious era, as with Heathkit it was initially designed for the American market on 110V mains, so they took a more casual approach to not bothering to earth equipment, even if housed it metal cabinets (which your amp isn't of course). I've got a Heathkit RF1U signal generator (metal cased) which originally wasn't earthed but I've fitted a three core flex to it. (the 'U' suffix was applied to Heathkit equipment marketed in the UK).