Boomlander wrote: ↑Sat May 29, 2021 10:59 pm
The unit has three wires running from the rear of the unit.
The red one with inline fuse is obviously the live feed, there is also a black wire and a brown wire.
Would I be correct in assuming that the black would be the earth lead and the brown would be the live connection to the single speaker?
The speaker itself has two spade terminals one with a red mark on it which I assume is the positive and the other I guess would be wired to earth?
Possibly...but very unlikely.
it's almost certain (and I only caveat that because it's such a long time ago) that the the Black/Brown are the 2 wires for the speaker and the Earth Return path for the radio power is simply via a good body strap connection, or there may be a earth lug/terminal on the exterior of the case.
I don't believe speakers have ever used the bodywork as the return path for the speaker signal.
Mixing the tiny voltages involved with the speakers with all that 12v power generation just doesn't sit comfortably with me.
But if there is a Radio Expert out there to say otherwise.... I'm happy to be corrected.
You've not said how 'Vintage' it is, but in my experience, the earth for the power was always via the body up until sometime in the 70s, or possibly even 80s.