I can remember when Kustom first came out. I saw Buddy Rich’s bass player with one. That would have been mid-seventies, but they had been around since the early sixties. They were unusual (they looked like something out of a spaceship) and doubly so, because they were all solid state. Very few transistor amps were around at that time, nearly everything was valves, and for good reason. The transistors of the time were very dubious beasts, and we (the folks who had to fix ‘em) knew not very much about them. Whereas valve technology had been evolving for probably fifty years.
The OC and AC range of transistors were about all you could get, and they didn’t like high voltages, high currents, or heat, very much. I never did find out what they did like.
But to get back to the plot. Whatever it was.
The gentleman who owned this last one I saw (I’ve seen a few in the last year or two), had revalved it, and I think had a replacement mains transformer fitted. All because it didn’t work. The actual fault was a 5 watt dropper resistor (3.9k) that had gone open circuit. A couple of quid or so, as opposed to £100-ish for a revalve and 50+ for a transformer. And all the labour.
If you are handy in amps (you can always tell a reasonably proficient electronics feller; he has two working arms and hair that isn’t black and smoking) the easiest way to check the state of dropper resistors, is to switch on the standby and put a meter on pins one and six (the anodes) of any ECC 83 you might find.
All this is all far easier if you have a drawing. A schematic is essential if you are concerned about wasting time and money.
Un….fortunately, schematics for the ’36 Coupe are kept in a cupboard guarded by Tyrannosaurus Rex, somewhere on Mars. This is how to keep your customers happy? I don’t think so.
Tea and macaroons are now necessary. Just after I’ve jumped up and down on a picture of the MD of Kustom Amps.