I have the 12v battery (it is actually 10 Ni-Cads in series), and, of course, it has a red wire coming from "+" and a black wire coming from "-".
However, on the schematic I am confused about whether the red wire should go to terminal 24, or the black wire. (It's the top line, with terminals 24 and 20.)
I was changing the batteries and didn't take a photo of the connections first, and didn't see this battery was -12v, not +12v. Stupid...
Appreciate any help. This is probably very simple for anyone here, but I don't want to make mistake and bolax this instrument.