Hi Jimmy.
Thanks for the instructions for the charger. I am trying to connect mine to my Graupner Polaron, but I am confused.
I think the colours are different on my flat white connector. I have (left to right) red yellow blue white black.
I think m ground lead is black. It used to be 50 years ago.
I've done it the same as in your photo, but my blue wire goes to ground. (end terminal) My blue wire is in the middle of the five wires at the white plug.
Is the black lead the ground wire ? Are my colours different to yours. ?
Find the gnd wire coming off the balance lead, solder that to the main power gnd, and then the rest in order as shown in Jimmy's picture.