The red wires at pins 3/4/c/d should be +5 volts DC.
The wires at pins 5/e should be -5 vdc (if they are present).
the wires at pins 6/f should be +12vdc.
Pin 1/2/a/b are ground, so your black lead goes here and your red lead goes on the others.
Of course, the real voltage readings should be done at the chips on the boards....