Just purchased a "marine" JBL am/fm/cd-player with lousy instructions.
The unit must be an auto radio since there were 12 wire wiring
harnesses and instructions appropriate for auto installation. I have
finally figured out which wires were appropriate to use (there were two
blacks and two reds in two different wring plugs). However, when the
radio is powered, the faceplate lights up but no numbers, stations,
band info, etc. appear or does the unit do anything else but light up.

Have I done anything wrong here? Also there is a yellow "+" wire that
is said to go to the ignition and it seems to help the unit retain its
memory. Will the unit run without this being powered?

Thanks for your help.

Stan