electrical problem

i just installed a new radio in my 84 300d. i used the 3 of the 4 wires from the old radio. the red one is always hot the black one which is hot only when the ignition is on and the grey one is ground, there was a brown wire to light up the radio lights but i just left that one empty(insulated). i think all my wiring is OK but the #2 fuse that controls the buzzer and all the panel and switch lights keeps blowing out, incidentally that brown wire i mentioned above is controled by that fuse as well. i rechecked all my wiring but all is in order. can any one help me.
thanks