The Radio Information Board

Will this repeater operate without the HM-4 microphone connected?
Purchased this radio used, and all that it does is light the power lamp green. All other led's do not light. Cooling fan does not run.
It looks like I might have got hosed on this set.
TIA,
Lou

Found out that the mic does not have to be connected. This repeater has a burned rectifier diode, thats why no front led's. I powered it up with a 12 volt battery, and now the transmitter continually operates.
Another Ebay hoseing