How many volts should the constant and ignition be sending to the head unit?

I checked mine with a DMM and got 14 for constant and 4.5 for ignition. Reason I ask is my head unit is not working and Im trying to track down the problem, seeing as it didnt occur until i pulled the head unit out to put a DIN cage in, thanks

 

Should be 12~14 volts depending on whether the car is running or not. Check the fuses under the dash and the fuses under the hood. Should be a 7.5A fuse.