Audio Systems: power to head unit/cd player, audio business, baily

Question
hi. about a week ago i installed my jvc touch-screen cd player in my dad's car by myself. it looks like a normal cd player. no dvd or big screen or anything. it seemed to work fine as i played it for about 5 minutes. i turn off the cd player so i could wrap black tape around all the wires. and then i try to play it again and it all of a sudden doesn't work. i connected and disconnected the wires several times, for about 4 hours. and there still seemed to be no power going through. but i tested out the cd player with a power supply/battery and it still worked fine. so i checked all the fuses and they were fine also. i brang the car to a friend who used to work i the car audio business and he couldn't find out what was wrong either. so can you tell me what you think is the problem? thank you.

Answer
Hi Dennis,

Good to hear that the deck is ok. Here is what i would do... Get a multimeter place the (-) lead to a known good ground point (frame of car somewhere) Check for voltage whilst ignition is totally off. there should be +12V on 1 wire. Turn ignition to ON, now an extra wire will also have +12V. IF both of these wires have 12V available, Check GROUND connection - check with Ohms/continuity range.

If all these check out... Hook the deck up and retest as under load things can quite dramatically change.

Regards Baily :)