Audio Systems: car cd wiring, vauxhall astra, basic principle

Question
Halfords tried to fit a cd player in my vauxhall astra, the cd player worked when you turn the ignition key slowly but when the engine starts the cd player goes dead. They said it is to do with the ignition valve but the machanic said its wiring. I brought a vauxhall converter but still doesnt work? What should I do?

Answer
I need to know more about how it is wired in.

But, as a basic principle, the cd player must have constant voltage to keep it going.  If the voltage of the battery in the vehicle drops too low when the starter motor kicks in then the cd player will drop out.  BUT, it should come back on as soon as the motor starts up and the starter motor is disengaged and the alternator brings the voltage back to normal.

So, in your case, it would seem to me the cd player is connected to the wrong circuit.  It may be on just an accessory line that does not stay on when in the engine running mode.

GOOD NEWS: It is easy to find out what is going on.  Either you (if you have a voltmeter and know how to use it) or the installation tech merely puts a voltmeter on the 12v power line feeding the player to see if the voltage drops out when the ignition switch is in the ON setting.

Chances are, also, there are 2 12v power lines that must be connected - as there are in most cd players.  One of the lines comes directly from the battery through a fuse.  The other comes off the ignition or the head unit which turns on the cd player when the ignition turns it on. This one is often called the remote turn on line.

So, check it out and let me know if you need further thoughts.

C