I installed a new Alpine head unit. All the connections are correct so that the head unit is only powered when the ignition is on, but when I go from the "Engine On" key position to the "Accesory" key position (one click back), the power to the head unit blinks causing the CD in the head unit to pause for about 3 seconds before continuing... a bit annoying. This didn't happen with the stock head unit.

Can I install a capacitor of some sort here to keep the voltage to the head unit up during the split second when I turn the key from "Engine On" to one click back?

 

a lot of alpines need the yellow constant connected direct to the battery due to its higher draw of power. did you do that?

 

[QUOTE]Originally posted by lucid
[B]a lot of alpines need the yellow constant connected direct to the battery due to its higher draw of power.

 

There are two power wires going to the head unit. One is a constant +12v that is used by the head unit for its memory and clock display (if it has one). The other is +12v accessory, switched by the ignition. This is what the unit uses to spin your CDs, output sound, etc. Unfortunately power to this circuit is interrupted when the car is started, and sometimes when the key is switched to accessory from run, as you noticed.

The solution is to wire it so that both power wires to the head unit are constant +12v. This way, your head unit will think it is always on. It is then up to you to turn it off when you exit the car, since you are taking the ignition out of the decision-making process.

 

To keep the +12V power from the ignition lead from dropping for a split second, can't I just use an inline capacitor or something?

[QUOTE]Originally posted by jzr
[B]...The solution is to wire it so that both power wires to the head unit are constant +12v.

 

No, an inline capacitor will block all dc power, you could use one in parallel just make sure that it is large enough to deliver the required current load.

 

Okay, so I need to wire a capacitor parallel to the +12v ignition wire. Do I need a resistor in series with the capacitor like this picture indicates?



Also, what rating capacitor should I need? I took an electronics class a few years ago, but it never was my specialty.

 

You won't need the resistor. Size will depend on how much power it needs to supply for the short term.