Question about Alpine CDA-7840

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Alpine CDA-7840 Just installed in a 92 4Runner, Rear channel speakers do not work with the CD. Have check the balance and the fad. Everythings is fine with just the radio.

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Re: Alpine CDA-7840

Some 4-Runners have a factory system that uses a separate amplifier to power the rear speakers. In this case you need to activate the amplifier using the blue/white remote output from your Alpine deck. It sounds like the wire that activates the amplifier is currently attached to the deck's blue "power antenna" output, so that the amplifier is only on when the tuner is selected. Disconnect whatever is attached to the blue wire behind the deck, and attach it to the blue/white wire instead. That should solve the problem.

Posted on Jun 09, 2007

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Are you running your rear speaker through an amplifier? If so, you are probably using the blue wire (power antenna remote turn on) instead of the blue/white wire (amp remote turn on). The blue wire turns off when leaving tuner mode, thus turning off the amplifier.

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I have the alpine cda-7894 in my 1994 mustang. I have the mach speaker upgrade. When I play my music the sound has no depth and sounds very flat with no bass, but if i change the balance to the right or...

You have a problem with the phasing of your speakers. This will happen if on or more of the speakers are installed incorrectly. To solve this, you must check the speakers and find which one of them does not have the positive and negative connected to where it should be. When connecting speakers it is crucial that the speakers (positive and negative terminals) are all connected to the corresponding (positive and negative) speaker outputs of your head unit. Now you can enjoy your sound again.

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How to ajust speaker front to back

Hello bill_cordova,

Start with the "AUDIO" button. Press it until FAD appears in the display. Press the up/down buttons to adjust front/rear balance. FAD:F15-FAD:R15 is displayed as the front/rear balance is moved from front to rear. FAD:0 is the center position with the balance equal between the front/rear speakers.

Hope this helps. If it does, please rate as "FixYa".

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check out
this site has your stereo's wire diagram.

The amp wires only go to the rear output (rca jacks on back of cd player)
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Jan 16, 2009 | Alpine CDA-9856 CD Player

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What kind of car did you install this in? Did it have a factory radio in it? If I had to take a guess I would think that there is a factory amp that you may have hooked the blue wire from the alpine deck to. If this is the case when you switch to CD the alpine deck turns off the power to the power antenna lead(blue wire) and thus your factory amp. If this is the case hook the factory amp turn on to the blue and white wire and you should be good to go.

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Certainly, the output IC might need to be replaced, also check to see if there is a factory amp somewhere in the car. Additionally, double-checking the wiring is a must. How long does it take for the unit to heat up?

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