Help with dimmer wire in '04 please!!

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Nov 21, 2010 | 12:41 PM

MR.DYNAMITE

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From: Casselberry FL

Help with dimmer wire in '04 please!! Illuminated Humount

Hi guys, here's what I have going on: 2004, just added an Alpine CDA-117, Roem VET and a Humount illuminated surround. After some dicking around I got all that working. But in the current wiring set-up, the Humount comes on WHEN THE KEY IS REMOVED, AND NOT WHEN EVERYTHING ELSE IS ON. I tapped into the HVAC harness cream wire, just double checked via pics on this forum and it seems to be correct.

So to be clear, I ran a wire from the HVAC cream to the orange illum wire on the head unit, the hot of the humount illumination is tapped in there as well. The Alpine lights up properly, not too sure the lights on it dim with the rest of the dash.

Any help is appreciated, I want to put my console back together!

Ethan

Last edited by MR.DYNAMITE; Nov 21, 2010 at 05:09 PM.

Nov 21, 2010 | 01:16 PM

heavymetals

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From: Torrance Calif

I had to add a transistor and a couple of resistors on my AVIC as the dimmer control is reversed as to what the unit wanted to see.

http://www.play-hookey.com/digital/e..._inverter.html

Some units you can reverse the logic in setup.

Sounds like you Humount is the same.

Nov 21, 2010 | 01:32 PM

MR.DYNAMITE

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From: Casselberry FL

Hmmm. Thanks! I'm much better at that kind of stuff than car audio. Seems elaborate for a 2 wire bank of LED's but is probably what is required.

Nov 21, 2010 | 01:38 PM

heavymetals

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From: Torrance Calif

I figured it out by hanging a scope on the dimmer line and watching what happened.

The dim function is controlled by pulse width (duty cycle).

Nov 21, 2010 | 02:13 PM

MR.DYNAMITE

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From: Casselberry FL

Wonder if I could hook it up to switched acces. power with a pot, set and forget. Not sure I need the dimmer functions, it just has to glow, you know? Do you recall what voltage the dimmer line is?

Nov 21, 2010 | 02:21 PM

heavymetals

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From: Torrance Calif

Dimmer line is not a voltage control.

It is a square wave that is stretched or compressed depending on brightness.

That is Pulse Width Modulation.

The pulse is probably inverted as to what your device wants to "see" to operate correctly.

The transistor and three resistors will cost you less then a buck.

Nov 21, 2010 | 04:10 PM

markcz

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From: North Augusta, SC

The illuminated HUmount I had a few years ago simply needed +12vdc to turn on. Connect it to the switched wire you have turning on the HU itself, or use the remote amp wire coming out of the HU if you want the surround blacked out with the radio off. Either way it will turn off when the car isn't running.

Nov 21, 2010 | 05:09 PM

MR.DYNAMITE

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From: Casselberry FL

This post will probably be useful for others. I unded up using 12v. switched power and a 5k ohm potentiomenter (as suggested from Humount), works perfectly so far and has it's own brightness control. The dimmer wire method, as taken from Humount's instructions, doesn't freakin' work. Thanks to the forum members for their help! Heavymetals told me what the problem was, enabling me to get it going today.