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View Full Version : Car charger + AUX input = ground loop whine



MJC
10-06-2010, 11:52 AM
Wanting to use my DX for music and NAV in my car but I am getting a nasty ground loop whine when I connect the charger to the phone. I am using the VZW MICRDUALVPC universal charger and using the overhead AUX input that I have used for game consoles and my SE phone without issue. This is in a Ford Explorer with the "audiophile" sound system and the rear entertainment DVD system so that is the only AUX input I have and there is no direct BT attachment available without ditching the DVD package and I'm not looking to spend big $$ to replace the whole thing just to add the phone.
Does anyone know of either a car charger with a filter (or just a better ground) or possibly a small BT reciever with line out I can mount in the car? Any car audio guru's familiar enough with this system to know where I need to add a ground/filter?

Thanks.

CBGOODMAN200A
10-06-2010, 12:15 PM
Are you sure its not a problem with something on the truck? I have been using the same set-up with no issue. I hope you can resolve it, because it makes an excellent travel companion. In fact I cut off the navigation service on my OnStar.

tracey
10-06-2010, 12:20 PM
I had the same issue except instead of a whine it was that my left speakers would only play static. It turned out I had a short somewhere in the electrical system. I can't tell you where since I didn't fix it, but the person who did found it for me when installing my new bestbuy head unit.

Someone on here suggested I test it with my car off and only on accessories. That was how I ruled out an engine problem because it still had the problem when my car was off.

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BuRNiN_BoNeS
10-06-2010, 12:40 PM
If you are getting the alternator whine, it should disappear while engine of key on? Correct? If so you need to put a diode on your ground cable large enough to support your amperage needs with the anode facing towards the body ground... I believe that should cure your problem if it simply is a ground loop...

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MJC
10-06-2010, 01:00 PM
It is alternator whine, no issue with the engine NOT running and the pitch changes with RPM. Other devices I've used probably have a little better filtering (or at least some filter) in the charge adapter. I know the bigger issue is the way the whole system is designed but it's factory and otherwise I'm happy with it for this vehicle.
@BuRNiN_BoNeS: Thanks for that diode tip, I feel a bit foolish for not thinking of trying that right away. I've built more than a few large audio systems but last one was 10 years ago. I remember building something way back when with 2 diodes (push/pull) and a capacitor and instilling it behind the lighter plug. Hopefully a single diode will work for this.

Arak-Nafein
10-06-2010, 01:57 PM
I had this same problem when I forgot to ground the radio head unit that I installed.

tmar23
10-13-2010, 09:05 PM
I had the same problem, drove me crazy. I solved it by using my standard house charger plugged into an dc/ac adapter which I had from previous phone (so I don't have to buy a car charger for every new phone I get...). Works great, and no more whine/noise.

BuRNiN_BoNeS
10-13-2010, 09:08 PM
I had the same problem, drove me crazy. I solved it by using my standard house charger plugged into an dc/ac adapter which I had from previous phone (so I don't have to buy a car charger for every new phone I get...). Works great, and no more whine/noise.

I'm actually surprised this works for you, generally this makes the whine worse

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jefflikesbagels
10-15-2010, 12:42 PM
I have the same whining with RPM problem in my 05 Honda Accord. I was thinking about getting dc/ac adapter so i could try it out that way, but i wasnt sure if it would actually fix the whine.

It gets so bad that i have to unplug the charger whenever i want to listen to music.

BigDaddyNYY
10-15-2010, 01:03 PM
I picked up a ground loop isolator from Amazon for $8 about 2 years ago when I had the same issue with my XM receiver, so if you don't want to build something, you should be able to buy one rather cheap.