ground loop

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hamzter

Copper - Posts: 116

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Joined: March 15, 2005

Location: United States

Posted: June 09, 2007 at 8:46 AM / IP Logged

So I was wondering if there is already engine whine in the audio system, how does adding more grounds to the head unit help?

Mark "Hamzter" Cinense

1991 Infiniti G20 w/JDM SR20DE

Eclipse CD8445

MTX Thunder 684

Polk DB6750

Polk DB6500

Optima Red Top in the Trunk

DYohn

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Joined: April 22, 2003

Location: Arizona, United States

Posted: June 09, 2007 at 9:27 AM / IP Logged

It doesn't necessarily. What helps is getting all system grounds at the same potential. It's not about "adding" it's about "improving."

Some head units introduce ground loops no matter what you do and must simply be replaced.

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hamzter

Copper - Posts: 116

Joined: March 15, 2005

Location: United States

Posted: June 09, 2007 at 9:42 AM / IP Logged

I am having a hard time believing that a quality Eclipse HU (CD-8445) would introduce noise into the system.

The original ground was connected to the chassis = noise. Then I moved it to the harness = noise is significantly less, but nonetheless still present and still in conjunction with acceleration.

When I installed my new alternator, since it needed replacing, I did the BIG 3 upgrade since I was there.

Engine noise still present...

Mark "Hamzter" Cinense

1991 Infiniti G20 w/JDM SR20DE

Eclipse CD8445

MTX Thunder 684

Polk DB6750

Polk DB6500

Optima Red Top in the Trunk

DYohn

Moderator - Posts: 10,741

Joined: April 22, 2003

Location: Arizona, United States

Posted: June 09, 2007 at 11:37 AM / IP Logged

You say you installed a new alternator. Try improving the connection between the alternator's case and the chassis. And yes, even an Eclipse can be defective.

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hamzter

Copper - Posts: 116

Joined: March 15, 2005

Location: United States

Posted: June 09, 2007 at 12:01 PM / IP Logged

DYohn wrote:

You say you installed a new alternator. Try improving the connection between the alternator's case and the chassis. And yes, even an Eclipse can be defective.

I installed and additional ground on top of the original ground. Would this cause a G-loop?

Mark "Hamzter" Cinense

1991 Infiniti G20 w/JDM SR20DE

Eclipse CD8445

MTX Thunder 684

Polk DB6750

Polk DB6500

Optima Red Top in the Trunk

DYohn

Moderator - Posts: 10,741

Joined: April 22, 2003

Location: Arizona, United States

Posted: June 09, 2007 at 12:18 PM / IP Logged

Did you try connecting the ground directly to the alternator housing?

Have you measured the resistance between your ground points with an ohmmeter?

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hamzter

Copper - Posts: 116

Joined: March 15, 2005

Location: United States

Posted: June 09, 2007 at 12:30 PM / IP Logged

DYohn wrote:

Did you try connecting the ground directly to the alternator housing?

Have you measured the resistance between your ground points with an ohmmeter?

yes

here is what I have as follows:

Battery - to chassis = .010

Grounds to Amp - = .003

Alternator - to chassis - .001

chassis to engine = .000

with this said, I think the head unit might be toast. reason I say this is that when I turn the volume from 01 to 00 I hear a little faint pop sound. This is with my amp gains turned 3/4 or all the way down to 0.

What do you all think?

Mark "Hamzter" Cinense

1991 Infiniti G20 w/JDM SR20DE

Eclipse CD8445

MTX Thunder 684

Polk DB6750

Polk DB6500

Optima Red Top in the Trunk

DYohn

Moderator - Posts: 10,741

Joined: April 22, 2003

Location: Arizona, United States

Posted: June 09, 2007 at 12:39 PM / IP Logged

Yes, those are good ground return readings. You should have no ground loop issues with those numbers. If you have noise in your system there are still several things you can check, but unfortunately the most likely is the head unit.

-edit- did you measure resistance between your HU ground and the alternator ground?

Other things you can check: integrity of RCA cables; speaker wire grounding out or bad speaker (only an issue if the noise is in one speaker but not others); routing of RCA cables in relation to any high-energy systems in the vehicle; ignition system noise. Ignition system (or engine ECU) noise is by far the hardest to find and the hardest to fix. If you change your HU and your RCA cables have been eliminated as a cause, it might be an issue with the vehicle.

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hamzter

Copper - Posts: 116

Joined: March 15, 2005

Location: United States

Posted: June 09, 2007 at 12:45 PM / IP Logged

I am now looking for a new Headunit... ground loop -- posted image.

The only thing I am thinking about is whether I should with another Eclipse or Kenwood Headunit. I have Kenwood in the Subaru.

The Eclipse is in the Infiniti G20 1991...

Mark "Hamzter" Cinense

1991 Infiniti G20 w/JDM SR20DE

Eclipse CD8445

MTX Thunder 684

Polk DB6750

Polk DB6500

Optima Red Top in the Trunk

forbidden

Platinum - Posts: 5,352

Joined: November 01, 2003

Location: Alberta, Canada

Posted: June 09, 2007 at 2:06 PM / IP Logged

Before you jump on the headunit, what about the rest of the system? Are you using amplifiers in this system? Where are they grounded to? Is there a RCA cable that is pinched?

Top Secret, I can tell you but then my wife will kill me.

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