Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: How to ground a macmini for carputer?

  1. #1
    Newbie cyruslow's Avatar
    Join Date
    Feb 2007
    Location
    Singapore
    Posts
    5

    How to ground a macmini for carputer?

    Hi,

    Sorry if it sounds stupid but i was wondering on how to ground my macmini?
    I am trying to resolve the whining noise when my mac volume goes higher than 50%

    Right now what i am using
    18.5v 4a power supply
    3.3k resistor tapped to isense

    my other alternative is to have a ground loop.

    Thanks!

  2. #2
    QCar Creator Jirka Jirout's Avatar
    Join Date
    Jul 2005
    Location
    Netherlands
    Posts
    590
    Forget grounding and get a ground loop isolator. Something like this: http://www.radioshack.com/sm-see-all...i-2062214.html (I know this particular one is out of stock).

  3. #3
    Newbie cyruslow's Avatar
    Join Date
    Feb 2007
    Location
    Singapore
    Posts
    5
    Quote Originally Posted by Jirka Jirout View Post
    Forget grounding and get a ground loop isolator. Something like this: http://www.radioshack.com/sm-see-all...i-2062214.html (I know this particular one is out of stock).
    thanks Jirka.
    appreciate the quick response.

  4. #4
    FLAC W3bMa5t3r's Avatar
    Join Date
    Apr 2006
    Location
    Washington, DC
    Posts
    1,268
    Ground Loop Isolators are really just bandaids (and still don't always fix the problem). Go after the real culprit and try grounding the system first. I can't offer any info as to where at on the minimac to attach the ground to as I don't have one, but attaching to metal on the chassis, say a screw that goes from the case to the motherboard mount or something similar should be good.

    A great guide written by a member here
    Induced noise/Ground loop trouble shooting guide.


    Good luck and Cheers

  5. #5
    Constant Bitrate
    Join Date
    Jul 2006
    Location
    London
    Posts
    129
    I wouldn't be looking at the mini, but more the audio you have fitted in the car....!!!

    It is very unlikely the signal is bad coming out of the mini...!

    Check it by running computer speakers plugged in while in the car on the drive and if it whines then it is the mac, if it doesn't then it is the audio....!
    CLICK ME

    Smart Car due for completion beginning of march....

    Log with pictures to go online shortly after.

  6. #6
    CarFrontEnd Creator iamgnat's Avatar
    Join Date
    Jul 2004
    Location
    NoVA
    Posts
    867
    Quote Originally Posted by www.workingcars View Post
    Check it by running computer speakers plugged in while in the car on the drive and if it whines then it is the mac, if it doesn't then it is the audio....!
    Actually I found that using my iPod did the trick when I installed mine (e.g. take the Mini out of the loop).

    Given that you custom built the cable, i'm going to go with it as the first thing to look at. Either your connections aren't solid, or in striping it for your connections you've exposed it to interference by removing the shielding (maybe from your power supply itself?).

    Another idea for isolation is to run an extension cord out from the house and run the Mini off A/C. If the noise goes away, then it is your cable/power supply.

    Has this power supply been involved in your audio system prior to installing the Mac? (e.g. was it driving a previous computer or something?) You might try moving it's ground wire around a bit too to see if that helps.

    -dave
    My pathetic worklog.
    CarFrontEnd (now it's own sub-forum!!!!)

  7. #7
    Newbie
    Join Date
    Aug 2006
    Location
    Birmingham
    Posts
    20
    If you can determine the problem is in the audio end (I agree it probably is), check the following:

    - If you're using RCA's, make sure the RCA cables aren't running next to factory wiring. If at all possible move it away.

    - At the amp(s), make sure the ground is super tight to metal, you should be able to move or wiggle the ground cable. Scrap away as much paint from the ground spot as you can and use a star washer to really bit into the metal when you tighten it. Keep the ground less than 18"s.

    - Is the amp mounted to metal? try removing it if it is and put it on wood or carpet.

    - Are you also using an after market HU? Make sure it's using the factory ground in the factory wiring harness. If it is try removing the ground from the harness and ground it to the firewall or metal brace in the dash.

    - Has the alternator been replaced? Do your light flash on bass notes? May have a battery going bad, go to an auto parts store and ask them to load test it.

    HTH,
    B.

  8. #8
    Newbie cyruslow's Avatar
    Join Date
    Feb 2007
    Location
    Singapore
    Posts
    5
    thanks mate. i will try doing this 1st. appreciate ur reply.
    cheers
    cyrus

    Quote Originally Posted by W3bMa5t3r View Post
    Ground Loop Isolators are really just bandaids (and still don't always fix the problem). Go after the real culprit and try grounding the system first. I can't offer any info as to where at on the minimac to attach the ground to as I don't have one, but attaching to metal on the chassis, say a screw that goes from the case to the motherboard mount or something similar should be good.

    A great guide written by a member here
    Induced noise/Ground loop trouble shooting guide.


    Good luck and Cheers

  9. #9
    Newbie
    Join Date
    Nov 2005
    Location
    Lion City
    Posts
    24
    Quote Originally Posted by cyruslow View Post
    thanks mate. i will try doing this 1st. appreciate ur reply.
    cheers
    cyrus
    Hello bro from MCS...

  10. #10
    Newbie cyruslow's Avatar
    Join Date
    Feb 2007
    Location
    Singapore
    Posts
    5
    just an update

    installed a ground loop isolator and the noise is removed.
    however, the sound quality of the audio drops drastically. i played the same song before and after the installation.

    guess i have to open up the mac and get do a proper grounding.

    Quote Originally Posted by airspeed View Post
    Hello bro from MCS...
    hi.

Page 1 of 2 12 LastLast

Similar Threads

  1. Induced noise/Ground loop trouble shooting guide.
    By Will Albers in forum Car Audio FAQ
    Replies: 138
    Last Post: 01-28-2011, 09:37 AM
  2. Alternator Whine Only With Carputer
    By tbird2340 in forum Car Audio
    Replies: 25
    Last Post: 06-29-2007, 03:36 AM
  3. Inverter Question
    By phatchink in forum Power Supplies
    Replies: 27
    Last Post: 08-21-2006, 01:45 PM
  4. I tried everything, can't get rid of this ground loop
    By intense in forum General Hardware Discussion
    Replies: 3
    Last Post: 07-10-2005, 09:58 AM
  5. Pinout Color Codes / Tables
    By gummybear in forum General Hardware Discussion
    Replies: 4
    Last Post: 05-12-2005, 04:05 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •