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Thread: major power issue, at wits end!

  1. #1
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    major power issue, at wits end!

    Hi Everyone - I really need some help on this one, im about ready to toss this project out the door!

    A few months ago I setup my car pc in the car, I had a screen flicker, but I didn't have enough time to diagnose the issue, and I dealt with it for a few months, no biggie, I assumed it was just a bad ground.

    Fast forward to today, I switched out the components to a laptop. At first, when I plugged the laptop in without the power cord(running on only battery), I had no screen flicker, and it looked great, but after when I plugged in the dc-dc power cord, I got screen flicker and sound distortion.

    Here are the diagnostic steps I took:

    1) Assuming yet another bad ground, hooked negative lead directly to negative post on battery, still flicker and sound issue.

    2) Thinking that maybe there was an issue with the positive distribution block, I hooked the positive lead to the positive post on the battery... same results.

    3) I removed all VGA extension cords and moved the main VGA cord away from anything that could cause interference and plugged the laptop in directly with the power source, still flicker/sound.

    4) Tried an inverter and regular power adapter, still flicker

    5) Hooked up the dc-dc power adapter up through an m2-atx power supply... still flicker!

    6) Hooked up DC laptop power adapter to the battery on friends car... NO Flicker.

    If I run the laptop on battery, no flicker! or off of another power source, no flicker! So this leads me to believe that theres something inherently wrong with the power source on the car... or something... the flicker and sound issue doesn't get any worse when the car is cranked on and running/accelerating... can anyone shed some light or have any ideas on how I can approach the next step?

    Between the flicker and the sound issues... its almost time to toss the system.. help!

    Thanks
    Jon

  2. #2
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    I'm going to be performing the 'Big Three' soon, and I'm curious if you have.

    From what I understand, the true ground of a vehicle is the alternator - testing using the negative post of the battery wouldn't get around a bad vehicle ground as the rest of the car is still grounded unless you detach the battery posts.

    Have you tried just running off of the battery (ie: unplug the car), or is it any different when the car is running (ie: alternator feeding power)?

    I'm not an authority on the subject but I have a similar headlight flicker issue at low to mid RPM, and I'm going to try to get rid of it by upgrading my ground wires within the engine.

  3. #3
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    I'll try grounding off the alternator and the car battery being disconnected from the car today

    what is the big three?

    Thanks for the help!

  4. #4
    North of the land of Hey Huns
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    The big three, if I remember correctly, are the battery ground to chassis, chassis to engine block, and alternator to chassis.
    "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
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  5. #5
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    I'm pretty sure the 'big three' is just a nickname some mechanics call a particular electrical upgrade - it being an upgrade/replacement of the 3 most important contact points within the engine (alt ground, battery ground, and alt+ to batt+ I think).

    This is one of the best walkthroughs for it that I've found (though I'll likely have it done at a shop as I don't have some of the 'nice to have' heavy duty tools):

    http://www.the12volt.com/installbay/...TID~73496~PN~1

  6. #6
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    Quote Originally Posted by malcom2073 View Post
    The big three, if I remember correctly, are the battery ground to chassis, chassis to engine block, and alternator to chassis.
    Disregard what I said about the + wires (though changing those at same time is not a bad thing), this is the correct 3 spots.

  7. #7
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    It looks like I may need to go that route, I'm going to start by replacing, or adding to the grounding cable, if that doesnt do it, then ill move on to the power from alternator to battery, I figure I should just do it in steps

  8. #8
    FLAC
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    This is a ground loop problem. I fixed my ground loop issue by powering and grounding my screen by the computer's power supply. Unfortunately, you're using a laptop.
    My Nearly Complete Car:
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    Website: (It's a work in progress, really. All my projects have taken me from ever really developing it.)
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  9. #9
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    Quote Originally Posted by PaulF View Post
    This is a ground loop problem. I fixed my ground loop issue by powering and grounding my screen by the computer's power supply. Unfortunately, you're using a laptop.
    My liliput screen is actually powered and grounded to an m2-atx power supply already, separate from my laptop, which is also now currently powered by another m2-atx power supply.

  10. #10
    FLAC
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    Quote Originally Posted by ideal2545 View Post
    My liliput screen is actually powered and grounded to an m2-atx power supply already, separate from my laptop, which is also now currently powered by another m2-atx power supply.
    And this is causing a ground loop between the VGA cable and the ground. Try hooking the screen up to the same M2-ATX that is powering the laptop.

    The ground loop may also be due to the audio equipment you have the laptop hooked up to.

    It can actually come from any accessory hooked up to the laptop and powered separately.

    What do you have hooked up to the laptop?

    PS. How are you powering the laptop of an M2-atx? You don't see many laptops that require a 12 volt input...
    My Nearly Complete Car:
    http://www.mp3car.com/vbulletin/show...ed-car-pc.html

    Micro Control Center... Control Your Car Across the Internet
    http://www.mp3car.com/fusion-brain/1...-internet.html

    Website: (It's a work in progress, really. All my projects have taken me from ever really developing it.)
    http://paulfurtado.com/

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