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Moved my computer from trunk to under the seat, now there's ground noise. WTF??

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  • Moved my computer from trunk to under the seat, now there's ground noise. WTF??

    I had my carputer working fine in my trunk for close to 3 months. All the sudden i started having drive errors and finally a crash. I assumed this was because i had the computer attached to my sub box. So i decided to hack up my case so i can install the carputer under my passenger side seat. I rerouted all cables, shortened the ones that could be shortened, and hooked everything up exactly as it was in the trunk. Now all of the sudden i have inverter buzz coming thru the speakers. I've tried different configs including grounding the case but it all results in the same thing. If i disconnect the left rca plug the buzz goes away but there is still some distortion coming right the right speakers. I really cant think of anything that would have caused this. The ground is connected to the same point. Here are my specs:

    Epia 800
    200watt morex PSU hooked to 400 watt inverter ( + run to battery grounded at passenger seat anchor)

    Please help me to solve this pretty strange issue.
    mp3Car.com Senior Tech Blogger (Want a product reviewed? Contact me.)
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  • #2
    One idea: have you verified that you have as good of a ground connection at the new location as with the old location? Measure with a multi-meter and compare the results.
    EPIA Nehemiah M10k, M1-ATX, 20GB 4200 RPM 2.5", 256MB RAM, Win XP Home, Gyration RF Keyboard & Mouse, Zoltrix Nightingale Optical 4.1 PCI Sound Card, Lilliput 619GL-70NP, XM-PCR w/ optical upgrade, Garmin GPS-25LVS, Microsoft MN-710 USB Wireless NIC

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    • #3
      I'm using the exact same grounding location. The inverter didnt move the rest of the system did.
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      • #4
        is the audio out now significantly closer to the power line?
        "Is Wayne Brady gonna have to choke a b@$#*??!!"

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        • #5
          yes, i now have the inverter in the case with the carputer. could that be the problem?
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          • #6
            Inverters by nature are electrically noisy. Keep it as far away from the computer as possible or get a ground loop isolator for your RCA cables like most people have to do. Cleared my sound right up!
            Rick S.

            XP Pro SP2, Soyo P4RC350 MB, Nvidia FX5200, 320W PS, Inverter & uSDC20D, 2.4GHz CeleronD320, 512MB DDR, 30GB 3.5", Pioneer 106s Slot DVD, Linksys WMP54G WiFi, Lilliput 7" & 4" TFT LCD, Zippy EL610 Keyboard, Touchpad, Garmin GPS V

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            • #7
              exactly. always keep your power lines (especially inverters) as far away from your audio lines as possible.
              "Is Wayne Brady gonna have to choke a b@$#*??!!"

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              • #8
                I moved the computer back to the trunk and the problem is still there. I have two ideas on what it may be.

                1. The AUX in on my alpine headunit is the culprit (either in the headunit itself or the ai-net rca adapter. Looking into my warranty on that product.

                2 Probably unrelated, but my computer only seems to wanna boot in PAL now. I can get to the windows splash screen then the screen rolls. I never had this problem before reformatting. I really know nothin about the PAL/NTSC issue but could it have something to do with the audio distortion? I know the sound drivers are good cause it sounds just fine using headphones or external speakers.

                Are there any jumpers that effect the sound on the 800 board? Maybe one fell off somewhere while gettin the computer in and out of the car.
                mp3Car.com Senior Tech Blogger (Want a product reviewed? Contact me.)
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                • #9
                  I had a lot of noise problems with my computer close to my inverter. What solved it was grounding the case with speaker wire, and 10 gauge wire. And then using some speaker wire and grounding the connections on the rca cable to the frame while using a ground loop isolator. Might want to try grounding the metal connections on the rca/alpine connection.

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                  • #10
                    Lemme explain further about the noise i'm hearing. Its not inverter buzz, whine, or pop. It sounds more like the polarity on the speakers is reversed. I dont think the distance to the inverter is the problem cause moving the computer, wires etc doesnt seem to effect the amount of distortion.
                    mp3Car.com Senior Tech Blogger (Want a product reviewed? Contact me.)
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                    • #11
                      I had a similar problem with another audio in on a headunit.

                      On the rca cables, ground the negative, or the outside metal round tab.

                      I wrapped some speaker wire around the gold connectors on the rca cable and grounded it to the frame, and grounded the case with both speaker wire and the 8 guauge wire.

                      It worked great! give it a try maybe.
                      (\__/)
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                      • #12
                        if you're able to take it out of your car, take it inside and plug it into some speakers. might be able to narrow it down to the soundcard if the sound continues. if not, i'd plug something into the head unit (like an ipod) and see if the sound continues...

                        baby steps.
                        "Is Wayne Brady gonna have to choke a b@$#*??!!"

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                        • #13
                          The only other external device i have is a portable dvd player. I hooked that up and there's alot MORE ground noise, so much so that i cant tell if the same distortion is present while sound is playing. I brought the computer n the house and hooked it to computer speakers and it sounds fine. I will try to ground the out rim of the rca's today to see if that makes it any better. The case is already grounded.
                          mp3Car.com Senior Tech Blogger (Want a product reviewed? Contact me.)
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                          • #14
                            Tried grounding the RCA and the problem is still there. I wasnt positive on how to ground them but i grounded the tab on the male end as well as the rim of the female in. Neither one worked. I'm really starting to think its an issue with AI-net or the adaptor ( i HOPE its the adapter, 14 bucks vs. 400 head unit). I'll order another adapter and post my results.
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