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  • Screen interferance

    I finally got my Carputer installed. But I do have one problem that I'm not sure how to fix. When the computer is running I get lines that run up and down my screen. I am using the following hardware.

    PC-Chips M863G
    Athlon 4 Mobile Processor 1500+
    256mb PC2100
    geforece fx 5200 128mb graphics card
    200w PSU
    400W Inverter
    La Mobile 7.5in LCD screen

    I had read somewhere that my inverter can cause this problem as it puts out a half sinewave AC current and the computer was built for a full sinewave. The same place also said that this could be fixed by filtering the current before it enters the PSU. If this is correct and my inverter is causing the screen problem, what is the best method of filtering the current? Should I get a different inverter? Any suggestions would be greatly appreciated. Also, I live in the U.S. so it's a 115 volts.
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    1500+ Athlon 4 Mobile
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    ATI Radeon 7000 64mb
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    RentATechnow.com

  • #2
    Anyone have any suggestions??
    ________________________________________________
    Worklog
    K7VTA3
    1500+ Athlon 4 Mobile
    510mb PC3200 DDR
    ATI Radeon 7000 64mb
    [||||||||||] 95% Complete

    RentATechnow.com

    Comment


    • #3
      Welcome to EMC problems!

      Well your theory about the inverter could be correct, but your reasons are a bit off.
      But really it could be from many sources.
      Try moving things, wires connectors, does the interference change?
      How is the VGA cable run? good cable?
      Can you supply it without the inverter to try? (run a cable from the house?)
      Route power cables away from audio & vga cables.
      Check you have no ground loops.

      Hoss

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      • #4
        well I can plug it into my laptop and run on battery power without any problems, but as soon as i plug the inverter into the laptop it starts again. . . So, thats why I think it's the inverter. . . Even when the car is off and I'm running the inverter off of the battery, I still get this interference. I'll try moving the cables around. But I don't think that is the problem as the cables aren't tangled in each other when the laptop is hooked up.

        Update:

        I just grounded the case, PSU, and inverter to the car as was suggested in some other threads. This did not help at all. . . I'm beginning to think that I need a power line conditioner. . .

        Any Suggestions???
        ________________________________________________
        Worklog
        K7VTA3
        1500+ Athlon 4 Mobile
        510mb PC3200 DDR
        ATI Radeon 7000 64mb
        [||||||||||] 95% Complete

        RentATechnow.com

        Comment


        • #5
          Hmm trouble is, if you are getting lines accross the display, then that is at a fairly low frequency (10-500khz), a ferrite on the line will not do much about this.
          It seems like it is the switching frequency of the inverter, prob a low quality design.
          Im not sure the average 'line conditioner' will help this as they are often cheap & arent designed to to this type of filtering.
          You could try running your screen (12v?) from another source (leaving the PC on the inverter supply) this may work.
          But, If it was me i'd be buying a DC-DC ATX supply such as the OPUS or M1 (on this sites shop) - Do it properly

          Comment


          • #6
            Well, the lines are pretty wide about 1/8th of the height of the screen. They travel upward slowly. The screen is a 12V screen desined for a car. The computer is the only thing running off of the inverter. The inverter I have is a 400w Coleman. So I thought that it was if sufficient quality. . . If there aren't any other sugestions, I'll brobably buy a line filter. . . Maybe even put a groud loop isolator on the video cable??? I'm not really sure. If I can't solve the problem I might just buy an opus. the only problem is that my board has a 12v + ATX connector for the processor, I'm not sure the opus has that. . Any suggestions?

            <- That is distracting
            ________________________________________________
            Worklog
            K7VTA3
            1500+ Athlon 4 Mobile
            510mb PC3200 DDR
            ATI Radeon 7000 64mb
            [||||||||||] 95% Complete

            RentATechnow.com

            Comment


            • #7
              Originally posted by S11D336B
              If I can't solve the problem I might just buy an opus. the only problem is that my board has a 12v + ATX connector for the processor, I'm not sure the opus has that. . Any suggestions?

              <- That is distracting
              You seem to have proved it's the inverter.
              If it was me i'd buy the PSU. Anything else is a bodge that probably won't work.

              Comment


              • #8
                I guess I'll just have to get a 200w DC-DC. There's one for $50
                http://www.logicsupply.com/product_i...roducts_id/181

                I could probably modify the cable to supply power to the 12V+ ATX plug on my motherboard. The one that looks like this.



                I already have an ITPS. I'd most likely have to bypass the power regulation as it maxes out at 60 watts if I remember correctly. So I could go ITPS->DC-DC. I'd use the ITPS to start and shutdown the computer. My only question is does the ITPS cut the 12V power after a certain amount of time with the power regulation disabled? I might just need to this one.

                Do you forsee any problems with that?
                ________________________________________________
                Worklog
                K7VTA3
                1500+ Athlon 4 Mobile
                510mb PC3200 DDR
                ATI Radeon 7000 64mb
                [||||||||||] 95% Complete

                RentATechnow.com

                Comment


                • #9
                  I had the same problem occur (the lines in the screen) when I ran a smaller wire from the psu/case to the grounding spot to try to lower hard-drive grounding noise going through the amplifier and out the speakers. It was pretty evident that this caused the problem, as the picture was 100% fine when I removed it. Haven't tried a bigger wire yet that runs away from the vga cable. Still have the ground noise though :-\

                  Could somebody explain the science behind this? Was the noise being introduced to the vga cable by the case grounding wire? Was the case grounding wire not big enough, therefore why the noise decided to *jump* onto a faster ground or whatever. Blah

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                  • #10
                    There are alot of posts describing this. The general consensus is that the ground you are using might not be the best location for one reason or another. Try moving it. the forms for the exact scientific explanation. You said you don't have any noise when you don't use a case grounding wire?? Then just get rid of it, it's not necessary as far as I know.
                    ________________________________________________
                    Worklog
                    K7VTA3
                    1500+ Athlon 4 Mobile
                    510mb PC3200 DDR
                    ATI Radeon 7000 64mb
                    [||||||||||] 95% Complete

                    RentATechnow.com

                    Comment

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