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Thread: Generic LCD display, PC TV-OUT issue, all other inputs fine...

  1. #1
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    Generic LCD display, PC TV-OUT issue, all other inputs fine...

    Hi,

    Ive been tinkering with the idea of building a car PC for quite a while now, but recently I got an LCD screen extremely cheap and then discovered the awesome "sygic" drive and so decided it was worth a day or two of my time to build one.

    I used general parts I had lying about and mounted the PC in a custom box. The LCD screen only has an RCA tv signal yolky in, so I put a SIS 315 TV-out card in the PC for the screen output.

    I built the PC in my garage and used an old tv for testing it. All worked fine, but when I put the PC in the car, the screen doesn't see the input, and just shows its standard blue screen.

    Ive tried a PS2 and a DVD player, both worked fine. I also have a reversing camera in the car which works perfectly.

    I tried the PC on three different TV's, all of which worked. Ive spent about a week now, staring at this bloody thing trying to figure out what the hells wrong with it and im jsut drawing a blank!!

    Ive tried the graphic card in NTSC and PAL mode, neither worked on the screen (the LCD display takes both).

    This nearly has me in tears at this stage! esp since ive wired everything into the car and havent had a chance to test it yet :'(

    Has anyone any idea what-so-ever could be the issue?? Im using the same cables for all the tests, so I know their fine too.

    Oh, and the pc works fine in the car tested with an ordinary monitor to make sure it wasn't a PSU issue.

    Any replies are appreciated, im stumped!
    Muxer

  2. #2
    Variable Bitrate
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    Szeged, Hungary
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    Try a 75 Ohm resistor between shield and signal. Sometimes it works, if the problem is the higher resistance of the cable or TV. In this case your PC card does not recognise the TV as a valid TV input at start, because the higher resistance.

    Or, try to boot on an old TV, and when the picture is present and stabile, put the cable immediately into your LCD TV. What happens?

  3. #3
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    Man, you are a legend!!! I want to have your babies!!

    Tried all the local electrical shops, and even the electronic lecturures at the local college. No one had a clue!!

    75ohm resistor worked perfectly!!

    Thanks a lot!

    Also, will be soon posting pictures of the cheapest carputer ever built cost under 400-300 euro for the all the parts

    Muxer

  4. #4
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    Quote Originally Posted by bbalazs View Post
    Try a 75 Ohm resistor between shield and signal. Sometimes it works, if the problem is the higher resistance of the cable or TV. In this case your PC card does not recognise the TV as a valid TV input at start, because the higher resistance.
    This is such a noob question that I'm almost embarrassed to ask it. What do you mean by putting the resistor between the shield and signal. I've got the same problem with my rear headrest monitors not having enough resistance to show up under the display properties. I knew I had to put in a resistor, but I'm not sure exactly how it should be done. I just don't want to screw anything up. Thank for any help you can provide!

  5. #5
    Variable Bitrate
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    The problem is, that the video card is not recognises the presence of a cable or a unit. That tells the TV-out to switch on. The reason of non-recognising is your cable or the equipment at the end of the cable has higher resistance between two wires.

    You have to modify the cable or the unit or the TV-card, as you like.
    The cable has a central wire (also called hot/warm wire) and a shielding around. It can be aluminium foil or copper net. So you have to connect the warm wire to the shieldings via a 75 Ohms resistor by soldering. You can do it inside the connecting plug, you can make an 'adapter', if you like.
    Alopecia perniciosa

  6. #6
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    Quote Originally Posted by bbalazs View Post
    You can do it inside the connecting plug, you can make an 'adapter', if you like.
    How, exactly, would I be able to do that inside the connector. I have tried googling for cross sections of rca plugs, but come up empty. Any light you could shine on that would be greatly appreciated!

  7. #7
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    There are two main types. The one that can't be disassembled (solid, covered fully in plastic). If you have one like that you have to make an adapter.
    The other type is easy, just turn the end of the plug vs. the neck of the plug many times...and voila! it is open.

    In the first case you have to insert an adapter between cable and TV socket, that does not contain anything else, just a male and a female socket, wired directly into each other (central to central, shielding to shielding) and between the central and shielding, there is our famous 75 Ohms resistor.
    Alopecia perniciosa

  8. #8
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    Cool! I'll give it a try. Thanks!

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