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Thread: Intellivision PAL AV Mod

  1. #1
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    Intellivision PAL AV Mod

    PAL Intellivision AV Mod

    Parts Required:
    • Small piece of Vero board
    • 1 x 82 ohm resistor
    • 1 x BC547 transistor
    • 1 x 1N4148 diode
    • 2 x RCA sockets
    • Hook up wire


    Creation of the circuit

    The schematic for the circuit, and diagram for assembly of components on a small board are below




    There is plenty of room inside the Intellivision to mount the circuit, so you can use a bigger piece of Vero board if you like.

    Solder the components into place as per the above picture.

    Console Modification

    Flip your Intellivision upside down and remove the 6 screws.



    Now remove the screws, joystick connections, power connector and ribbon cable as marked. Be careful with the ribbon cable, as it is quite delicate. Be sure to remember which way the connectors and plugs are attached for re-assembly.



    Now remove the shielded console motherboard.



    See how the 2 parts of the shielding are soldered together. To pull it apart make sure you have a decent size tip in your soldering iron. Melt some new solder into the existing solder, that will help being able to melt the existing solder. As you do this to each point, use a screwdriver to prise up each solder point gradually. You may need to go round twice to complete this, as the first few points you raise will only be able to go up a few mm.



    On the underneath of the motherboard, run wires from these points to be connected to the circuit (refer to the diagram above)



    Turn the board over, and connect the audio to the leg as marked. Also connect a couple of wires to connect the RCA sockets to ground. There are several points you can use, just use a continuity test on a multimeter to find any point which connects to the solder points for the metal shielding case.

    Place the metal shielding back on the motherboard. It is recommended to run the wires out as follows near the ribbon cable and power connection:



    At this point you can put your Intellivision back together without placing the top case on and solder the audio & video RCA connectors on to test the mod to see if it works.
    If your mod is working, it is time to place some holes in the case for the RCA sockets.




    For ease of use I put the holes on the left hand lower case. Some people prefer these to be on the rear of the console, it comes down to personal choice. I place some painters tape over where I am going to cut the holes, and mark out the exact hole size.




    Solder the metal shielding back in place on the motherboard, and place it back in the Intellivision shell. See where the wires have been routed near the ribbon cable, underneath the power supply and into the empty space on the left hand side of the console base.




    Using double sided tape, the circuit is attached on the left hand side of the empty space just below the power supply. Place the RCA sockets in the case, then cut the wires to the exact length and re-solder into the sockets. Don?t forget to re-attach the joystick plugs, ribbon cable and the power supply plug, ensuring you have the correct polarity.




    Reassemble the complete console. Make sure you don?t pinch any cables when doing so, as this may cause the console to not work. Test once again, and that is the mod completed! Although simple this mod gives a greatly improved (excellent) picture when compared to RF.

  2. #2
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    great write up here, well done, thanks for sharing
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    Agreed, very nicely done. Easy to follow and very detailed. Thumbs up.
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    Another good writeup. Mate you are putting me to shame. I need to get my hands on some more consoles to hack. Unfortunately INT are not that hard to come by.
    So you are happy with the picture?
    Mine one came out excellent. Very happy with it.

  5. #5
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    Quote Originally Posted by mamejay View Post
    Another good writeup. Mate you are putting me to shame. I need to get my hands on some more consoles to hack. Unfortunately INT are not that hard to come by.
    So you are happy with the picture?
    Mine one came out excellent. Very happy with it.
    Yeah, the picture is very good, can't really fault it.

  6. #6
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    Do you know if this mod can co-exist with the System Change mod? MJ modded my INTV for composite a/v last year and did an excellent job and we are going to try the system changer mod http://wiki.intellivision.us/index.p...t_Modification shortly but not sure if it wil effect the composite output? Any feedback would be greatly appreciated.

  7. #7
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    I haven't put any thought into this on the technical level, but I would not be surpised if this mod did not work with a system changer. It would be worth asking the question at a specialised Intellivision forum I reckon.

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    Cheers.

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    Any better mod available?

    the intellivision av mod only looks great on tube tv sets. on plasma and any modern tv it looks very ugly. I've modded several intellivisions and all the time people complain about the worse output. I've tried several different mod's including this one and of course good on tube, bad on modern tv sets.

    What wrong with it?

    1. color bleeding, you can not play without getting headache
    2. color rolling between brightness colors. typically on "frog bag" with a very brightness playfield the sea, the trees and even the highscore table rolls on it's edges. instead of steady color you'll get pixel artefacts between different colors - typically an AV limitation which can only be solved by altering the signal. It looks very ugly and the noise and static in the background renders the picture worser than HF-modulator output. it seems the power source is not very clean and after the pair of LM chips you will notice additional signal noise in the video signal which finally leads to this bad output. you do not notice it if the playfield is dark (like deamon attack). On donkey kong you will see rolling colors in building construction and swimming playfield, mario is one "soup" of pixels.
    3. colors are not "correct". even the start screen from pitfall differs completely from hf modulator output.
    4. on some games the output looks like small blocks (pitfall) which is typically if the output impedance is wrong. you also notice that on bad Atari AV and S-Video implementations.

    that's why people are looking for new mods for the Intellivision. so finally the only solution is currently the RGB mod which removes the root problem of the video circuit.

  10. #10
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    Great write up

    Thank you


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