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  1. #1
    ic-racer's Avatar
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    Converting Super Chromega II to 120V

    This project is about fixing up a surplus Omega Super Chromega II head without power supply.

    The plan is to eliminate the power supply and plug straight into a standard timer.

    If all goes as planned I'll probably donate to a local fellow APUG user that is just starting a darkroom.

    Many thanks to BobNewYork for donating the Chromega for this project.

  2. #2
    ic-racer's Avatar
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    Without a power supply, what is missing?

    Well, the bulb is 24v and the 'standard' power supply ( 412-021) is just a box with a 24v transformer. I can get a 10A 24v transformer from mouser for about $12, but then I'd need a box and a 6-pin female connector and some AC sockets. Alternatively, I could seek a busted power supply for free or $10 and just use the box and the sockets.

    Perhaps the cheapest way is to try and change the bulb to a 120V bulb.

    The specs on the original bulb are:
    ELC

    BASE:GX5.3

    WATTS:250

    VOLTS:24
    MR16 Halogen

    It happens that the EXX
is 250W and has a GX5.3 base. It runs from 120V

    So, it seems that bulb can just plug right in.

    All I need to do is wire a cord straight to the bulb.
    Then, remove the cord with the 6-pin connector and wire a second cord for the fan and utility lamp.

  3. #3

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    The fan in the Chromega head unit off a D5XL that I have is 120 vac. I didn't check the wiring for the small bulbs.

  4. #4
    ic-racer's Avatar
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    Quote Originally Posted by Bob-D659 View Post
    The fan in the Chromega head unit off a D5XL that I have is 120 vac. I didn't check the wiring for the small bulbs.
    Yes, and it looks like the small bulb is 120VAC also.

    I just opened it up and even though there is a 6-pin connector on the end of the cord, it is a 4 wire cord:

    Green = Ground
    Black = Hot 120 VAC
    Red = Hot 24VAC
    White = Common

    The wires go to a buss bar using spade connectors. Things are a little tight because the fan is right there.

    To re-wire it would involve running two 3-wire cords and re-doing some of the spade connectors so it would be theoretically a reversible modification, or at least look like factory-original wiring. Though, I will need to make an additional hole in the chassis.

  5. #5
    ic-racer's Avatar
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    Fan: gets one wire from Black and one wire from White
    Small bulb: gets one wire from Black and one wire from White (though both wires going to the bulb are physically black).
    Main Bulb: gets one wire from White and one wire from Red.

  6. #6
    ic-racer's Avatar
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    Some mechanical problems to manage:

    Rear panel caved in like it was dropped.
    Some numbers are worn off the number wheels.
    All the foam is gone.
    Magenta does not 'zero.'
    Small bulb is gone.

  7. #7
    ic-racer's Avatar
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    Now if I can find some batteries for my "D" camera I'll post some pictures.

  8. #8
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    My chromega head refurb efforts

    Quote Originally Posted by ic-racer View Post
    Some mechanical problems to manage:

    >Rear panel caved in like it was dropped.

    can be fixed; pound it out once all is disassembled

    >Some numbers are worn off the number wheels.

    redo with a sharpie once all filters are aligned, or when all wheels are out; swap the cyan wheel as an option

    >All the foam is gone.
    replace it; any old camera reair skill is easily scaled up here.

    >Magenta does not 'zero.'
    I changed the spring in mine to swap it with the cyan spring, since Cyan never was stretched/used.

    >Small bulb is gone.
    try old sewing machine bulb; I am pretty sure it is the same base and envelope; you may need a resistor in line to cut the amount of light it emits though
    my comments are buried in the quote above
    my real name, imagine that.

  9. #9
    Steve Smith's Avatar
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    Quote Originally Posted by Mike Wilde View Post
    you may need a resistor in line to cut the amount of light it emits though
    Or a diode if you are running on AC. Something like a IN5404 will do. A resistor will dissipate the same power as the bulb and will get hot a diode will not.


    Steve.

  10. #10

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    Dear ic-racer,

    I actually modified an old Chromega head once. I'm pretty sure you will need a different socket for the 120V bulb. They are pretty easy to come by. Everything else is pretty straightforward.

    Neal Wydra

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