? for the electricians, engineers

Discussion in 'Darkroom Developing and Printing' started by j, Jul 29, 2006.

  1. j

    j Guest

    I have a Chrometrol (Chromega control) power supply for the Chromega D5
    head.

    If I turn it on when the Focus switch is on, the high-temp wires that
    connect the bulb will arc to the closest piece of steel, and burn into two
    parts. I've replaced the wire three times already.

    If I turn it on with Focus off, then everything works just fine. Timing is
    good. No arcing. (Yep, I know, "Just don't leave Focus on!".

    Is there a single part in the supply I might replace to fix this? There
    appears to be a large capacitor. What I know about electricity is nada.
    Input would be appreciated.
     
    j, Jul 29, 2006
    #1
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  2. j

    Bob AZ Guest

    These power supplies/timer had little adherence to any standards for AC
    wiring and as a result things can go bad, particularly when used with
    different heads that were not wired as they should be. The only
    solution I have ever found is to go through and straighten up the AC
    wiring. And then address the problem you have. There should be no
    arcing that you describe because the bulb wiring is 24 volts AC.
    Usually.

    Sometimes there is a stabilizer used with the Chromegatrol but you did
    not mention having/using one.

    Also the head could possibly be your problem.

    I don't recall ever having to replace any capacitors. The regulator in
    the Chromegatrol is the usual problem.

    Find a technician who has the schematic and understands how Omega does
    things.

    Bob AZ
     
    Bob AZ, Jul 30, 2006
    #2
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  3. j

    Greg \_\ Guest

    Or doesn't, Omega quit making that version of the Chromegatrol
    4 years ago, they don't even work on them-"No parts" :)
     
    Greg \_\, Jul 30, 2006
    #3
  4. I wonder if the schematic for this thing is available
    somewhere. If the wiring is carrying only 24 volts its hard
    to understand how there could be an arc-over. Also, I don't
    understand what the orignal poster means by "high voltage
    wires", Presumably, nothing in this system shuold be
    carrying more than line voltage. The one possibility is an
    arc caused by an inductive load without some sort of arc
    suppressor. This sort of impuls discharge can burn out the
    contacts in switches but arcing from wire is hard to
    understand. I think there is quite a bit of missing
    information here.
     
    Richard Knoppow, Jul 30, 2006
    #4
  5. j

    Greg \_\ Guest

    When Omega was repairing Chromegatrols we used to see
    a fair number rewired incorrectly by "users." Sometimes this rewiring
    caused shorting. Sometimes the Chromegatrol's need new relays there
    are two types -one that lays on its side another stands upright the one
    that is correct is based on serial number. If the capacitor is bad IIRC
    the unit won't function. The switched go bad, the buttons go bad etc.

    The biggest problem is getting the PCB am not even sure if its
    available anymore-but surely someone that does know electronics could
    find the components.
     
    Greg \_\, Jul 30, 2006
    #5
  6. Even if the PCB is no longer available it may be possible
    to duplicate it, if its not too complicated, using one of
    the PCB kits available.
     
    Richard Knoppow, Jul 31, 2006
    #6
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