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  1. #1

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    Timer for LPL 4550XLG Enlarger

    I recently bought a 4550XGL enlarger which uses a 250 W bulb. I've tried to use a GraLab model 450 timer with it, but each of the two new units I've gotten failed some of the time to switch off the light. However, the timers (rated for a 600 W load) work perfectly when tested with a regular 100 W bulb. Any ideas what the problem is? If it's the timer, can you suggest one that you know works. Thanks. Rick Durbin

  2. #2
    david b's Avatar
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    I am using a Saunders ET-500 timer without any issue.

  3. #3
    ann
    ann is online now

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    we use a beseler 8187 with ours. we also use 1 250w 82v bulb EVW with everyone with no problems.
    http://www.aclancyphotography.com

  4. #4

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    I have the same enlarger with a foot switch to turn it on and off and a metronome to count down the seconds. Leaves my eyes and hands free to burn and dodge.
    Scott Killian
    www.scottkillian.com

  5. #5
    galyons's Avatar
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    Rick, the bulb is 250W, but 82 volts. The bulb is powered by the transformer which steps down the voltage. The issue may be in the transformer, not the timer. The timer is just providing a time controlled relay to turn power off and on to the transformer.

    Now, my opinion on a timer, get a RH Designs f-stop timer. IMHO, the best tool for fully understanding the relationship between all of the expsoure variables and the image produced.
    Cheers,
    Geary

    Quote Originally Posted by rick durbin View Post
    I recently bought a 4550XGL enlarger which uses a 250 W bulb. I've tried to use a GraLab model 450 timer with it, but each of the two new units I've gotten failed some of the time to switch off the light. However, the timers (rated for a 600 W load) work perfectly when tested with a regular 100 W bulb. Any ideas what the problem is? If it's the timer, can you suggest one that you know works. Thanks. Rick Durbin
    But your flag decal won't get you into Heaven any more. They're already overcrowded from your dirty little war.
    Now Jesus don't like killin' no matter what the reason's for, and your flag decal won't get you into Heaven any more. – John Prine

  6. #6

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    I use a Gralab 550 with my 4550 XLG. While the Fstop timer is a fine piece of equipment, a person can do Fstop timing with a conventional timer.

    I use the same timer to control my 1000 watt point light source lamp. In that case I use the timer to control a relay coil to switch the voltage into the lamp.

    The amperage on a Saunders at 82 volt 250 watt is 3.04 amps. The equivalent of 600 watts at 115 volts is 5.21 amps so the switching relay in the timer you mentioned is being operated within the design parameters.

    Are these new timers that are failing? If so it may be that you have a current leak to ground and that would increase the amperage beyond the lamp current requirements. It would be possible to check for this by taking each of the transformer taps to ground with a ohm meter set on the 1000 ohms scale (unit obviously disconnected from it's power supply). While it is true that the transformer is reducing voltage, it still remains that secondary load on the transformer will affect the primary input amperage.
    Art is a step from what is obvious and well-known toward what is arcane and concealed.

    Visit my website at http://www.donaldmillerphotography.com

  7. #7
    Jeffrey A. Steinberg's Avatar
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    I have a kearsarge (model 300?) timer that works great with it. It is a nice digital timer. Not sure if they still make it.

    --Jeffrey
    --Jeffrey

    ______________________________________________
    Jeffrey Steinberg, K2MIT
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    www.jsteinbergphoto.com (my avocation)
    www.reversis.com (my vocation)

  8. #8
    jp80874's Avatar
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    Quote Originally Posted by rick durbin View Post
    I recently bought a 4550XGL enlarger which uses a 250 W bulb. I've tried to use a GraLab model 450 timer with it, but each of the two new units I've gotten failed some of the time to switch off the light. However, the timers (rated for a 600 W load) work perfectly when tested with a regular 100 W bulb. Any ideas what the problem is? If it's the timer, can you suggest one that you know works. Thanks. Rick Durbin
    Rick,

    I used the same 4550XLG-250w bulb-GraLab 450 for about a year and a half without problem before I moved up to 8x10. The units work together so I would pursue a componet malfunction such as mentioned. It is all still set up if there is anything you want to compare or try, just send me a PM. It simply hasn't been turned on for about 15 months.

    John Powers

  9. #9
    RH Designs's Avatar
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    Quote Originally Posted by rick durbin View Post
    I recently bought a 4550XGL enlarger which uses a 250 W bulb. I've tried to use a GraLab model 450 timer with it, but each of the two new units I've gotten failed some of the time to switch off the light. However, the timers (rated for a 600 W load) work perfectly when tested with a regular 100 W bulb. Any ideas what the problem is? If it's the timer, can you suggest one that you know works. Thanks. Rick Durbin
    I don't know the Gralab 450 very well but if it uses solid-state relays instead of electromechanical ones then the likely cause is leakage in the relay. The LPL 4550 uses a relay built into the transformer, and it requires very little power to operate it. Solid-state relays can leak sufficient current to keep that relay energised once it has closed - this means your timer can switch the light on normally but does not switch it off again because the leakage current is keeping the relay closed. That is an inherent "feature" of solid state relays and the reason we went back to mechanical ones, after briefly using them in our StopClock Professional and Analyser Pro. Both of these products will work fine with your enlarger.
    Regards,
    Richard.

    RH Designs - My Photography

  10. #10

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    If the problem is like what Richard said then you have a few choices.
    1. Buy a different timer with mechanical relay.
    2. Modify the Gralab 450 to have mechanical relay.
    3. Add a light load in parallel with the enlarger to drain the leakage current in the off state. To test if this would work. Connect an extension cord to the timer outlet with 2 outlets at the other end. Plug the enlarger in one of the outlets and plug a small lamp into the other. 10W lamp or so would be fine. Up to 100W lamp should be no problem. If the timer now works correctly then you need to replace the lamp with something that doesn't produce light when power up. I can't think of any good thing to do this except a plain resitor but that would require some electrical work and is not very good for some one who doesn't have the experience.

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