Anyone using an f-stop timer with a Chromegatrol/Omega Dichroic II head?

[Jerry Thirsty]

Hi all,

I currently run my Omega Dichroic II head from a Chromegatrol (version I). I'm considering getting an f-stop timer, but I've got some concerns about whether the hardware will play nice together. The Dichroic II head has a 6-conductor plug, so obviously I can't eliminate the Chromegatrol and run it directly off the timer. I assume I have to plug the head into the Chromegatrol, plug the Chromegatrol into the f-stop timer, set the Chromegatrol switches to "On" and "Focus", and then run the system from the timer controls. What I'm wondering is whether I can damage my Chromegatrol by toggling it on and off frequently via the main power like that? At a minimum, it seems to me that it will kill the bulb very quickly because the cooling fan in the head won't be on all the time like it is with the Chromegatrol. I've got the circuit diagram, and I work with electrical engineers; they should be able to help me figure out how to rewire the head if I need to. Am I overlooking something? If any of you are running a Dichroic II head off a 3rd party timer, I'd like to hear how you have it set up.

thanks,
Jerry

 

[ic-racer]

The chromagatrol is a valuable item because of its ferroresonant transformer and associated timer. One option is to save the chromegatrol and pick up the old chromega power supply. With a couple shortened extension cords the older power supply can be hooked to just about any timer.

If you really, really want to keep the chromegatrol and use an f-stop timer I suspect you could rig it to run through the foot pedal switch jack. Have the f-stop timer trigger a relay that makes and breaks contact like the 'focus' pedal of the dual footswitch would. (Connecting #1 to #4 on the footswitch jack on the schematic).

I'd just keep using the chromegatrol and get a calculator; 1.185, 1.26, 1.4, 2, etc. (1/4, 1/3, 1/2, 1 etc.).

 

[Nicholas Lindan]

I suspect you could rig it to run through the foot pedal switch jack.

I believe the footswitch for the Chromegatrol was a dual model so that one could turn the enlarger on for focusing. From the schematic I have it looks like shorting 1 and 4 of the footswitch connector should turn on the enlarger lamps.

If that does it, then it is relatively simple to use an external timer. You will need a relay, though.

 

[Mike Wilde]

I run my Dichroic II head by a Lici Colorstar analyser/timer with an Omega step down transformer (don't have the modelk at hand; it is the low market one that just generates the 27 V the biulb needs and sends out the power to the head via the 6 position socket. ) This supply allows the timer to be looped though it to control the bulb. I have a separate ferroresonant TX upstream of all of this.

Hope this helps.

 

[Jerry Thirsty]

Thanks everyone, you've given me plenty to think about.

Jerry