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Omega Super Chromega F dichroic II rewire for 120 v bulbs

Randy Moe

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I am about to rewire an Omega Super Chromega F dichroic II for this, Sylvania / Osram ELH (300W/120V) Lamp, which seemed cheapest from B&H. Of course 4 lamps as original.

I will add a new full circuit overheat cutoff switch at the factory setting of 130 degree F.

Most likely it will be easiest to not wire for the lamp failure lights on the now redundant power supply. I'm splitting the power inside the head.

I am also thinking of hacking a DIY timer as lately I am having trouble with used timers. Since this is 1200 watts I will need a relay anyway.

Any advice is welcome.

Anyone else done this?
 
Lamp Failure

Randy: it sounds like you know your stuff. The relay will be a piece of cake for you. Only comment I have is: (for me anyway) it is difficult to tell when one of the bulbs is off unless the failure lamp lights turn on. If you are going to disconnect this circuitry, this is something to keep in mind.

Have you had the enlarger (head) for long? I have had my Omega F for many, many years and it has never given me trouble. Routine maintenance stuff: changing the styrofoam liners, cleaning, lubing certain parts. Had the dichroic filters changed (about 7 years ago). I understand they are indestructible.

Good luck with the project.
 
Hi Randy,

This seems like an expensive idea unless you already have a nice 120V power supply. If you do have a source of nice steady power, why not simply rewire the entire head for 120V? You'll have a nice clean install and one less transformer to start buzzing as time goes on.

Timer? Every time I look at building a timer, the difference in the cost of buying a brand new one always seems less than my time. I have always thought that a PLC would be the easiest way to combine all the jobs required to control an enlarger and they are really cheap at automation direct. But whenever that idea pops up, I remember that my enlarger works just fine the way it is. <G>

In any case, I actually hope that you build a really cool control system and then post it on the forum.

Neal Wydra
 
I was going to do a 120v conversion on a Chromega D but the cost of the appropriate connectors and sockets to made it more economical to find a power supply to repair. Turns out we got a free Power Tower that was easily fixed with a new SCR. That probably won't happen for an "F" power supply

You can run a fiber optic cable from each lamp to create a series of indicators on the front panel.

(there was a url link here which no longer exists)
 
Last edited by a moderator:
Fwiw, on my fotar/chromega I had to add 4 layers of lee 216 diffusion over the bulbs to get long enough exposure times even at f16 on a 240mm printing 11x14's (b+w). 1200w worth is a lot of light.
Are the original lamps too hard to find?
 
I am rewiring the head for 120V, I thought that was clear.

I am doing this to eliminate the 24 volt power supplies which must be very unreliable as it came with 4 of them. I just don't see the point of running 24 volt. Cost of conversion is minimal.

Primarily my initial problem is/was bad cabling and missing interlock connectors. The seller said it worked as is, but it sure doesn't.

The mixing box is fine, and I am doing only B&W and will use it for 8x10 to 16x20 or larger.

The timer is still a WIP. But I do know it won't be a f-stop timer...

Vinny, I know 1200 watts is a lot of light, my DIY 1000 watt LED head needs to run at 20%. I may use this on a horizontal wall mural projection chassis.
 
Jack Rosa, if I could find new filters I would change them, just because. I need to do more research and perhaps find newer and different sources for these filters. One filter has been replaced and I found the one that fell out, inside the head in perfect condition. I may just clean everything. like I wrote, I will not be doing color and everything becomes relative.
 
Help with Dichoric Filters

Randy: I think it was around 2007 when I had my Omega F head completely refurbished by Focal Point (in FL). Michael Sparks was very helpful and knowledgeable. I would think he would be able to help re: dichroic filters.

His e-mail was mike@fpoint.com and the url was www.fpointinc.com. Hope this helps. Feel free to let him know I referred you.
 
Thanks Jack, I will contact Michael Sparks in the future, I first want to get the conversion done and see how it all goes.

I'm putting zippers on this and it will be faster to pull the lamps out, I had no idea what was holding the whole mess inside on the right side and had to discover the method.

The first time is always the learning curve.
 
Well, I broke it down to small parts, and wow, a lot of dust, large piles of dust, behind the mixing chamber, everywhere. You cannot clean one of these without major disassembly. It has no filter on the incoming suction, but it is easy to add one.
 
Randy Moe said:
Well, I broke it down to small parts, and wow, a lot of dust, large piles of dust, behind the mixing chamber, everywhere. You cannot clean one of these without major disassembly. It has no filter on the incoming suction, but it is easy to add one.
Click to expand...

A filter sounds like a good idea. My Durst 8x10 head has a manufacture date around 1992 and it was pretty clean in side when I got it. Looked like new actually. I did not even touch the filters. It has a panel type of intake filter on the back of the head.
 
I wonder how old this thing is? All battleship grey aluminum. I thought about painting it the more modern black, but rejected that idea as a waste of time and black will simply show more marks and dust. It is of course matte black inside.
 
Air Filtration

Randy,

Mine is also painted battleship gray/aluminum …. the color that was used in 1950s!

I would be most interested in learning how you are going to go about installing an air-filtration method on the incoming (suction) air and would very much appreciate it if you would be willing to share this information.

Regards,

Jack
 
Pretty simple, the main air intake is under the rear square stand-off panel. Very restrictive for some reason, maybe to keep birds out!. I am going to play with several solutions, but the simplest will be a box filter larger than that rear panel that simple mounts over it. I happen to have a 10x20" house furnace filter right here. It's almost the exact size of the rear cabinet, but is too big. I will cut it down into 2 or 3 filters and loosely mount them. Suction should seal them off using the giant squirrel cage fans I got with this. Maybe drill some holes in the panel. I could calculate all this, but intake area is way smaller than the top hose connection, which is also way smaller than the fan intake. A lot of velocity at the filter and inside the lamp chamber. Maybe I will stick a T-couple in there to see what actual temps are.
 
Air Filtration / Air Velocity


Thanks Randy. Only concern I would have would be the reduction is air velocity and its possible effect on cooling the lamp-house. How do you feel about that?
 
You also have to think about light leaks when messing with the air inlet, you don't want to fog all your highlights. My head had significant light leakage at the inlet that I had to make a little baffle out of gaff tape to reduce the leakage. Just a thought.
 
There is an internal light/heat baffle dividing the area behind the mixing box. I think it blocks light and also makes the cooling air run the long way around the chambers. If light is emitting from the rear air intake outside baffle a filter could be boxed to solve that problem. I haven't fully powered up yet. I'm wired, but I ordered new lamp sockets. I got rid of the main power wire hanging out the back and converted to a computer type power socket. Much cleaner and no frayed wires

Heck, I am not even going to use a timer for a while, just let a metronome tick and count off. Finger timer.

I will be selling 4 original power supplies...

Eric, are you still using yours?

 
Yeah Randy, I use mine all the time and am following your progress for when my power supply eventually dies and I have to consider how to best fix it...
Good luck
 
Air Flow ~ Revisited

Am I the only one who's' nervous about air flow / air velocity if a filter (of she sort) is installed? :confused::confused:
 
This fan is a strong vacuum cleaner and vacuum cleaners use filters. I will monitor temps for a while with a T-couple and I have installed a new temp shutdown switch. No worries.

This fan is not a puny computer fan, this one will blow leaves across the yard. I think the OE, if this is OE, fan has plenty of suction. I have used this type fan to remove welding fumes, car exhaust, 1700 degree racing engine header heat on a dyno. I know how to handle hot stuff, this is childs play.

Your fan may not be the same. Since new, I am sure these things have been messed with plenty. My 2 fans for this F weigh at least 20 lbs each.

Look what I'm doing, I'm messing with it. So did everyone else for 60 years.

Next I will change the off balance fan on my Beseler 23. It will get a computer fan, a srong one, but nothing like the F fan. After that, I have plans for an E.

Hey all people do is throw this stuff out, so I fix and use other peoples junk.

JackRosa said:
Am I the only one who's' nervous about air flow / air velocity if a filter (of she sort) is installed? :confused::confused:
Click to expand...
 
Got it. THX

Got it Randy and thanks for taking the time to explain. My fan does not sound as strong as what you have (someone may have messed with the motor before I purchased the equipment) but can clearly see how, with all that sucking power, air velocity would not be an issue. I appreciate you sharing your insight.
 
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