Thanks everyone! Joseph, The timer I am using is a Gralab 500 and I think it can take the load of this lamp, I least I read that someplace. I will open the light up and look inside tomorrow. I am not much of an electrician but I am hoping I can make the fix on the heating elements. This is the 4x5 round lamp. Wish me luck!! Robbie
http://robbiebedell.photoshelter.com
Don't forget the obvious and make sure the heater AC outlet works OK. If the thermostat is bad and not closing maybe you can get a replacement from Aristo. Checking should be easy if you have an AC voltmeter.
Well, I opened it up and this baby is very old. There is a stamp that dates it to April 1983. I am sure parts are impossible to find. It looks like there is a resistor (where the red wires lead). I blew the fuse on my voltometer a while back. Would it be safe just to bypass the relay altogether? I don't know why it would need a relay at all, for something that just stays on for hours and hours. As I said I am no electrician. I am going out to get a fuse, but I can see nothing else that could go wrong. The heater just looks like a plate that sits underneath on the top of the lamp casing. Thanks for all of your patience on this!! Robbie
http://robbiebedell.photoshelter.com
You don't need special compensating timers to get consistent results from a cold light head. All bulbs, even filament bulbs, take time to reach full brightness when power is first applied. If you make a test strip with a series of five second exposures and then pick twenty five seconds as the best time, your twenty five second print will be dark. That's because each of those five second bursts equalled only about four seconds of effective exposure. To make an accurate test strip with any type head, use an audible timer and a large card. Set the timer for the about twice the longest possible exposure so you can see the result of burning in certain areas. For example: set the timer for 60 seconds when making an 8X10. Cover the whole sheet except for one inch. Start the timer and count seven beeps (It beeps when you start) then move the card one inch for the next six beeps and one inch every six beeps after that. The end result will be a ten level test strip of six seconds each from six to sixty seconds. If you then pick thirty seconds as the best exposure, your thirty second print will match the test strip.
Thank you Neal
http://robbiebedell.photoshelter.com
In terms of darkroom equipment 1983 would be pretty recent. The head looks very good inside. So, verify that the thermostat is working, it probably just needs to be adjusted. I'd set it to around 40 degrees C and go from there.
The best way to get consistent results is to use little pieces of paper one at a time. Guess at the exposure and process the little piece of paper, and go from there. If it is too light then double the exposure, and so on. You are going to have to guess the exposure anyway even if you use a 'test print.'
I certainly feel your pain.
I found the problem was the "pattern" of my use...
I used to "focus" and compose for several minutes, then turn off the lamp, take a test strip out and hide it behind my back, hit the "focus" switch for a couple seconds while I aimed and then turn it off and put the test strip on the easel. Then I'd get out the cardboard, hit "expose" and count off a few third-f/stops while moving the cardboard. This tended to make test strips while the lamp was "warm".
Then the lamp would cool down during the next phase of my work which might take ten minutes or so... Develop the test strip (three minutes), stop it and fix for a couple minutes, turn on the light, look at the test strip and think what to do next.
When I'd make a final print the lamp had cooled down. The light changed so the print wouldn't match my guess. Same problem you're having.
---
My "solution" was to put a sensor in my lamphead and connect to an ohmmeter. This gives me a number that relates to lamp brightness. I can watch the number changing and stabilizing and adjust my work pattern to work with the lamp while the ohms reading is fairly stable.
It's improved my consistency, though a bit fiddly to recommend anyone else.
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Bottom line: Pay attention to lamp brightness and how long it takes to warm up to operating temperature. Work with it while it is stable.
It was simple to change my work pattern...
I just turn on the focus for a couple minutes before making final prints... to make the lamp as warm as it was when I made my test strips.
I really like Doremus Scudder's advice to leave the lamp on... But I get squeamish about leaving lamps on.
If I had Bill's ohmmeter, I would just find the point on the ohmmeter where the light stablilizes, and then, before making any test strip or print, simply flip on the light and wait until the ohmmeter showed the light was stable (that's basically what the Zone VI stabilizers do). FWIW, I now print with color heads or a cold light with a Zone VI stabilizer.Originally Posted by Bill Burk
That said, in lieu of a sensor/ohmmeter/stabilizer, just fire up the head 15 minutes before your printing session and turn it off after you make your last print for the day (or turn it off if you are not going to use it for half an hour or more, e.g., breaks). Even with the light on the entire session, it will only be on a few hours a day usually (my longest printing sessions are 6-8 hours, but a lot of that is prep / washing / toning, etc. when the enlarger light could be off).
When actively printing, keep the light on and just keep the enlarger lens capped when not exposing paper. You just need to find a way to deal with timing exposures, not really an insurmountable problem. No need to be squeamish(sorry Bill, couldn't resist)
Best
Again, thanks to all. I checked all of the wiring and measured the current with my voltometer and I am alive to tell the tale. I am just checking the heating wire. It appears that there is power right down to the heating plate that is sort of glued to the top of the lamp just above the bulb. But after plugging it in far a half hour or so there still is no heat the be felt, so I guess that part of the heater is not working even though it has power. I have been in touch with Louise Kessler at Voltarc but am a really getting nowhere. Is anyone familiar with the heating plate and is that something I can find? I think I would be able to replace it if I could get the part. My electrical skills are improving thanks to you folks!! Robbie
http://robbiebedell.photoshelter.com
OK folks. We can end this whole thread as I just have just bitten the bullet and bought a very nice looking cold light, a much newer one, which I will use to replace this old one and hopefully my problems will be solved and I will spend the rest of my days in darkroom nirvana.. I just want to thank all of of you for the advise you have given me. I have visited and looked at the work of those of you who have provided links to your sites, Doremus and Jon. I think it is truly great work. I wish you all the best of luck...Robbie
http://robbiebedell.photoshelter.com
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