Zone VI cold light stabilizer question..

[Robbie Bedell]

All of you folks were a great help a few months ago when I had cold light head problems. Well, I now am all set up with a like-new ZVI head and new V54 Aristo tube. I got a ZVI stabilizer but I think it has a problem. When using the unit the light flickers. At first this was happening only when the intensity dial was down low, which I might have suspected, but today it started at the higher brightnesses. I switched timers and it still flickered. Then I plugged the head in directly, bypassing the stablizer altogether and the tube lit up steady and bright, with no problem whatsoever. So I guess the problem is the stabilizing unit. I called Calumet and their repair guy who does this work is on vacation, and their electrical repairs are not cheap. Does anyone with experience know if this might be an easy fix or should I just bite the bullet and pay the money and wait the month it will take to get this solved? Any help will be greatly appreciated..Thank you! Robbie

http://robbiebedell.photoshelter.com

[Kevin Crisp]

Is there a timer in this circuit somewhere?

[Robbie Bedell]

Hi Kevin, Yes, I am using a Gralab 500 timer that says on the side it is good up to 700 watts. I switched out that tmer for second one and still got the flickering. That's when I went directly to the wall and got a bright and very steady light..

http://robbiebedell.photoshelter.com

[Kevin Crisp]

Only certain timers can handle it, from what I recall. I've been using the compensating timer so long I can't really recall details, hopefully somebody else will chime in who is still using this device. Good luck.

PS: Loved your web site, very interesting.

[jk0592]

I have had the ZoneVI 4x5 cold light old style, not V54, with the stabilizer for ages now, and always used it with a Gralab 300, and now with a Gralab 505. Both these timers work without flaws with the inductive load of the cold light. The Gralab 500 should handle the load with equal ease.

Is the stabilizer green light on when the flickering starts? Are you bordering on the upper limit? Mine has E or thereabout as an upper limit; I tend to stay a bit lower, at C or D.

[Robbie Bedell]

Yes, the green light is on when the flickering starts. And the green stays on all the way to the upper limit on the dial. It REALLY flickers a lot when at C and D. The new tube is very bright and the stabilizer seems to handle that part fine.

And Kevin: Thank you for your kind words! Robbie

http://robbiebedell.photoshelter.com

[jk0592]

I just went to the darkroom to check the cold light. When at C or D, the cold light itself emits a very faint hum, that I can barely hear with one ear very close to cold light. The hum increases when above E, but is still very faint, almost imperceptible.

Do you get flickering with the stabilizer on, but without the timer ? Or flickering without stabilizer, but going through the timer ?

[Robbie Bedell]

OK, I guess I did not make my case clearly. But I did troubleshoot. I did with and without timer (two of them). It flickered both with and without the timers. The only time it did not is when I plugged the enlarger lamp directly into a wall socket. It was then very bright and steady, with no flickering whatsoever. (the heater cord was plugged in the whole time). So it is the stabilizer. I just want to know if it might be a simple fix that I can do to save time and money. Thanks to all so far! Robbie

http://robbiebedell.photoshelter.com

[Robbie Bedell]

Oh Well. I guess my next question is: Has anyone ever had a stabilizer repaired by Calumet or anyone else?

http://robbiebedell.photoshelter.com

[jk0592]

Wait, I just dug out my ZoneVI instructions (from 1990). Here is what Picker says in the section dealing with timers (I quote) : ..."If the timer switches on, but does not reliably switch off, if the timed interval is erratic, or if the light flickers when plugged into the timer (but not when plugged directly into the wall outlet), then you probably need a snubber circuit."...

Maybe you should try with a different timer model

[Brian Ellis]

Can't help with your problem but wanted to say how much I liked your web site. Particularly liked "Two Men."

[Robbie Bedell]

Brian. Thank you very much for looking at my photographs. Your reply is very inspiring..

J.K. Thanks for your further input. I think that Fred P.'s mention of a 'snubber circuit' is just what is needed here. I tested everything again. With the light strait to the wall, or through either of my two timers, there is no flickering. With the lamp wired to the stabilizer and then to the wall, there is none. Only when the stablizer is used in conjuction with a timer does the flickering start to happen. And then it only starts after a number of exposures, say, after a step wedge. Then it starts and gets worse as time goes on. So now I am looking into snub cicuits. Since I am all thumbs with electricity this should be a daunting task. Anyone know how to wire up a snubber circuit so a dummy can understand?.... Thanks again J.K. ! Robbie

http://robbiebedell.photoshelter.com

[Robbie Bedell]

Well, I do not know what I did. But I must have had something wired wrong. I just went back made sure I had everything plugged correctly and Viola! there is no flickering at all. So I guess nothing is broken, which it good... Beats me what I did..But thank you all for your patience! Robbie

http://robbiebedell.photoshelter.com

[Chuck Pere]

For what it's worth my stabilizer runs at L with a high intensity V54 head. As you turn the knob CW you should find a point that the stabilizer green light goes off and the red light on. I run slightly CCW of that point.