Zone VI Compensating Timer Problem - Help!!

[mmcclellan]

I have a Zone VI Compensating Developing Timer with an odd problem. While the "paper" and "real time" settings work perfectly, for some reason the "film" setting has begun acting up - specifically, it times at a very high speed irrespective of the temperature. Even when the temp probe is unplugged, 10 real seconds shows as 30 or so on the timer - the time absolutely flies by!

Any ideas on how to fix this? Since the timer is otherwise working perfectly, I'm hoping there is a way to adjust this, so any advice is much appreciated. Thanks in advance!

[Keith Pitman]

Zone VI used to say, "Guaranteed for Life." Did you buy it new? If so, contact Calumet. In fact, contacting Calumet is probably the best course regardless.

For what it's worth, I've found that my Zone VI compensating timers does not count accurately in "real time" mode. I think everything is consistent so I'm still using it, but may phase it out eventually.

[RidingWaves]

Having had this timer for at least 12 years and using it lots I am always very impressed with this unit. I have had exactly what you described happen, and what fixed it is with the telephone plugs that go into the unit. Take them out and inspect them closely, mine had oxidation inside the clear plastic and I replaced the whole plug with another, done proper with the real phone plug and proper tool to install it. Check also inside the plug to see if any in there as well.

What also happened when I was using the magnetic switch on the temp sensor as the timer Off/On was that the tiny magnet inside the handle part seemed to have lost some of its magnetism, so after establishing proper polarity, I used a small but very strong neodyium magnet to recharge it. I've also replaced the foot switch a few times, now I have a simple toggle switch connected by the same type of phone plug. Now, I use my unit hard, over 10+ years printing, and every time something happens to the unit (every 2-3 years) I think its over, get a new one or find some sort of replacement, but then I fiddle with things and get it to work Again, much to my amazement, and it keeps going.

[Ken Nadvornick]

I'm hoping there is a way to adjust this...

I've owned, an currently use, one of these units for many years. Based on the described symptoms, I don't think this will do it. But it's worth knowing about anyway.

With the front cover in place there are two openings allowing access to a pair of adjustable potentiometers. These are used to adjust the beep volume and (I think, I'm not near my darkroom right now) the display brightness.

But if you remove the front cover you will see another pair of potentiometers below the first pair. These control the timing calibrations for the unit. The right-hand one adjusts the "real time" timer. The left-hand one controls the "compensation" factor. For both, clockwise shortens the timing intervals while counterclockise lengthens them. These controls are very sensitive. An almost imperceptable rotation will result in a noticable change.

To completely recalibrate my unit I will first establish a known 68F/20C temperature. That's usually a small tub of water filled by my Hass Intellifaucet. This water tempering unit is my local standard against which all of my thermometers are compared.

I then first adjust, using the right-hand potentiometer, the base "real time" timing interval by measuring against my wristwatch. I then immerse the temperature probe into the tub and let everything stabilize. Then I adjust the "compensation" interval to match real time as well. This means that when I am timing a 68F/20C process, compensated and real time are the same.

On my unit the compensation varies slightly for paper and film. I do not know if these are intentionally separate curves, or just unavoidable minor slop in the system. But the difference is quite small. Since I develop my films by my own carefully controlled real time/temp, I recalibrate the compensation interval using the "paper" setting only. This is of more use to me in my workflow. I presume a "film" only adjustment could also be made. Or even splitting the difference between them.

I have found that the unit normally drifts over time and must ocassionally be readjusted. To make this easier I have drilled small access holes over both of these previously hidden potentiometers, so that my unit now has four small adjustment openings. This has worked out quite well for me, and the recalibrations, when required, are very quick in actual practice.

Hope this might be useful to you, or someone else.

Ken

[Doremus Scudder]

RidingWaves and Ken,

Thanks for the useful info!

Michael,

FWIW, I had a similar, more general problem which I localized to the temperature probe. I called Calumet and they sent me a new one. It has been working well for some years. Since the connection for the probe and the probe itself work for both "film" and "paper" settings, I would look for the problem inside the unit in the "film" setting pot or even the switch.

I don't know if there is anyone that repairs these anymore, but a call to Calumet might help if you don't want to tackle it yourself.

Best,

Doremus Scudder
www.DoremusScudder.com

[Rick Jones]

I have experienced exactly the same problem in the "FILM" mode. Fortunately, the problem occurs only occasionally and corrects itself by switching to "REAL TIME" then "PAPER" and then back again to "Film". If that doesn't help I would call the Calumet Service Department. As an aside, the internal adjustments to my CDT seem somewhat different than what Ken describes in his post. My REAL TIME pot. causes time to run faster when turned clockwise. The left hand pot. in my CDT does not adjust the compensation factor but simply adjusts the probe time whether set to "FILM" or "PAPER". With the probe in a 68 degree solution if the timing does not run S/A clock time a clockwise turn causes it to run faster and vice versa. The compesation factor in my unit SEEMS TO BE internally programmed.

[Renato Tonelli]

I've had the same problem; Calumet fixed it free of charge.

[Ken Nadvornick]

As an aside, the internal adjustments to my CDT seem somewhat different than what Ken describes in his post.

Hi Rick,

Actually, I think we're both on the same page here.

If a clockwise rotation of either of the potentiometers results in a "shortened interval" between seconds, as I wrote, then this will indeed make the timer appear to run "faster," as you wrote. And the opposite for left-hand rotations.

And regarding the adjustable compensation "factor," your description is much more clear, I fear, than mine. I was trying to say what you said, but it didn't come out as well. Thanks for saying it better.

Years ago I read that the "factor" (i.e., the correcting algorithm, or curve) is indeed internally programmed and fixed. I seem to remember that the unit's film correction was speculated to be based on Kodak Tri-X 320, as were the Zone VI-installed customized filter packs in the modified meters - that being one of Fred Picker's favorite films. But I don't know if this is true or not.

In any case, that left-hand potentiometer does indeed adjust the "compensated" timing interval for both film and paper, as you say. But since the whole purpose of the compensation algorithm itself is to alter that same timing interval for each of those states, I mistakenly referred to the adjustment as being made to that internally-programmed "factor."

Just don't want someone reading this thread down the road from the archives to get confused.

Thanks again,
Ken

[RidingWaves]

Ken, that's great info, I hope I don't have to use it but its good to know, these little units are pretty tough and I think that they were built so its possible to tinker with them and get them running again. I do still think that its a connector problem, and I'd check that out first to rule it out before going deeper.

[mmcclellan]

Thanks everyone!!! Loads of good advice here - tonight I'll get to work using all these solutions and see if I can straighten it out. I absolutely love these timers, in principle. Used one for years, lost it in a move, and just bought another one. The seller (a good photographer) said it was fine just two days before shipping, so I'll be checking the jacks and the potentiometer to see if maybe something got messed up in shipping. IN any case, I'm sure I have enough info from the outstanding APUG community to get it fixed!

Thanks again everyone!!! I'll let you know how it turns out . . . .