Zone VI Compensating Timer Problem - Help!!

Discussion in 'Darkroom Equipment' started by mmcclellan, Mar 13, 2010.

  1. mmcclellan

    mmcclellan Subscriber

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    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!
     
  2. Keith Pitman

    Keith Pitman Subscriber

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    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.
     
  3. RidingWaves

    RidingWaves Member

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    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.
     
  4. Ken Nadvornick

    Ken Nadvornick Subscriber

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    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
     
    Last edited by a moderator: Mar 13, 2010
  5. Doremus Scudder

    Doremus Scudder Member

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    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
     
  6. Rick Jones

    Rick Jones Subscriber

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    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.
     
  7. Renato Tonelli

    Renato Tonelli Subscriber

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

    Ken Nadvornick Subscriber

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    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
     
  9. RidingWaves

    RidingWaves Member

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    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.
     
  10. mmcclellan

    mmcclellan Subscriber

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    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 . . . .
     
  11. mmcclellan

    mmcclellan Subscriber

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    Ken, et.al.,

    I opened up the timer tonight and adjusted the potentiometers as outlined by Ken and Rick and everything works perfectly - most of the time! I also checked the contacts on all the cables and everything is clean as a whistle. Interestingly, after getting the adjustments made so the timer matched my iPod timer on 68F, I realized as I starting putting it all back together that the problem seems to be in the rotator switch itself! When I pull down on it (toward the base of the unit), it runs normally; push it toward the top of the unit and the film side runs fast. This action does not affect anything else. Other than replacing the switch, any ideas on how to correct that? If I keep having the problem, I will talk to Calumet as several of you suggested. Thanks again!
     
  12. Ken Nadvornick

    Ken Nadvornick Subscriber

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    I've yet to see that symptom, Michael, so I'm just speculating here.

    Since the rotator shaft is by nature exposed to external forces, any chance that a knock in the past - perhaps in the dark - could have cracked the solder joints that hold it to the "motherboard?" It seems from what you describe that perhaps an electrical connection is sporadically failing to make proper contact.

    I suppose it could also be a failed contact within the switch itself. But I would be more likely to discount dirty or corroded switch contacts, as the act of using the switch normally should keep those clean enough, I would think.

    In any case, if you can localize the problem to the switch in question, then perhaps it's fixable by either Calumet, or someone local to you (television repair shop?) who is experienced with circuit boards and has the proper tools.

    A replacement switch can't cost too much. And given the wonderful utility of these units, I'd think be well worth it. I know I couldn't do without mine. Sets of identically exposed prints* always process out identically for me. I love the thing.

    Ken

    * I also use the Zone VI Compensating Enlarging timer. Another fine piece of equipment that has always worked as advertised.
     
  13. mmcclellan

    mmcclellan Subscriber

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    Ken,

    Thanks for the suggestion! I'm a total Zone VI "junkie"so really want to get this right! I was thinking the same as you and will follow up as you suggest. Thanks again!
     
  14. Nicholas Lindan

    Nicholas Lindan Advertiser

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    I would try some contact cleaner as a first try. Dirty switch contacts are, statistically, the most likely problem. Although one might think it, exercising the switch won't clean dirty oxidized contacts - at least not for long.

    If the switch is soldered to a circuit board, and the collar of the switch is not screwed down to the timer's case - then the connection between the switch and the pc board may have broken, as Ken has mentioned. This is especially true if the circuit board is single-sided. What cracks isn't the solder joint but the connection between the land (the round doughnut of copper foil where the 'bump' of solder is) and the trace (the long skinny bit of copper foil that connects to the land). With a 10x loupe you should be able to see the break when you flex the switches shaft. If the land has lifted from the board then the fix is to solder a bit of wire from the land/switch pin to the place where the trace goes to, thus bypassing the crack. Don't try to solder the land back to the trace - the solder joint will just crack open again.

    The next likelyhood is that the switch is broke and needs replacing. If you can post a photo of the switch I may be able to point out a possible replacement.
     
  15. RidingWaves

    RidingWaves Member

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    Wow, I've just learned a bit more about keeping this timer going. Like the DC-9 of timers, or VW bug.