Reflections of a new Jobo CPA-2 owner
I bought a virtually new Jobo CPA-2 processor last week. The owner bought it but never used it. I bought a new 3010 Expert drum for it separately. It didn't take long for me to come to some conclusions about it and it's operation and also about its U.S. distributor - Omega/ Satter.
1) First, I see many people saying that you should absolutely get the foot pump for the Expert drum but some of them warn that if you aren't careful, the lid can blow off and one guy even says he lost a tooth doing it. Others say they damaged their expensive Expert drums with the foot pump. Even Jobo warns about this. It quickly became apparent to me that not only do you NOT need a foot pump, but there is a much better and less expensive alternative. Air compresses and, as pressure builds up, the top pops off - possibly suddenly and with force. But water doesn't compress - at least as a practical matter for this application. So I just went to my local hardware store and got a 50 cent rubber stopper that fit the drum's opening and a piece of brass tubing that fit my darkroom sink hoses. My hardware store had stoppers with and without a hole in the center. Either one is fine but I got one with the hole because that would help keep a drill bit on track when I bored it out to fit the tubing. I drilled the stopper a size smaller than the O.D. of the tubing and inserted the tubing into the stopper. It's a tight, firm, non-slipping fit. The tubing can be plastic, copper, or brass but my hardware store only had it in brass. (See the attached picture.) The black hose you see on the end of the tubing that will go into the 3010 tank lid is not necessary. I just clipped a bit off my sink hose and put it on so that it would avoid any possibility of scratching the tank as I inserted it and it also acts to hold the assembly together which is also not really necessary. But the stopper will not slip on the tubing even without it.
To use it, just push it in the tank lid opening and turn on the water. The top pops off perfectly in a second to two. Air is being compressed if you use it this way so it is similar to what a the air pump might do but probably a bit more gentle. But if you want a perfectly smooth lift off of the top, just hold the stopper loosely in the tank hole and fill the tank with water. When the tank is full, just press down on the stopper and the top will lift off beautifully with no pop at all because no air has been compressed. The water lifts it perfectly. Air acts like a spring and when the top breaks free, it can pop. But water just lifts it up gently.
If you really feel that you need to get a foot pump, which is less convenient and costs about $50 with shipping, you can get an almost identical one from any big store like Walmart. They are used for filling air mattresses, etc., and they are probably better than the Jobo foot pump. But unless you don't have a water hose in your darkroom, I can't see why you would want to do it that way.
2) My new Jobo does not control the temperature anywhere near the claimed + or - .2 degrees. Even when it has been running for 2 or 3 hours or more, the temperature shifts by + or 1 or even 1 1/2 degrees. That's not acceptable to me. The temperature control has far too much slop in it. You have to turn it several degrees for thermostat to turn the heating element on or off. So.... last night while half asleep, something dawned on me. I thought that I could solve this problem if I could use my commercial hot water temperature recyler instead of the heating setup in the Jobo. I have attached a picture of the unit I have. You can find them on eBay for about $100 or even less. It turns out that it uses the same size hoses (5/8" I.D.) as the drain valve on the main (black) reservoir of the Jobo. So now all I needed was a place to insert the other hose at the other end of the Jobo reservoir. So, as a test, I just hooked up the "out" line of the hot water recyler to the drain valve on the Jobo and I inserted the "in" line in the far right-hand bottle holder slot. It works beautifully and the hot water recyler really does keep the water within + or - .1 degrees. It has one rough temperature adjustment and one fine adjustment knob and it controls the temperature with great precision unlike the rudimentary control on the Jobo. In addition, it pumps a lot of water so the water is mixing up far better than it does with the Jobo setup which relies on just the pump bringing water to the upper tempering bath and then letting it drop into the lower reservoir. That can result in uneven temperatures in various areas of the main reservoir and it explains why I was measuring uneven temperatures in the reservoir with the Jobo system. Now my Jobo truly is maintaining its temperature with precision. I know that CPPs have a better temperature control; they have a temperature sensor which is good but they still have the poor water circulation that the CPA-2 has. My next step will be to simply but another drain valve on the right-rear of the main reservoir and hook up the hoses. The hoses can simply be removed and the valves shut if I should want to use the unit as it was designed. Only one modification is made to the Jobo and it has no effect on the Jobo's normal operation if I should choose to use it as it was designed. An additional benefit of this setup is that the hot water temperature recyler brings the temperature up MUCH faster than the Jobo heating element.
3) That brings me to the third thing I have learned since getting this processor. That is, that Omega/Satter is miserable as a supplier of parts. I contacted them because I need one of the special thumb nuts that hold on the motor assembly. One was missing on my unit and probably fell off in the shipping box. You don't really need the "special" nut but it's nice to use factory replacements when possible. Omega/Satter wants $4.95 for the nut (which is O.K.) but they also want $15 to ship it and the ETA will be 60-90 days! But that's not the worst. I also asked them for a price for the drain valve. Get this! They want $49.89 for it! Similar or better valves are available at any home improvement center for $1 - $2. It's just a plastic valve! Guess where I am going to get mine.
Luckily, I have learned about Joboman and also one other parts supplier. The other parts suppler wants $3.68 for SIXTEEN of the special nuts! (.23 each.)
Omega/Satter is engaging in highway robbery, IMO. I won't buy anything from them unless I have no other choice as a matter of principle.
Last edited by ZoneIII; 03-31-2008 at 11:32 AM. Click to view previous post history.