Help me decide which Jobo to keep

[nbagno]

I keep finding Jobo processors locally. Yesterday I found a CPA2, latest model (3rd upgrade) really clean, pump is strong, but no lift. I do have a brand new lift that I just bought on ebay, too good of a deal to pass up.

I also have a CPA2 that I also found on Craigslist maybe a year and a half ago, no lift. Bought it really cheap. In both these cases, the owner died and they were being sold off by family members. RIP fellow film processors

Finally my main machine is a CPP2,2nd upgrade with lift. So I understand the differences between a CPP2 and CPA2, slighter tighter temp regulation on the CPP, water inlet, etc. On both the CPP and CPA 2 I end up putting a thermometer in the developer because on both units the dials never match the temperature, they are just starting points. I never use the water inlet.

My thought is to keep the newer CPA2 and put my new unused lift on it giving me a pretty lightly used package. However the CPP2 is the top of the line and it's mentally hard to "down grade". Am I missing something? Too anal? Anyone really care?

 

[Sirius Glass]

Keep and use the CPP2. No discussion needed here.
If you keep both CPA2s you can process stereo photographs.

 

[Neal]

Dear nbagno,

As I understand it, the big difference between the CPP and CPA is the ability to cool the water bath. If you don't need that feature the newer CPA seems a reasonable choice.

Neal Wydra

 

[ic-racer]

I'd keep the CPP2. Are you sure you are using it correctly? The CPP2 bath is one degree C higher than the indicated digital number to account for the slightly lower tank solution temperature.

 

[nbagno]

I'd keep the CPP2. Are you sure you are using it correctly? The CPP2 bath is one degree C higher than the indicated digital number to account for the slightly lower tank solution temperature.

I put the thermometer in the developer and turn the dial until the thermometer settles at 100 degrees. Is that wrong?

 

[Sirius Glass]

The digital temperature control of the CPP2 is worth much more usefulness that having a CPA2. Also the CPP2 will handle Expert Drums; I am not sure about the CPA.

 

[Trainmaster]

Both machines are fine. I have a CPP-2, but you should really get one with the lift. That's the meat of Jobo processing!

 

[sfaber17]

Put the best lift on the CPP2 and then adjust the pots inside to calibrate the unit so the temp readout is accurate. My CPP2 had a bad multi-turn trimmer I had to replace to cure erratic temps. The CPP2 is supposed to have stronger motors than some others, not sure about CPA., then sell the CPA.

 

[nbagno]

Put the best lift on the CPP2 and then adjust the pots inside to calibrate the unit so the temp readout is accurate. My CPP2 had a bad multi-turn trimmer I had to replace to cure erratic temps. The CPP2 is supposed to have stronger motors than some others, not sure about CPA., then sell the CPA.

Is there a procedure for calibration somewhere?

 

[sfaber17]

I couldn't find one on the jobo site. Maybe the ATL ones would apply to some extent. First take the lift off, then take the top off the main unit. You can run it with the top off but use something to divert the water from the pump from splashing where it shouldn't go. You can see the small twisted pair from the thermocouple enter the top right corner of the board near the display. Close by is a single turn trimmer that stands up on the board near the edge and also below that is a 15 turn 1K trimmer pot. Mine was kind of translucent but looked dark inside like it was tarnished. You can spray it with spray cool or dust off and if the temp display goes erratic then replace that. You can get them from digikey (mine is blue). You should measure the resistance of the old one and pre-set the new one so you are in the right ball park. The one-turn stand up trimmer can be used to adjust the temp by a few tenths, which is all I needed. Otherwise you can play with the main 15 turn trimmer and measure at 2 temp points say 20 and 38 deg, and see how the 2 adjustments interact. You may find a slope and intercept effect which will allow you to get it right on.

 

[nbagno]

I couldn't find one on the jobo site. Maybe the ATL ones would apply to some extent. First take the lift off, then take the top off the main unit. You can run it with the top off but use something to divert the water from the pump from splashing where it shouldn't go. You can see the small twisted pair from the thermocouple enter the top right corner of the board near the display. Close by is a single turn trimmer that stands up on the board near the edge and also below that is a 15 turn 1K trimmer pot. Mine was kind of translucent but looked dark inside like it was tarnished. You can spray it with spray cool or dust off and if the temp display goes erratic then replace that. You can get them from digikey (mine is blue). You should measure the resistance of the old one and pre-set the new one so you are in the right ball park. The one-turn stand up trimmer can be used to adjust the temp by a few tenths, which is all I needed. Otherwise you can play with the main 15 turn trimmer and measure at 2 temp points say 20 and 38 deg, and see how the 2 adjustments interact. You may find a slope and intercept effect which will allow you to get it right on.

Thanks for the reply. I just did the single adjustment... I was able to find a CPP user manual with the procedures for both old and new style boards. (Mine's an old style). Adjustment procedure was pretty simple. A lot harder to tell the difference between 32.2 and 32.3 for example on my process thermometer.

 

[sfaber17]

Nice! I googled and found that service manual. It might come in handy. You did the single point procedure. They also outline the 2 point one which uses the other trimmer as I thought. I had the newer circuit board that does the display dimming, but they are similar. That pot. your arrow points to is the one I had to replace.

 

[nbagno]

Working great now that its calibrated.