Using "Foreign" Parts In Jobo Unit

**b.cipolla** · 10-Jan-2011, 21:40

Hello all. I've currently been in the market for a Jobo CPA-2 Unit. I want it to mainly process C-41 4x5 film. I received an offer from someone on this board but I just wanted to check with some people on here about the reported state of the unit. Here's what he had to say:

"He said the original pump burned out and the Jobo replacement was about 500 dollars at the time, so he researched on the net and decided on an aquarium pump, the exit hose for it comes out behind the drum near the lift end and was jury rigged in place with tape. He said this was always adequate for his B&W and that it maintained temperature (72F?, B&W temps anyway, he did not do color)."

This was the only thing that I am a little worried about. Has anyone else heard of using an aquarium pump in place of the stock Jobo pump? Even though he said he would be nice enough to test the unit before shipping it, I want to make sure that this is an acceptable substitute and that it won't crap out or anything. Thanks for your help! What would a fair price for a unit in this condition be? Also, if the person that I talked to about this unit reads this please don't be offended. I just wanted to do my homework.

**Paul Ewins** · 11-Jan-2011, 04:47

An aquarium pump needs to run 24/7 or your fish start objecting whereas a Jobo pump is normally used for only a few hours at a time. The temperature control is separate so the pump should not affect it one way or another. I guess you could calculate the flow rate by seeing how long it takes to fill the drum tempering bath then calculating the volume of that. All you need then is a pump of the required flow rate.

FWIW most of the features of a CPA/CPP unit could be bypassed without affecting the others. My motor control died so now I run the motor directly from an external variable power supply.

**Robert Ley** · 11-Jan-2011, 10:36

I would bet that this setup will work just fine. If it will maintain 72degrees it should be able to maintain 100 degrees. Is the pump external to the CPA-2 or is it built into the unit. That would be the only problem that I would have with that setup. If it was built in it would lower the chance of damage when moving.

**Allen Rumme** · 11-Jan-2011, 10:40

Originally Posted by Paul Ewins

My motor control died so now I run the motor directly from an external variable power supply.

Hey Paul,

I have a processor with the same problem. Could you provide some specific details on your solution. Thanks!

**Paul Ewins** · 11-Jan-2011, 15:56

Allen,
the motor in my CPP is labelled 24v and from memory the internal power supply is 16v so I went for an 18v variable power supply, similar to this one:
http://cgi.ebay.com.au/ATTEN-Adjusta.../270681844069?
and hoped that 2 amps would be enough current. I disconnected the motor from the circuit board (it uses spade terminals, not solder) and then connected it to the power supply by a metre of figure 8 power cable so that I could keep the power supply well away from the water in the processor.

Getting the right speed is a simple matter of changing the voltage. Around 13 volts seems about right for film (i.e. speed F) which is all I use it for. I had done some speed tests a while back before the motor control died so I had a rough idea of the RPM for each setting but ideally I'd like to have them repeated with an assortment of drums with different levels of fluid inside.

You don't have the reversing action any more but as I discovered recently Jobo don't recommend that for film anyway. Using a 3010 drum the current draw was less than half an amp so I could have used a much smaller supply if I wanted.

**Greg Blank** · 11-Jan-2011, 18:17

Wow 500 dollars for a water pump? I can see an installed price of maybe 300-400. I know what I can get them for and what it takes me in time to install them. Unless you know exactly how to put in a non standard substitute you will destroy the processor.

Originally Posted by b.cipolla

Hello all. I've currently been in the market for a Jobo CPA-2 Unit. I want it to mainly process C-41 4x5 film. I received an offer from someone on this board but I just wanted to check with some people on here about the reported state of the unit. Here's what he had to say:

"He said the original pump burned out and the Jobo replacement was about 500 dollars at the time, so he researched on the net and decided on an aquarium pump, the exit hose for it comes out behind the drum near the lift end and was jury rigged in place with tape. He said this was always adequate for his B&W and that it maintained temperature (72F?, B&W temps anyway, he did not do color)."

This was the only thing that I am a little worried about. Has anyone else heard of using an aquarium pump in place of the stock Jobo pump? Even though he said he would be nice enough to test the unit before shipping it, I want to make sure that this is an acceptable substitute and that it won't crap out or anything. Thanks for your help! What would a fair price for a unit in this condition be? Also, if the person that I talked to about this unit reads this please don't be offended. I just wanted to do my homework.

**Allen Rumme** · 11-Jan-2011, 20:32

Paul,

Thank you for the information. My motor is marked 24 volts also, so it is good to know that I don't need a power supply quite that big. I saw that the motor is connected to the circuit board via spade lugs, so that part is a snap. I don't remember right off the top of my head how long the lead wires are on the reversing switch, but I'll probably cut it loose from the circuit board and wire it into the new power control scheme.

Again, thanks for the information.

**Greg Blank** · 12-Jan-2011, 19:11

Originally Posted by Allen Rumme

Paul,
But I'll probably cut it loose from the circuit board and wire it into the new power control scheme.
Again, thanks for the information.

That will be interesting to see, how does your scheme reverse the motor without the existing reversal relay in place? Also how will you insure that the motor will run a consistent speed without the ramping components that exist on the native circuit board?

**domaz** · 12-Jan-2011, 20:43

There should be no reason why a garden pump wouldn't work there. Just keep it out of the heating elements and be careful the cord on the pump doesn't get frayed. Those garden pumps usually have 120 Volt AC cords that are immersed into the water, not the greatest design in my opinion, so be careful.