Jobo CPP2 temperature knob "locked"

Discussion in 'Darkroom Equipment' started by Kino, May 29, 2006.

  1. Kino

    Kino Member

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    I have a Jobo CPE2 Plus drum processor with lift that has the temperature control locked at 99 F; at least, that is where my thermometer indicates the tempering bath stabilizes.

    Now, I have had this unit for several years, got it in an auction but never have used it, and don't remember if this was the way it has always been, but am suspecting it was adjustable in the past.

    Anyone ever heard of locking the thermostat on a CPP2? Would 99-100 degrees F make sense? Can you lock and unlock the unit?

    I just recently washed the unit when I my darkroom was finished about 6 months ago; any chance it has rusted in place?

    Confused...
     
  2. markbb

    markbb Member

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    Having just taken a CPA2 apart, I suggest you do the same. The heater knob is connected to a simple variable resistor, so you could check to see if it's got gummed up. Failing that, it could be that theres some-thing up with the thermostat, have a quick look to make sure all connections etc are clean. Go here for instructions: http://www.jobo.com/jobo_service/us_analog/index.html

    By the way, 100F is the temperature for E 6 processing .
     
  3. davetravis

    davetravis Member

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    Kino,
    When I use my CPP2, I run 4 full bottles of hot water through the lift and into a "waste drum" to remove residual chems, and fumes. But no, I've never had the temp control lock up. Maybe some drip-less oil on the resistor if you disassemble it? Just a thought.
    Good luck.
     
  4. Kino

    Kino Member

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    Thanks Markbb and Davetravis!

    I will disassemble the resistor and have a look; never had one apart, so I was looking for a "don't touch that" or "its ok" post!

    Could be that the prior owner had some trouble and locked the resistor down to E6 temperature; I know variable resistors can cause troubles.

    Again, thank you.
     
  5. Ed Sukach

    Ed Sukach Member

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    I'll make a wild guess that someone deliberately modified that processor by adding some sort of locking mechanism (set screw?) to that adjustment shaft to keep the temperature to 38C - the temperature for C-41 and E-6 developing.

    I've disassembled that Control Unit myself a number of times .. not the easiest thing in the entire world... but with care ...

    Hey ... a thought. Pull off the temperature control knob and see if anything looks "modified."
     
  6. Kino

    Kino Member

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    I will do that tonight.