Jobo CPP-2 temperature display question

Dave Starr said:

Another Jobo newbie question...... Does it noremally take a while for the temperature display to settle down? On mine, bought used, it can take up to an hour before the display stops jumping all over the place. Once it settles down, it's fine. Just wondering.

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I've had a CPP-2 and currently have an ATL-2300 and neither display jumped around. Perhaps you could give us a more detailed desription of "jumping all over the place". Does it read random numbers or does it slowly ramp up to the set temperature over the course of the hour? It should be the latter, not the former.

Another Jobo newbie question...... Does it noremally take a while for the temperature display to settle down? On mine, bought used, it can take up to an hour before the display stops jumping all over the place. Once it settles down, it's fine. Just wondering.

I fill my Jobo with water at about 30 deg C an hour before processing, and then turn it on. The digital display shows about 28 deg C and smoothly ramps up to the proper temp over about 1 hour. I have it set at 38.7 deg C.

I don't have the cold water option attached.

There is no jumping.

Is your pump operating? Could there be a loose or corroded connection? You can remove the entire control unit and inspect the underside rather easily by removing the large screws on the front and back.

Make sure it is unplugged if you do.

PE

Dave Starr said:

Another Jobo newbie question...... Does it noremally take a while for the temperature display to settle down? On mine, bought used, it can take up to an hour before the display stops jumping all over the place. Once it settles down, it's fine. Just wondering.

Click to expand...

Can't speak for the CPP-2 but I have a CPE-2 and the thermostat light is strangely on and off frequently even when the Jobo thermometer is still reading below the required temp. You'd think the light would be on all the time. Once it gets there it behaves the way you'd expect and maintains the temp at a rock steady reading. I find that the thermostat knob is pretty accurate but is calibrated marginally on the low side compared to what the thermometer shows e.g. I set the knob at just over 35 degrees C to get 35 on the thermometer.

I think this must be normal because in his book about rotary processing John Tinsley mentions having a time switch to turn on the Jobo about an hour and a half before starting processing. Fine if you work say 9-5 but a drag if you want to do a little printing in the evening.

I usually try and fill with water at about 1 degree within processing temp to speed things up and place the dev and blix into containers at say 45 degrees C or even a little more and put another thermometer into each. Even at room temp the dev and blix will rise quickly. Just move them to the Jobo when say 34 degrees are reached.

Pentaxuser

I have the CPE-2 and the thermostat works fine. In the begining he works harder to reach the tempereture requested but as it is coming closer to the tempereture it slows down.

langedp said:

I've had a CPP-2 and currently have an ATL-2300 and neither display jumped around. Perhaps you could give us a more detailed desription of "jumping all over the place". Does it read random numbers or does it slowly ramp up to the set temperature over the course of the hour? It should be the latter, not the former.

Click to expand...

It's reading random numbers.
I opened it up - I used to do electronics repair - and carefully unplugged and reconnected every wire connection. I found a severely pinched wire from the pump housing to the top switch board - temp probe, I think - & clipped out the bad section & soldered the ends together. No luck. All solder joints look good. I pulled the bottom - transformer - board & looked at it. It's been repaired more than once. In some spots the foil on the board had been bridged with wire. Without a schematic, there's no way of knowing where the problem is. What really bugs me is that it worked great for 1 1/5 months. Now that I'm hooked on using a Jobo, I guess I'll have to look for another one. Judging by the prices from 2004 on their web page, that would be cheaper than replacing the boards in this one.

DANG

Sorry to hear that. I have an electonics background myself. If it works fine when it heats up, you may have a loose joint or connector that makes contact after some thermal expansion. Worth a try...

langedp said:

Sorry to hear that. I have an electonics background myself. If it works fine when it heats up, you may have a loose joint or connector that makes contact after some thermal expansion. Worth a try...

Click to expand...

Or a loose connection that is bridged by condensed moisture when the unit gets hot enough, or a bit of corrosion on a contact that is bridged by moisture, or an IC that works better when it heats up, etc.

I hope you find it. It is a fine unit when working properly. Best of luck to you.

PE

I had something similar with my CPP-2... but the temperature display jumped all over the place - never settling down. That was caused by water migrating into the control unit, capillarying (sp?)up near the pump shaft. I would make a guess that, for some reason, water was getting into the control unit ... probably through condensation, and drying out after a period of time at an elevated temperature.

I would suggest using a silicon waterproofing compound ... apply it to any possible paths of water migration.

SOLVED!!!! I checked on the price of replacing the circuit boards & such, which was beyond outrageous. The temperature display board is now over $300.00! I really didn't want to take a chance on another used unit, so I started calling and found a new CPP-2 and lift at Freestyle. I really hated to spend that much, but it was either that or go back to trays and tanks. Using the Jobo for a month made that a no-brainer. The new one WILL be sealed before I use it.

I had the same problem with a cpp, the problem was fixed with a new temperature sensor probe. You can try and substitute a fixed resistor for the probe and see if the display settles down.