Need help with JOBO

Got an old CPE-2 with Lift last week. It seems to be doing great job
keeping chemicals @38C degrees as meassured in a bottle. However, when
I measured temperature in a 1520 tank the temp dropped to 36.4C after
7 minutes of processing.

The tank was preheated by rotating it dry for 5 minutes, per JOBO
manual. The water level in the bath was high enough to cover about 1/2
inch of the 1520 tank. The unit is leveled. I used water instead of
chemicals. The water came from a jobo bottle tempered in the bath and
it was exactly 38C degres. I poured about 300 ml into the lift's
funnel and continued to "process" it for 7 minutes. To meassure the
temperature in the tank, I stopped the machine, openned tank's lid,
and meassured it there.

Is such a high drop in temperature (1.6C of 3F) normal?

Regards,
alex

alex wrote about his CPE-2 and its
temperature regulation:

(snip...)

Is such a high drop in temperature (1.6C of 3F) normal?

Yes. The drum is wet as it rotates, water evaporates off
the drum, and the temperature falls.

After a bit of experimentation when I first got it I now
set my CPE-2 to 2 degrees above the desired temperature.
For C-41 processing, for example, I set it to 40 degrees.

Laura Halliday VE7LDH "Que les nuages soient notre
Grid: CN89mg pied a terre..."
ICBM: 49 16.05 N 122 56.92 W - Hospital/Shafte

wrote:

Got an old CPE-2 with Lift last week. It seems to be doing great job
keeping chemicals @38C degrees as meassured in a bottle. However, when
I measured temperature in a 1520 tank the temp dropped to 36.4C after
7 minutes of processing.

The tank was preheated by rotating it dry for 5 minutes, per JOBO
manual. The water level in the bath was high enough to cover about 1/2
inch of the 1520 tank. The unit is leveled. I used water instead of
chemicals. The water came from a jobo bottle tempered in the bath and
it was exactly 38C degres. I poured about 300 ml into the lift's
funnel and continued to "process" it for 7 minutes. To meassure the
temperature in the tank, I stopped the machine, openned tank's lid,
and meassured it there.

Is such a high drop in temperature (1.6C of 3F) normal?


Should make no difference, and I've never heard
of anyone taking the drum temp. as opposed to
the solution temp. Consistency is what matters.

Jobo, Kodak, etc. base temp recommendations on
water bath/solution temp, not drum sol. temp.
38 C indicates you're processing color (E6/C41.)
A couple of degrees +/- isn't as important to the
process as temp. consistency.

If you're that concerned with variations due to
processing I'd suggest you run control strips
as this allows fine tuning of the process given
the Jobo's excellent temp consistency.

I switched to expert drums (3000 series) just to get away from the
problem you are talking about. It's real.

Here's a trick a friend showed me (after I spent several hundred bucks
on new drums).
She got an aquarium pump and pumped a little stream of water from the
bath over the top of the rotating drum. This is just enough to deep
the temp drop from getting too large. (There will still be a little
drop, but not 3 degrees F.)

What a cool trick! The other option would be to point a halogen lamp at
the tank, but it has issues.

Thanks!
alex