Change RCP20 for RA-4 process
by Eduard Giessegi
(from: Foto hobby labor 4/1990)
If RA-4 comes RCP20 have to go! One could have this fear at least, after
first nothing and then only a halfhearted reequipping supply of DURST came
as solution. Now fearing for has an end: In this contribution we tell you,
how you can process the RCP20 on a development time of 45 seconds trims
and RA-4-Material perfectly.
While laboranten with drum processors can drive almost any process,
the owners of (not modular) machines always encounter in the case of a
process conversion larger and partly also not problems which can be solved.
Because one knows a machine, which is conceived for a certain process,
not or not optimally for other processes normally uses - that is evenly
the price for the otherwise faster and more comfortable processing.
A special position has here the RCP20 of DURST: It is optimized not
on that so far as standard valid EP-2-Prozess, with which the bath times
for developers and bleaching fixing bath differ clearly, but operates with
same bath times. This circumstance proves with the processing of EP-2 naturally
as disadvantage, since one does not come on those shortest possible total
turn-around time. Before the background of the world-wide conversion to
the RA4-Prozess looks however differently, because with this process developers
and bleaching fixing bath have the same bath times.
Quite so, as the thing thereby seems, it is however not rosy: The RCP20
offers same bath times, but these are much to for a long time. One concretely
comes on a development and a bleaching fixing time of 140 to 145 seconds,
needs becomes however in each case only 45 seconds. Now naturally the thought
is situated near to increase easily the drive rate of the machine and to
thus shorten the turn-around time. But more with difficulty than one shows
oneself first mine could.
In snail speed to high rate
For the modification of the turn-around time one needs to adjust the
automatic controller for the drive rate in the simplest case
only. Such an automatic controller those does not offer to RCP20 however,
so that with this machine, from the manufacturer
firmly given turn-around time is only available. In order to change
the drive rate, one must intervene thus in the interior life of the machine.
In addition, that is more easily said than done, and who threw already
once a view in the inside of its RCP20, it knows that one with any simple
cheat to nothing align can.
Without something professional is of an acceleration of the RCP20 therefore
not to think - and since those came already end of
passed yearly effected announcement of DURST even quite, after which
it meant that one wants to be able to be broken in for the re-equipment
"somewhat". Unfortunately from it however no small bag with gear wheels
became and get it for nine and thirty eighty or similarly reequipped, but
only one service supply: Who sends its RCP 20 to DURST, it - for approximately
150 DM - gets after two weeks faster and also generally checkt back.
As far as so good, but the dream of the super+short turn-around time
lasted not for a long time. Because as one soon determined, leaves themselves
developer- and bleaching fixing time of 140 to 145 seconds "for constructional
reasons" only to 120 seconds reduce, which more briefly, but than those
shortest possible time is still clearly longer. Thus not enough: Pointed
to newest information DURST will not receive this service supply upright
- "continuous tests to have that such reequipped machines cannot fulfill
our high claim of quality", such a speaker of DURST.
Thus we are today again in the same place as scarcely one year ago,
when the RA4 came to the hobby laboratory, and owners of RCP20 it asked
rightfully whether this confusion was really necessary, whether one cannot
count as buyers of a label device of a renowned manufacturer on a better,
adequaten service and whether the technical reasons are flanked not also
by economic interests - finally also Printo and ACP200 want to be brought
still to the man...
However: After long time we can offer here at least all a solution
of the problem to those, which have a fate little relating to
crafts. Found from Eduard Giessegi, teacher for art education and photography
at the High School in Forchheim. "The idea to the change came me in connection
with a bargain", says the 42year old paedagogue and completes: "there I
still rather black-and-white photograph and also in the school laboratory SW than
the higher art publicise, tried I, to accelerate the
monotonous and unkreative color processing - only thus succeeds manufacturing
in the lessons also color pictures in an acceptable time so that the pupils
can worry about the picture design"
Highspeed RCP 20 - with 50 DM participate you
In order to accelerate the RCP20 really reasonably, one have to modify
the mechanics radically. This by two new gear wheels become possible and
a toothed belt, if the machine is equipped with such not already. All parts
one get it for example from Conrad electronics for scarcely 50 DM. It is
possible to convert the reduction ratio of the past drive into a speed
ratio from 1:3. The machine achieves then a rate, which leads to a development
and a bleaching fixing time of approximately 45 seconds.
The thing has a hook however: Depending upon tool kit you must possibly
fall back to the assistance of a precision mechanic.
Concrete the propelled axle is to be turned off, so that one can install
the small gear wheel to drill out and the large gear wheel so that it fits
on the propelling axle. Before putting the large gear wheel on the propelling
axle one must make then still the directly lying beside exhaust wheel on
the engine axle somewhat smaller, so that the two do not come themselves
into the traverse. But a side cutter is sufficient, with whom one cut simply
the wings of the ventilator. After are concluded this pre-working, one
can put and with the clamping screws lock the gear wheels on the axles.
In the end the toothed belt is used and strained. The run and the tension
of belt are to be adjusted in such a way that the axle does not strike
and the machine runs approximately (to stretching the toothed belt one
loosens the screws at the disk, on the engine and transmission is installed,
shifts her accordingly and tightens the screws again).
The new drive mechanics and the cuted exhaust wheel.
Essential: A velocity test
If one proceeds from the ideal velocity standard RCP20 (140 to 145
seconds of development and bleaching fixing time),
there are after the change in the case of use of the gear wheels mentioned
purely computationally 46 to 47 seconds of
development and bleaching fixing time. This corresponds rather exactly
the RA-4 process time (45 seconds per bath), but this
value is not always achieved. The cause for deviations is situated
in the dispersion with the production series to never exclude completely
leaves itself. In the case of the RCP20 converted here a development and
a bleaching fixing time of 40 seconds resulted after the change. Such differences
are however no problem - one can adjust you by an adjustment of the temperature.
With the Diluprint-4 used here for the practice attempts the best results
are at a temperature from 25 to 26 degrees.
Note: If you likewise use this processing record, but still over the
older Dilublix bleaching fixing bath, must you order it 1+3 instead of
1+4 set. Who converts its RCP20 in the way described before, the real new
rate should determine thus in each case and adapt the temperatures.
In order to determine, on which development and bleaching fixing time
one comes, one a piece puts photo paper into the
current - and with liquid filled! - machine and measures the time of
entering the paper by the rollers of the developer rack up to
entering the paper by the roll of the rack; for this time the optimal
temperature adjustment one infers afterwards from the chemical description
Do it yourself
To the termination you should know still following: In the way described
before the converted RCP20 was extensively tested. The test runs extended
over a half year, whereby several hundreds paper were processed. All results
were perfect and constant; Irregularities did not occur. Nevertheless it
must be pointed out that with a change after this guidance no guarantee
for a perfect function and error free results can be taken over; beyond
that it is to be considered that a possibly still valid manufacturer warranty
goes out by this intervention. Particularly importantly these notes appear
to us, after DURST does not offer re-equipment on according to short times
and this with continuous tests justified, which showed that such reequipped
machines do not fulfill the high claim of quality of DURST. We can
it this not reconstruct, may in addition, not for all machines ever built
Data of the RCP20 for RA-4
| Paper ||
|| Input time ||
|| page/hour ||
|| use ||
|| capacity |
| 13x18cm || 25 sec
|| 144 St. || 800 ml ||
|| 450 Bl. |
| 20x25cm || 45 sec
|| 80 St. || 800 ml
|| 250 Bl. |
The (really tested) table codes refer to 2,5 litres of work solution
of the Diluprint-4-working bathes on utilization of the chemicals without
A large gear wheel with 30 teeth and a diameter of 54 mm. Catalog part number: 226041-44; Price: 11,95 €.
A small gear wheel with 10 teeth and a diameter of 24 mm. Catalog part number: 226106-44; Price: 6,95 €.
A toothed belt with 65 teeth and an effect length of 330 mm (ZAHNRIEMEN 65 Z), if the drive
operates so far with a drive belt. Catalog part number: 226076-44; Price: 2,75 €.
Note: The part numbers and prices apply to the purchase from
, as one from different possible sources of supply. Status: 2004
Scanned from: Foto Hobby Labor 4/90
Author: Eduard Giessegi/RG
Also I successfully converted my RCP20 after this guidance. It pay attention
that the gear wheels of the racks before inserting
into the filled continuous processor in waterbath are made usual, in
order not to load the engine after the new translation by
caked-on axles still additionally!
I use the process: Mono PK RA-4 von Tetenal, for 2,5 litres of color
developers and 2,5 litres bleaching fixing bath (costs 1999
approx. 48.-DM, Saturn-Hansa Frankfurt/Main). I set and always increase the
developer temperature at first to 26 degrees of C by 1 degree after throughout
of 10.000 qcm photo paper. Thus:
to 10,000 qcm 26 °C
to 20,000 qcm 27 °C
to 30,000 qcm 28 °C
to 40,000 qcm 29 °C
to 50,000 qcm 30 °C
For the temperature measurement I take a digital thermometer (with
cable for outside temperature, to buy in the shops for
approx 10 €), since the inserted automatic controller measures too inaccurately.
Translated with help from Alta Vista!
Stefan Wehr, 15.10.2004