previous <<==>> next

CONTEX  -  55

TECHNICAL  DATA  of  the  Electro-Mechanical  Calculator          CONTEX-55

Serial Number:       493088787

Dimensions:   (ca.)  Width   =   8    " /  20 cm
                     Depth   =  11_1/4" /  29 cm
                     Height  =   4_3/4" /  12 cm

Weight:       (ca.)  9_1/4 lbs  /  4.2 kg

Power Supply:        220 V AC / 45 W

Mechanics:           10-Block-Keyboard,
                     Serial-to-parallel Conversion
                     Rocking Segment Mechanism

Functions:           Add, Subtract, Multiply, Divide

Registers:           Input          =   10 Decimals
                     Arithmetic II  =   10 Decimals ( Division )
                     Arithmetic I   =   11 Decimals ( + | - | * )

                     BRDR. CARLSEN
                     Gentofte, Denmark

H O W   T O   U S E   the  CONTEX - 55
A condensed instruction from the CONTEX-55 back side ...

FULL INSTRUCTION (in Engl., German, French & Danish) available from ...

R E M A R K S :
Two lines of interesting and innovative mechanical calculators came on the
market under the name  » CONTEX «  in the '50s and '60s :

The first was a key-driven adding machine in style of a Comptometer, with
a "half" keyboard and simplified mechanism:  CONTEX-A  &  CONTEX-B.

The second was a series of 10-Block-Keyboard machines.  The  CONTEX-10  is
a manual one.  The CONTEX-20 is motor-driven.  The CONTEX-30 has improved
motor-driven multiplication and division.  This  CONTEX-55  has its own
DIVISION REGISTER  to show & complete the division full automatically.

R E M A R K S   T O   R E S T O R A T I O N   O F   T H E   C O N T E X - 55
The left top blue button was missing. Goal was to make 2 fixable buttons ...

... One part out of a cable connector ( = "Luester-Klemme" )  was split and
both pieces soldered on brass plates of 8 mm diameter.  Smaller headless M3
Screws are used.  Insulation distance pieces from connectors make the  BLUE
& RED  caps.  Colored insulation tapes cover its top holes ...


... The "ON-BOARD" SOLUTION!                  ... and the left ORIGINAL ONE

S T A T U S :    Addition  &  Subtraction  =  ok
-------------    Multiplication  =  ok
                 DIVISION  "sometimes"  ok ...

To find the DIVISION ERROR, a CRANK FOR MANUAL OPERATION had to be made ...


... The motor-axle got extended with a glued-in  M4-HEX-POST  to solve the
"Engineering Problem":  CRANKING had to be COUNTER-CLOCKWISE!

R E S U L T :    Division  =  OK  IN MANUAL MODE - ! - In AUTO MODE:
-------------    Random MATRIX-TONGUES were moving in & out caused by
                 the vibration of the running motor ...

The calculator had to be disassembled until the Matrix-Unit was in hand.
As "1st Aid" the unit was dived in alcohol: Tongues moved back & forth to
remove all oil residues in hope that better friction will do the job ...
YES! That was it! Now the CONTEX-55 works well again!

W A R N I N G :  Take your time and be patient: It is really difficult!
Make extensive notes & pictures when disassembling this heap of levers,
springs & screws - You need 5 hands to bring the parts in place again ...

The state of the CONTEX-55 in the picture shows the result  22/7 = 3.14 ...

© C.HAMANN        09/25/10