Brunsviga 16E

Calculators I added to my collection seldom worked when I got them.  This calculators wasn’t any different in that respect.  It came in blocked.  I never use the motor until I’ve build some confidence that a calculator will work as expected.  

So, I used a screwdriver to move the motor on the speed regulator side.  While I didn’t use much force I noted  that several parts of the machine were bending.  Maybe it’s deliberately build that way, but it doesn’t feel well.  While working to get it operational I also experienced that it is easily brought into modes from which it is very hard to return to neutral. I  learned to be very careful touching controls while handling the machine.


Apart from the more or less usual problems mostly caused by dried oil and fat the following repair actions were performed:

  1. On the Reg-III shaft there is a coupling which is intended to  create some flexibility between this shaft and the motor + gearbox.
    I guess that the manufacturer used a rubber part to create the flexibility, that it has deteriorated and was ever replaced by a piece of hard plastic. I restored the flexibility that I assumed and got rid of all blocks during motor operation.
    (Click the picture below for a pdf  with a more detailed description)
  2. Digit input, in particular of digits 1, 2 and 3 often led to an input block.  Using a high speed video I noticed  that there was quite some bouncing in the toothed arm which enters the digits in Reg-III.  A bounce damper cured this problem.
    (Click the picture below for a pdf  with a more detailed description)
  3. In the electric module on the back of the machine two components were not connected to the relays.  I got the impression that they were never properly soldered and came loose (maybe after years) due to vibrations.  I had to partly disassemble the module to solder these parts back in place.


The use of solenoids may give the impression of making the machine much more complex than purely mechanical machines.  In order to understand the machine including the role of the solenoids I reverse engineered the electric parts.  I discovered that the solenoids are only used for rather “safe” actions: Disable of input during operations, digit input and  register resets.


If needed electric diagrams can be downloaded from the assets page of this site.  


Click to view a full size picture (opens in a new tab)

Repair Info Front-Stacked-S.jpg P1000778aS.jpg P1000920aS.jpg P1000924aS.jpg P1000922aS.jpg Bounce Damper.pdf Flexible Wheel.pdf

Flexible joint

(Click picture to download a description)

Bounce damper

(Click picture to download a description
Click the camera icon for a slow motion video)

Control Bars.pdf

Control bars

(Click picture to download a description)

Assets: adverts, brochures, etc Video