Type name / number: Hamann 300B
Production / SN: 102 303
Calculating principle: Switching Latch Wheel (UK) ; Schalt Klinke (DL)
Calculating functions: Add, Subtract, Multiply, Divide
Input accuracy 8 / 9 digits
Calculating accuracy: 16 digits
Extra's: Ten key Key-board, Automatic divide and back transfer (value result register to working register).
Designer: Mr. C. Hamann
Production year: 1956 is as date of archive of the Belgian army seen on the plate. According the serial number (102-303) it s production date good be 1954 0r 1955.
(Total production was between between 1954-1959 the corresponding sn from 102001 - 105000, so it was one of the first, production series. )
Case material: Aluminum
Weight: 12,5 Kg
External links:  
Previous owner: J. Vossen, Weert, The Netherlands ( a well known dutch collector of mechanical calculators)
Prior to him the Belgian army was owner, according the plate on the back of the machine and suitcase.
Cosmetic imperfections:
(I accuse no one):
A few paint imperfections caused by usage. The rollers on the bottom backside are to soft to function any more.
Date of receiving: 2012-10-05
Machine story: 2012-10-05
First impression is a good looking and clean machine, out- and inside.
The resistor capacitor and power resistor network, for the spark prevention on the switched and the motor speed regulator switch are completely removed and not restored again, so some sparking was seen during first operation and ozone like smell was prominent. (That's not my preferred restoration method). I will add all those components again with the current versions, who will protect the electrical interrupters and prevent them from burning in.
First calculation (adding) check was ok and showed a very silent machine!

2012-10-06
Divide check passed. The digit indicator which is missing on the first machine is functioning on this one. Electrical earth connection to the bottom and side plate is not connected, wiring left open. Will be repaired as well, without any doubt.
An unknown spring is localize on the back of the machine, motor screw to an bigger spring. (See later at 2012-10-16 is is due to the friction in pinblock transport)

2012-10-07
Removed the motor to see more in detail the situation on the removed components. Indeed heavy sparking was examined on the speed regulator switch. Now due to the missing power resistor, the speed regulator is switching the motor on off, in stead of on and via the 1.2 KOhm power resistor. So the speed is lower by the same screw setting. I dismantled the contacts to inspect the burning. The surfaces where black / corrode. In are probably silver plated so a little surface cleaning is only needed to have as large as possible contact area.
Between my spare parts I found an exact copy of the power resistor (1.2KOhm 50W) at an spare Hamann E. Most others machines have resister values of 800 and even 100 Ohm.

2012-10-08
Have assembled the new components on the motor (for protecting the speed regulator switch). In this case I have complete and leave the RFI part as well, for the nice looking.(Please see the pictures)
Now I have to find or make a housing which looks like the large oval box containing the network for the on of switch protectors.

2012-10-09
The intermediate housing for the switch protection is added. Function test is passed. In the dark only noticeable little sparks. Photo's added to site.

2012-10-15
I made a wooden case which looks like the original pertinax case at the machine back side. Here is the capacitor and resistor combination for the switch protection housed. Have to see if the pertinax folly even looks better when I fowled that around it. The bottom plate is on the next pictures. On the photo's the original inner capacitor of the first 300B is showed as well to compare both sizes and modern and old inner components.


2012-10-16
A metal strip bended to hold the new wooden unit.
Cleaned the whole machine in and outside to remove the old oil smell. Mount the new wooden protection unit. Make pictures of the complete machine, including the new installed components.

Calculation check shows that the pinblock is stopped at the 5e inputted figure. Now it is clear that the previous owner has mounted the spring to the larger spring!!!! Have to see what the reason of friction is!
The left carriage transport key is some times not possible to operate. Have to see what holds it from doing so.

 

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