Hamann 300

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

Repair Info

When I received it, this calculator was in a reasonably nice condition. It could add en subtract, but the carrier transport didn’t work properly and division didn’t work at all.   With this Hamann I learned that removing the carriage is very easy ..........  if the machine works properly.  If it doesn’t, removing it can be a tough job.  However it is necessary to reach some parts that may obstruct it from working properly.

Carriage removal:

With the machine in its normal position on the right-bottom of the carriage there is a small peace of steel attached with two screws (see photo  A). Once that has been removed, the carriage should come out easily. To remove it move the carriage to the far right.  After removal the carriage can be moved to the left until it comes free and can be taken out.  It’s best to operate the carriage by hand using the small wheel which is driven by a long steel spring. At the same time push the right-tab key respectively the left-tab key. Using motor power is also fine if the machine functions well.

If the carriage seems to be blocked, there is one thing to check:

Did the main register (Reg I) finish its 360 degree turn? If not than the carriage is firmly hold by two mechanisms. One is visible on the photo “C”  at the yellow arrow.  The other is underneath the carriage and only visible after the carriage has been removed.

A common reason for reg I not reaching it’s 0-position (photo D), is  a difficult turning counter wheel (Reg II). It’s probably visible by a counter wheel  being half-way a movement to the next digit position (photo B). In that case use some WD40 and try to loosen that counter wheel with your fingers.

If for any reason the main rotor should be turned, you’ll need a special tool that fits the main shaft.

Spark suppression:

Many, perhaps most machines suffer from leaking or removed capacitors.  In this machine they were removed. That’s not OK for those parts that take care of contact spark suppression. I tried to recover the original suppression circuitry.

If a leaking capacitor is “on power” constantly it will slowly heat up, leak a bit more, become heater and finally explode.  If it does it may spread a lot of  sticky, hard to remove dirt inside the machine.

P1000354a.jpg P1000353a.jpg P1000355a.jpg P1000356a.jpg P1000357a.jpg P1000358a.jpg P1000350a.jpg CIMG2339-position-lock-s.jpg P1000130s-cntr.jpg P1000106a.jpg

A: Carriage end stop

C: Carriage fixation while      adding/subtracting

B: Counter half-way

D: Rotation 0-point

Motor speed control:

When the motor is removed from the main frame, the cover (E)  from the speed control becomes visible. The ribbed black screw is used to adjust the speed.  After taking of the cover the outside of the contacts (F) becomes visible.  Picture G shows the centrifugal mechanism.  H shows the hole which gives access to the speed control screw.  It was about 220 rpm.  Turning it to the right raises the speed.  During maintenance I’ve set it to about 270 (not 350 to reduce mechanical stress).  In the video it is 220 rpm.

P1000063as.jpg P1000069as.jpg P1000139-stk-arrow-s.jpg P1000073as.jpg

F: Contacts outside

G: Centrifugal mechanism

E: Cover

H: Speed control