Repair Info

Mechanical calculators and typewriters

Electronic calculators

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Several collectors (*) helped a lot to develop the skills which enabled me to get every machine on this website in a working condition.

(*) Note: many of them present on the internet:  see Links


The very basic necessities:

A headlight and small led light help to see what’s happening inside a machine.




Petrol mixed with a few percent of thin oil  and some small brushes help to clean the machine.

WD40 helps to loosen stuck parts.

  

For most lubrication a reasonably thin oil is OK.
I use 15W40 motor oil for most parts.


For very small parts clock oil (Koch nr 3 or 4) seems to be fine.


For gears a multi-purpose grease is used.

Some small wrenches are used a lot: 5/16”, ¼” and 5.5mm.  Others may well be needed.

Some screwdrivers needed modification to accommodate the sometimes very narrow screw slots.

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The electrical part looks  like this diagram.

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The electronic calculators I bought general need no repair except for replacement of rechargeable NiCad cells.
If the cells or normal batteries have been leaking,  the contacts can be cleaned with vinegar.  That generally gives satisfying results.  


NiCad cells can be replaced with modern low-leakage NiMH cells. They will have a much larger capacity resulting in much longer charging times than originally.  Take that time and don’t alter the charging circuit unless you know what you’re doing.