Revision of a Caliber Junghans 620.56; Diehl 620.56

Diehl compact with water damage


Junghans 620.56; Diehl 620.56; Front


Junghans 620.56; Diehl 620.56; movement

Rust is an iron oxide, usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture.

That´s how the Wikipedia article on rust starts.

This watch was certainly in contact with water through the crown. The fund state made ​​me doubt whether this watch would ever ticking again or whether it should migrate to the movements, which should serve as a replacement for future revisions.

But try is making wise and so the movement was first dismantled so as to examine more closely.

The winding stem is beyond saving...


Junghans 620.56; movement dial side


Junghans 620.56; movement


Junghans 620.56; broken ratchet wheel


Junghans 620.02; board

The winding stem  was already out of the movement and when pulling the crown the stem met me completely. When I took of the hands and the dial it hit me hard. The entire winding staff around the clutch wheel and the winding pinion was one rust lumps.

When removing the cover plate has been clear that the ratchet wheel had lost two teeth. In my stash I had an incomplete movement of a caliber Junghans 620.02. This was declared as a stock of spare parts.

The fight with the rust


Junghans 620.56; barrel with rubin


Junghans 620.56; barrel with rubin


Junghans 620.56; ratchet fixation


Junghans 620.56; ratchet fixation


Junghans 620.56; stacking tool

The Junghans 620 has an easily removable barrel. This version is specially mounted with two rubies and the upper bearing is easily removed by a small bridge.

Unfortunately it was not as easy as I hoped. When removing, the Rubin remained stuck on the rusted axis of the barrel and could be disassembled only by soaking the barrel axis in oil. There was a whole night in oil...

The cover of the ratchet was pinned in the deck board. In the attempt to remove this the next mishap happened: I tried to pull the plate from below where it broke me. It is better to drive it with the staking tool from above, which I did then (of course inevitably then also with spare parts).

Fixing of the ruby ​​of the mainspring barrel bearing


Junghans 620.56; stacking tool

The staking came again to use: The rubin of the barrel  bearing had to be back in place. It was the first time that I put a ruby ​​in his metal bearing and I can anticipate: The bearing did his work .

The cleaning


Junghans 620.56; disassembling


Junghans 620.56; parts


Junghans 620.56; parts


Junghans 620.56; parts

Usually I clean the surface of the removed parts with a small brush or Rodico and then in the watch cleaning machine. This nevertheless clearly rusty movement I decided it to be cleaned even in an ultrasonic bath.

Then the rusted parts were processed with a fiberglass brush and as far as I can polished.

Some parts were so attacked by rust that I was exchanging them.





Junghans 620.56; assembling


Junghans 620.56; assembling


Junghans 620.56; assembling

The board and some parts were ground free up to the support material.

The winding stem was replaced and was to long, so it has to be shortened.

The dial - plastic


Junghans 620.56; dial


Junghans 620.56; dial


Junghans 620.56; dial


Junghans 620.56; dial


Junghans 620.56; dial

The dial of this Diehl watch is made of plastic and has a solar structure. The luminous material is thick and exalted applied to the figures. Unfortunately, this was distributed over a few places in the grooves of the structure of the dial. There I took this off carefully and cleaned the dial easily. The luminous material at least contains radiation tritium or even radium, so it is advisable to work always well protected, that is with mask, goggles and gloves.




Junghans 620.56; Front


Junghans 620.56; movement


Junghans 620.56; Front


Junghans 620.56; movement


Junghans 620.56; back

Only cut the winding stem and the watch was already done! A hard but nice piece of work...