This is a 1960s Junghans ATO-MAT S clock that uses a transistor circuit to keep the oscillation of its balance wheel running (identical principle as in the Benrus Electronic Citation - just in bigger).
For its time a modern design with good quality components - it can still work today.
The "slide-in" clock module and dial.
Hands taken off.
The movement removed from the dial. On the left is a hack lever to stop the movement of the balance wheel and thus of the movement itself (this is not an OFF switch as the circuit will still consume battery power).
The Junghans W707 in-house movement.
No mainspring anywhere - all the power comes from the battery.
The electronic module is held in place by a single screw.
The huge balance wheel with two magnets and two counter-weights.
Teardown of the escapement mechanism.
A side view of the wheel train. As all the "drive" comes from the balance wheel, good lubrication is essential for good timekeeping here.
Another view of the wheel train.
The escape wheel engages directly with the balance wheel - a simple construction with a minimal number of parts.
The parts before reassembly.
Cleaned wheels - somewhat too much oil here...sorry.
The movement back in action.
Done and keeping time.