K & O armature coil

[Bob Reichel]

I'm no stranger to clock repair, so my son brings me a Kieninger & Obergfell swinging armature clock to "fix" ! Talking to some of my compatriots elicites the comment that "the coil 'may' need replacing". They also thought that Merritts had the coils for sale. I don't have an answer from Merritts on my question as yet-but what are the thoughts on my problem.

 

[eskmill]

The KundO electronic clocks are of two kinds.

One with the transistor(s) underneath on a small printed circuit board. An electronics "guru" should be able to determine if the coil or the components on the printed circuit board is/are bad. The transistors are generic on the circuit board.

The other kind has a single transistor buried in the bobbin of the sense/drive coil. The exact transistor hasn't been available for years and substitutions are too big to fit into the space in the bobbin. Worse, one would likely destroy the brass bobbin/coil housing trying to open it to get at the coil and transistor.

Some have found the coil winding open especially the model with the buried transistor because there's two coils; one sense and one to drive the pendulum armature. The wire is extremely fine and I believe the wire breaks due to changes in temperature and manufacturing stress. The working current is too small to burn the coil.(s)

Personally, I've never had any kind of luck except with the model having the printed circuit board although I have several of the other style with the buried transistor that still operate.

Best bet is to keep an eye out for a salvagable donor and hope it ain't broke too.

 

[Bob Reichel]

Thanks for the reply. I understand what you are saying. I was able to search on and found the submitter that had the 6 pages of
German "repair instructions'. I copied it and also looked on eBay and found there are similiar units for around $20.00. That sounds better than the suggested $40.00 for a new coil. (if they are really available).

 

[Bob Reichel]

Opened up the can as I have an electronics geek coming to check it out. What I see is a yellow plastic spool with the coil (s), a black transistor tucked into a hole in the plastic spool. On the other side from the trans is a 'resister' looking thing. Visual examination does not reveal any broken wires-but whats under some of the silver epoxy may be another thing.

 

[Mike Phelan]

Bob
Open-circuit coils like this, with very fine wire, may not be visibly broken; it's usually green-spot corrosion that sees them off.

Anyone who repairs more than one electric clock a year needs a cheap meter - over here they are about £3.

Not only use it for clocks - cars, washers, fridges, radios - the list is endless ....