Rotary switch missing - Gaz4

Open up the GAZ case and if you find the rotary wheel inside, it should snap back into place on its base and allow you to change the setting in the normal fashion. Be careful when making a change of the setting wheel that you don't push down on the dial wheel as that is what causes it to pop off. It isn't very hard to do. Be careful when you remove the digits that you don't damage or unplug the digit ribbon cable or power connector.

There is no way to "fool" the circuit board. The newer GAZ4 units have a piece of aluminum that covers the dial and the entire board is dipped in rubber. We can trade in your circuit board for a newer one if needed. You can hold the rotary dial cover on with careful application of "goop" on the outside of the cover once in place.

Thanks,

It's a Gaz4c I think (about 1990)

Is there a difference in the design?

You have a GAZc

The major differences are:

GAZ4 has a much better battery charging system with more robust circuits.

The rivet holes on the top are better sealed so they don't leak

The main circuit board is dipped in rubber and the rotary dial is secured with aluminum bar.

Both the GAZc and GAZ4 function exactly the same with timers and software

Okay,

I've opened the case and removed the number digits. Found a little black plastic box whith a yellow wheel inside, in the bottom of the
case. But nothing to make contact (like a piece
of metal) for the smalls copper digits, in the black box.
Probably lost.
Will check for a new rotary wheel!
P.S.: very easy to take down.

There should be a contact base on the circuit board in the location where the wheel usually sits. The box and wheel should snap onto this fitment and voila the wheel selection should function again for your timing pleasure.

The contact base (that fit the box) has about
10 little horizontal copper fingers (like wires). If I snap the yellow wheel under those
fingers, how a plastic wheel can control
theses electric contacts? Bizzare!

You are looking for a circuit board that looks like a disk. It has traces that will engage the¨fingers. It is about 15 mm in diameter. It has a key that aligns it into the plastic cover. If needed Mike at Precision can bust open another from an old GAZ board and get you the disk. The rotary dial is the same one as has been used for 20 years.