Tiny little compression spring working against watch back and rear of face

[keysinthecity]

So yesterday we had a watch battery in to change and there was a tiny little compression spring with a slightly wider footprint (think sort of trumpet shaped) which sprang out when I undid the screws and took the back off.

 

I could see that the previous person to change the battery had just sort of bunged it in, but actually the plastic bezel had an aperture to retain the spring. It was a massive faff to get it back in the hole without losing it but once in and the plastic bezel returned to the case, it was reasonably secure.

 

My question is, what is the purpose of these springs? The watch worked with or without it.

 

I've seen some other watches have a bit of raised metal to make contact against the watch back and they also seem to work without this in contact with anything.

 

Still others (God, last one, promise) say: "to reset after a battery change short this contact against this contact" - but I've never had to do this yet.

 

So many questions...any answers?!

 

thanks!!

[Mike at Vauxhall]

Probably alarm springs connecting the module to the diaphragm ( white disc on the back of the watch). Small tip, if you lose one you can trim down the spring out of a telescopic watch pin , works a treat.

[Lee]

 

"to reset after a battery change short this contact against this contact" - but I've never had to do this yet.

 

 

The "AC" (all clear) reset its a must, it does just that clears the watch to get everything in the right place. if you don't do it, it can affect things like the calender & even make a battery drain off super fast.

[Lee]

I just found this in my draw, this is the sort of sticker that you get on 90% of case backs that require an AC reset

 

 

So its worth looking out for it, its generally on chronographs or simular multifunction movements, but its always worth looking closely at the movement as you change the battery, because occasionally the watch won't have a sticker.

 

Lee