To open the watch and remove the back of the watch, best use the pocket knife, or similar tool – which the blade is thick and not too sharp.
First you need reverse the watch.
The notch on the blade of pocket knife you will find in the lower right corner of the watch.
Notch in close-up …
I have already opened the watch …
The battery you need is classical alkaline battery SR 1120W . I recommend Silver Oxide Battery ( marked as SR1120SW with an additional letter S – silver ) – longer works and does not leak !
Don’t buy the cheapest battery, unknown manufacturers. I recommend RENATA, VARTA, MAXELL, SONY, SEIZAIKEN ( Seiko Instruments ).
Although today the batteries supplied by unknown manufacturers could have a similar capacity ( 55mAH ) even well-known producers ! However, they will almost certainly leak out especially at higher temperatures ~ 30 °C (~ 86 *F). It is not very dangerous because the contact-plates are coated with gold and the others are acid-resistant, the plastic is also resistant to acid. I know from personal experience that the acid doesn’t cause any serious damage. After two years of using cheap batteries I just had to wipe the acid – battery and the watch still worked ! However there is a risk due to an acid condensation occurs from the inside glass. Of course, it can be cleaned, but it may be for you a little problem. Better to pay extra few cents and buy the proven battery :)
The battery is covered by a small plate – mounted on two small holders .
Removed plate and her holders.
To remove the battery cover, preferably use a small screwdriver. Just simply slide the metal plate from the holder on the one hand. Now, the plate itself will remove.
The case back ( with visible piezoelectric beeper „piezo buzzer” ) and rubber seal close-up …
„This is a sporting watch witch water – resistance up to 10 atmospheres of pressure „ i.e. 100 m – Citizen’s words .
So, before closing the watch I recommend cleaning the gasket :) .