Casio MD-502 Battery Change

I recently picked up this little beauty, a Casio MD-502 Quartz dive watch, that I believe to be a JDM model, and straight out of the 80s!  I’m a big Quartz fan, especially the dive watch sort, so when I spotted this for sale at a bargain price I couldn’t resist it! 

A few days later the watch arrived and I set the hands to ten past 10 for the obligatory Instagram photo. 

Obligatory ten past ten shot

Shot taken and posted to Instagram, I went about the rest of my day. A few hours later I went back to the watch to find the time was only showing as 10.50 and had stopped ticking altogether. A few taps and winding the hands back and forth didn’t unstick anything, so I assumed that the battery had decided to expel its last bit of charge just after it arrived with me! I was heading to town the next day anyway, so I grabbed a battery whilst I was out and set about changing it to get my new diver ticking nicely again. I photographed the battery change procedure to post here, the photos are not the best, but in my defence I was getting ready to attend an 80s vs 90s party night and was planning on wearing this as part of my 80s attire, so whilst I didn’t rush the battery change, the photos may have been a bit rushed! 

The watch has a screw down case back so I assembled the tools I would need for thebattery  change. 

Tools at the ready

First job was to remove one end of the jubilee bracelet to give me access to the case back. 

Using a Bergeon spring bar tool to remove the bracelet

Caseback removed and the internals of the watch were exposed. 



As you can see, there’s a big plastic spacer surrounding the movement which looks like it also holds the battery in place in the absence of any sort of battery clip. 

What surprised me here wasn’t the fact that the movement didn’t have any jewels in it, but the fact that Casio went to the length of printing the fact that there’s no Jewels on the movement! 


With the old battery removed, (and yes, I did place the battery on the tip of my tongue to test that it was flat) I got the new battery out ready to fit. This Seiko branded battery cost me the princely sum of 30 pence! 

30p for a Seiko branded battery, result!

Battery and plastic spacer both fitted the next job was to turn my attention to the case back gasket. 

Case back and gasket

The gasket seemed to be in pretty good shape, which was a good job as I had no way of replacing there and then if it required replacement. A quick coating of silicone grease to enable the case back to be screwed down tightly and I was going to be confident that the watch would be reasonably water proof. It’s not the sort of watch I would risk taking any deeper than the bottom of the dish bowl,so water resistance want a primary concern of mine. 

Silicone grease ready for application

Caseback replaced and this little Casio dive watch was happily ticking away again, I even managed to get it out back together before Mario took his hammer to it! 


And the wrist shot you’ve all been eating for: