How do you get the back off?

You need two SR1120 or type 391s.

Remove the back cover of the watch. You probably do not need a special tool to do this. The battery is likely right on top, held by a metal clip. Note the "polarity" and orientation of the battery, i.e., which end is up (take a picture, if necessary). Carefully remove the battery by gently prying up the clip that holds it in place. The battery type is engraved on it, and you will need to get a replacement of the same type or an exact equivalent. You could purchase one on-line or from Radio Shack.

With the replacement battery in hand, insert it back into its cutout within the watch mechanism, again gently prying up the clip. Make sure it's oriented the same as the original battery. Replace the watch back -- you may need to press down to make it click into place.

If you don't already know what size battery you need, you can find this information on the back plate of your watch. Once you have your replacement battery, you will need to open the back of the watch to gain access to the battery compartment. Depending on the watch, the back plate will either screw off or be attached by a few small screws. If attached with screws, you will need a set of precision screwdrivers such as a jewelry or eyeglass kit.

Inside the battery compartment, you will see the battery is held down by a clip. Carefully remove the clip and eject the battery. Insert the new battery and replace the clip. If the battery clamp indicates you should do so, quickly press the reset button twice. Then reattach the back of the watch. If the watch display remains off after replacing the battery, press all buttons at the same time to reset the display.

BASIC WATCH BATTERY CHANGE
Get a replacement battery for your watch. Some watches have the battery information stamped on the back plate. If yours doesn't, you'll have to wait until you've removed the old battery to see what kind of replacement watch battery you'll need.
Lay your watch face down on a non-scratching, non-skid surface. It may help to clamp the watch to the surface.
Remove the back from the watch. You might be able to pry it off with your fingernail, but you'll probably need a stiff, thin tool like a knife or screwdriver. You can also buy watch repair kits, which have the perfect tools for the job. Check the watch back for a small notch to insert your tool, but not all watches have these.
Remove the battery from the watch once the back is off. You might need to tip the watch over to let the battery fall out.
Insert the new watch battery into the proper space, first double-checking its size against the old battery to make sure it will fit. Press lightly into place.
Replace the back on your watch. Make sure you press firmly to get the back seated snugly.

If this doesnt work, then take to a local jeweler/watchmaker who is equipped with the right tools to assist you.

Best regards.

The most water resistant watches will have a screwed down case back and crown for maximum water resistance, both of which are backed by internal gaskets. These are the types this articlde will concentrate on. To change the battery in a water resistant watch you will need:

• Adjustable case tool
• Case holder ' + google_ads[0].line1 + '
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• Small screw driver
• Polishing cloth
• Cotton gloves
• Small tweezers
• Plastic tweezers
• Soft clean cloths
• Battery tester
• Paper cup

1. Place the watch in case holder. Place the watch in the case holder, if you have one. If you do not, place it on a soft cloth.
2. Check for room to work. Check to see if there is room to attach the adjustable case wrench and rotate it 360 degrees. If not remove watch band.
3. Remove case back. Fit the adjustable case wrench into the slots on the case back. Tighten it down until it is snug. Be careful not to slip with this tool as it can scratch the case back of your watch. Work slowly. When it is unscrewed gently pry up the case back taking great care not to damage the internal gasket. If the gasket gets damaged it will need to be replaced with the battery to retain water resistance.
4. Remove battery. The battery will be held in place by some type of retention device. It will need to be removed. Some clips will be removed by using tweezers. Some clips may be moved using a screw driver, and some simply bend out of the way slightly. Remember how it was removed as it must be put back in place exactly for the circuit to be completed after battery change. If the clip is removed, place it and any screws in a paper cup to prevent loss. Remember how the battery was seated, plus (positive) side up or down etc. it needs to be replaced correctly to work.
5. Test battery. Using the battery tester check the battery. If it is dead move to next step, if it is not take the watch to a jewelers for inspection.
6. Clean and inspect battery box. Inspect the battery box the battery came out of. If there is corrosion take it to jewelers for inspection. If there is light dust it may be cleaned with a clean soft cloth.
7. Buy battery. Use the numbers on the battery and buy a new one. Occasionally the number will be obsolete and you will be referenced to a replacement battery in the battery charts. This is the time to also replace the gasket if you need to. Check with a watch maker or jeweler, or the watch company to buy a replacement. We cannot stress enough how important this gasket is to a water resistant watch, without its integrity your fine watch may no longer be resistant.
8. Replace battery. Using the plastic tweezers if you have them, or fingers wearing cotton gloves, replace the battery. Never use bare fingers as finger oils may corrode or short out the new battery. Carefully replace the retention device as it was remove.
9. Replace case back. Make sure that the gasket is in place, and not pinched or caught in the case back when you set it in place. Screw down the case back using your fingers until it is tight and needs the case wrench. Attach case wrench as before and tighten down the case back.
10. Reset and clean watch. Using the appropriate method reset the watch. Use the polishing cloth to clean off any dirt and finger prints.

OR...take to your local jeweler/watchmaker who has the appropiate tools and let them do it for you!!!! :)

mcdevito75 here, Those 4 screws hold the back onto your Timex. Do not try to pry off the back cover, rather you"ll need jewlers screwdrivers to un--screw that back cover to replace the battery.

Hi, I just encountered the same problem today as I was changing the battery and I found the solution. First make sure when you are changing the battery that the watch stem is pulled out; then after the battery has been replaced, and before you put the gasket and back on you will need to "reset" or "hotwire" the battery ....you are going to likely need a magnifying glass to find a tiny ac symbol on the back of the watch (without the back cover replaced)...just next to the ac symbol is a tiny hole. Take a piece of wire, or in my case I used an unfolded paper clip, and put one end of the wire in the hole and the other end on the back of the battery (the +/positive side should be facing up). Leave the wire in contact with the ac/battery for 5 seconds, then remove. Next replace the rubber gasket, then the back and the screws. Lastly, push in the watch stem. Your watch should now work. I found out through considerable research that almost all digital watches will need that "hotwiring" step performed after the battery is replaced.

dcraigpa