How to ac reset Casio 5154 - Casio Watches

https://support.casio.com/en/manual/manuallist.php?cid=009

Enter the 4 digit caliber number on the back of your watch

Shortcut battery with AC contact. AC can be found on the sides of watch movement(very tiny). You have to use pointed tweezers: one end on battery+, another on AC contact for three secs...

Click on my profile (escapement), then click on Tips and Tricks. There you will find link to all CASIO watch manuals. Rate me, please .

To reset the battery you need to locate the "AC" inside your watch. The AC terminal is a little metal spot (usually a circle and usually gold colored) on the inside of your watch. Looking at the inside of your watch the "AC" should be labeled, though it may take a magnifier to identify it.
It may be labeled simply "AC" or it may have an arrow pointing to it. Once you locate it use a pair of tweezer or a paper clip and touch the battery and the AC together for a few seconds and release; you may have to do this twice. This will reset your watch an give you the ability to correctly wet your watch.

This is an old problem, but maybe this will help someone changing a battery on a Casio. Many Casio watches must be "zeroed out" by putting an pointed tweezers between the back of the battery and the AC terminal off to the side of the battery. On my old Casio Telememo 50, the AC terminal is in a very small hole just above the battery. On the Baby G force, it was in a wider opening, way at the edge of the watch. It has something to do with resetting the watches circuitry so it will operate again. Good luck!

You need to shortcut AC point and battery. Take tweezers and touch AC and battery (+) simultaneously. Use an eyeglass to find AC point. It is marked on the movement with letters AC.
Here is the link for easy watch setting:

http://world.casio.com/wat/download/en/manual/

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Take the battery out again, wait for a few minutes, then replace it and shortcut AC and battery. After that you have to reset your watch completely. To find AC you will need an eyeglass.

Do not lay the tweezers across any contacts as you may damage the watch.
First you need to examine your watch movement and find an AC point (contact). Use an eyeglass, as the writings can be very tiny.
When found, touch an AC point with one arm of tweezers and battery+ with another arm simultaneously.
Some watches needs to do that twice, so, to be sure, do that twice.
If you are not comfortable with tweezers, you can use a thin wire, connecting one end of the wire to AC point and another to battery+.
Each shortcut should last for 3 seconds.

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On most casio watch you can see AC (all clear) point , youy need to resset clock connecting this point with + on battery about 5 sec.

I have same problem but on my watch I do not see AC point. :)

regards
ststefan

This reset trick works with other Casio Alarm Chrono digital watches, such as my old Model W-720, similar to your F91-W. After the new lithium coil cell is installed and secured with the spring clip, the watch may show random segments in the LCD display or may simply be blank. Insert a sewing needle, paper clip, or blade of a small jeweler's screwdriver into the hole on the back of the movement stamped "AC" (All Clear) to momentarily connect the gold plated contact at the bottom of the hole to the stainless steel battery clip. The battery clip in most such Casio watches is connected to the "+" terminal of the coin cell. This will reset the CMOS chip and it should start up with the watch displaying 12:00 and the date at 1-1. Then, use the control buttons to set the time and date in the normal fashion.