ISA caliber 8173A is 9 jewel quartz movement. ISA refers to this as a multi-function movement because it features a GMT hand, alarm, day, date, and power reserve indicator.
Swiss Made or Far East?
ISA labels the caliber 8173 as Swiss made or Far East. Both have 9 jewels. Check your movement to see if it is stamped SWISS MADE or FAR EAST ASSY.
Estimated Battery Life
ISA claims that the power reserve from a fresh battery is approximately 39 months. If you use the alarm, your expected power reserve may decrease to 35 months.
Installing a New Battery
There is a gold tone metal tension clip holding the battery in. You will need to gently unscrew the screw, but do not unscrew it completely. Then carefully slide the hook side off of the screw, be very careful because it can jump out!
After installing the fresh 395/399 battery cell, put the tension clip back on. Look at the picture below to see where the tension side goes into the hole on the movement. Slide the hook around the screw, holding it in place while you tighten the screw back down.
After replacing the battery, you may need to perform the following reset procedures:
After battery insertion, or if movement does not work correctly after battery setting, a reboot can be carried out by connecting the indicated capacitor with metallic tweezers. This operation is far better than removing and reinserting the battery and thus ensures a correct restart of the movement.
After that, the movement is in the same configuration as after a battery change and an initialization procedure has to be carried out as described previously in this instructions manual.
At the time of this post, this movement was found at replacement prices of $39.95 – 52.95 USD.