Owner manual / English
OLD WATCH SHOP
Casio Module 20 Manual
One owner's manual PDF for the Casio module 20 in English. Casio's spec sheet lists one 393, with 12 months of battery life and accuracy within ±20 seconds a month; the module first shipped in Oct 1977.
Module specs
Battery: 393 (silver-oxide)
Rated battery life: 12 months
Rated accuracy: ±20 sec/month
Casio service manual ref: S/M-103
Open Casio battery finder
