Seiko Epson Date Code Marking ~repack~ Page

Understanding the system is essential for verifying product authenticity, checking warranty status, and managing electronic component shelf life. While the Seiko Epson Corporation uses various marking formats across its diverse product lines—including quartz crystals, semiconductors, and printers—most follow specific alphanumeric patterns to denote the year, month, or week of manufacture. Crystal and Oscillator Date Codes

The second character represents the month. Digits 1–9 are used for January through September, while A , B , and C represent October, November, and December. seiko epson date code marking

A three-digit variant where one digit is the year and two are the week, common on smaller devices. Component-Specific Identification Understanding the system is essential for verifying product

Before diving into the specific alphanumeric sequences used by Epson, it is essential to understand why date codes exist. In the electronics industry, components do not last forever. Solderability degrades over time, quartz crystals can drift, and chemical compounds within integrated circuits can change. Digits 1–9 are used for January through September,

Epson products manufactured in Japan (Suwa plant) use different formatting than Epson products manufactured in the Philippines or Indonesia. Japanese date codes often shift the year to the end of the string.