Seiko 4M21A Movement Parts Catalogue and Technical Guide
Seiko 4M21A movement parts catalogue and technical service guide for watch technicians and repair professionals. This comprehensive reference provides complete specifications for the 4M21A automatic quartz movement—a compact 26.4 mm diameter, 2.7 mm height unit with 3-hand configuration. Covers the step motor driving system with load-compensated pulse control, automatic power-generating mechanism, reserve indicator function, and both overcharge prevention and energy-depletion warning circuits. Includes detailed exploded view diagrams with all 46 numbered component parts clearly identified for accurate disassembly and reassembly work. Contains practical lubrication specifications for Moebius A and SEIKO Watch Oil S-6, plus step-by-step procedure references for safe teardown and rebuild. Details movement performance: 9 jewels, polyacene lithium capacitor power supply, approximately 72-hour charge duration, and 0.5–2.3 V operating voltage envelope. Essential workshop manual for anyone servicing Seiko automatic quartz watches with this movement.
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Document Details
- Format
- Pages
- 4
- Size
- 2.4 MB
- Category
- Watchmaking