Seiko Cal. 4205B, 4206B, 4207B Parts Catalogue/Technical Guide

Seiko Cal. 4205B, 4206B, 4207B Parts Catalogue and Technical Guide — a comprehensive service reference for professional watchmakers and technicians working with these popular automatic movements. This workshop manual covers specifications, disassembly and reassembly procedures illustrated with numbered parts diagrams, detailed component drawings, and complete technical data. Movement specifications include 17.5 mm outside diameter, 17.2 mm casing diameter, and 5.6 mm height; all three calibers feature three-hand time indication, automatic winding with manual hand-wind capability, and 21,600 vibrations per hour (6 beats per second). The calendars differ by model: 4205B offers date-only function with 17 jewels; 4206B and 4207B both include day-and-date complication, with 4206B carrying 17 jewels and 4207B fitted with 21 jewels for higher accuracy. The guide provides detailed parts lists keyed to exploded diagrams, step-by-step disassembly and reassembly figures, lubrication specifications for each component, and practical technical notes essential for correct service intervals and repair work.