Seiko 1428A - Technical Guide
Seiko 1428A – Technical Guide (High Quality)
The Seiko 1428A is a manual-winding mechanical movement produced in the 1960s, tailored specifically for ladies’ wristwatches that require a compact, reliable, and elegant mechanism. Known for its slim profile and simple two-hand layout (hour and minute), the 1428A exemplifies Seiko’s dedication to precision engineering and durability in small-sized mechanical calibers designed for delicate watch cases.
1. Technical Specifications
| Feature | Details |
|---|---|
| Caliber Number | Seiko 1428A |
| Movement Type | Mechanical – Manual winding |
| Functions | Hour, Minute |
| Jewels | 15 |
| Beat Rate | 18,000 vibrations/hour (5 beats per second) |
| Power Reserve | Approximately 38–42 hours |
| Winding Method | Manual only |
| Hacking Seconds | No |
| Calendar | None |
| Diameter | Approximately 17 mm (~7¾ lignes) |
| Movement Height | Approximately 3.3 mm |
| Shock Protection | Basic or none depending on variant |
2. Key Features
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Two-hand display focusing on hour and minute hands
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Compact and slim design ideal for elegant and delicate ladies’ watches
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Reliable manual winding mechanism with smooth crown operation
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15-jewel construction reducing friction and wear
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Absence of seconds hand and calendar complications simplifies mechanism and maintenance
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Service-friendly design facilitates repair and upkeep
3. Operating Instructions
Manual Winding:
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Wind the crown clockwise daily until resistance is felt; avoid overwinding
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Full wind yields a power reserve of approximately 38–42 hours
Time Setting:
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Pull the crown out to the setting position
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Rotate crown to adjust the hour and minute hands
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Push crown back in to resume normal operation
4. Movement Architecture
Dial Side:
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Hour and minute wheels along with cannon pinion
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Basic keyless works for time adjustment
Train Side:
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Mainspring barrel with ratchet and click spring
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Gear train consisting of center, third, and escape wheels
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Pallet fork and balance wheel assembly with flat hairspring
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Regulator lever for timing adjustment
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Limited or no shock protection in some versions
5. Servicing Recommendations
| Service Interval | Every 4–6 years |
|---|---|
| Cleaning | Full disassembly and ultrasonic cleaning |
| Lubrication | Train wheel pivots, escapement, balance jewels |
| Regulation | Adjust via regulator lever aiming for ±30 seconds/day |
6. Common Issues & Troubleshooting
| Issue | Likely Cause | Solution |
|---|---|---|
| Watch stops prematurely | Dried or dirty mainspring | Clean and lubricate; replace mainspring if needed |
| Timekeeping irregularities | Magnetized or dirty balance pivots | Demagnetize and clean pivots |
| Loose or slipping hands | Worn cannon pinion | Refit or replace cannon pinion |
| Low amplitude | Dirty jewels or weak mainspring | Service movement and replace parts if necessary |
7. Typical Applications
The Seiko 1428A was predominantly used in:
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Ladies’ wristwatches with small, slim cases (~17–22 mm diameter)
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Elegant dress watches with minimalist dials
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Polished steel or gold-plated watch cases
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Timepieces without seconds or date complications
8. Historical Context
The 1428A reflects Seiko’s commitment in the 1960s to:
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Developing precise, durable, and compact mechanical calibers for ladies’ watches
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Balancing slim form factor with reliable mechanical performance
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Establishing a foundation for future movement innovations
9. Conclusion
The Seiko 1428A is a well-engineered, elegant manual-winding movement prized for vintage ladies’ watches. Its two-hand simplicity, slim design, and sturdy mechanical construction make it a favorite among collectors and watchmakers. When properly maintained, the 1428A delivers graceful and dependable timekeeping, epitomizing Seiko’s mid-20th century watchmaking excellence.
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