Seiko Calibre 3B21A Solar Radio-Controlled Quartz Movement

Restore a compatible watch with the Seiko Calibre 3B21A solar radio-controlled quartz movement, featuring hour, minute, and central seconds hands.

This movement converts light received through a compatible solar dial or panel into electrical energy stored in a rechargeable secondary battery. When correctly assembled, it can synchronize the displayed time by receiving Japan’s JJY standard-frequency radio signals from the Fukushima and Kyushu transmitting stations.

Automatic radio reception is normally attempted at approximately 2:00 AM, with another attempt at approximately 4:00 AM if the first reception is unsuccessful. Manual signal reception is also supported.

Product Specifications

Product Type: Analogue Solar Radio-Controlled Quartz Movement
Manufacturer: Seiko
Calibre: 3B21A
Display: Hour, Minute and Central Seconds
Calendar: No
Radio-Signal Compatibility: Japan JJY 40 kHz and 60 kHz Signals
Radio Reception: Automatic and Manual
Time-Zone Adjustment: Yes
Quartz Frequency: 32,768 Hz
Accuracy Without Radio Synchronization: Within ±15 Seconds per Month
Operating Temperature: −10°C to +60°C
Driving System: Separate Step Motors for Hour/Minute and Seconds
Power Source: Rechargeable Secondary Battery
Operating Duration: Approximately 6 Months from a Full Charge
Maximum Duration with Power Saving: Approximately 18 Months
Energy-Depletion Warning: Yes
Power-Saving Function: Yes
Automatic Hand-Position Correction: Yes
Reception-Level Display: Yes
Reception-Result Display: Yes
Electronic Circuit Reset: Yes

Radio synchronization operates only within supported JJY reception areas and depends on location, signal conditions, building structure, electrical interference, and correct movement assembly.

Please compare the complete calibre marking, movement dimensions, hand fittings, stem and button positions, antenna configuration, rechargeable battery, solar panel, dial construction, and movement holder with your existing components before ordering. Professional installation is strongly recommended.

Package Contents

1 × Seiko Calibre 3B21A Solar Radio-Controlled Quartz Movement Only

Important: The rechargeable battery, solar panel, winding stem, and all other accessories are not included.

Seiko and its associated marks are trademarks of their respective owner. The name and calibre reference are used solely for accurate product identification.