SEIKO 3923A VFA LED QUARTZ 1973
The Seiko 3923A (day-date version of cal.3922) is an awkward one of a kind mix of early quartz and LED technology. Pieter Doensen's database indicates market launch in January 1974 whereas the serial number on this piece is September 1973 but other sources also mention 1972 (still produced in 1975). The 39SQW series was made by the Daini Seikosha factory and thus had a far different construction than the 38SQ Suwa series with stepping-motor. Both were very expensive (¥150.000 vs ¥98.000) and precise with the Very Fine Adjustment V.F.A. The red LED applied on the dial must have been revolutionary at that time but unfortunately it did not have much in common with the American LED watch revolution and only serves as a pulsating power indicator. Still this concept is quite unusual what makes the watch very collectible.
The diamond faceted LED indicator lights up faintly every second in line with the tick of the seconds hand... although you need to view it directly from top to even notice the blink ;) This minor flaw is compensated with a cool overall design and high craftsmanship in every detail. The dial is a piece of art with triple brushed finish and huge raised hour indexes. Compared to many kitchy 70's watches this steel model looks nice despite having golden hands, applied Seiko logo and 12 hour index. The 50xx case is also unusual and opened by pushing two leaf-springs hidden between the lugs. The mineral faceted crystal mounted in a steel frame is made of lightly tinted glass with Quartz logo printed on the inside. The movement is removed from the thick caseback after unlocking the stem with a pin inserted in the hole at 2 o'clock.
Now...the movement! One of a kind, quite complex but smartly arranged using all the available space provided in the case with 1/3 for the batteries insulated in smart rubber bands. Upon removing the batteries and electronic substrate (with chips and quartz) you get access to the motor and gear train mounted in between 4 bridge plates! The motor is the biggest surprise as it is not a step-type as in the parallel Suwa 38SQ. The concept of an electromagnetic escapement motor is in line with the Roamer MicroQuartz and Omega MegaQuartz but with two extremely large coils. This approach might have been caused by backlash issues on immature stepping-motors or indicates that the 39SQ can be an earlier development than the 38SQ.
The exposed motor assembly is shown to the right. Two electromagnetic coils (0,78kOhm resistance each) attract/retract a 1-pallet arbor assembly with permanent magnet plate affixed to a pinion (shown at 6 o'clock). Each move of the esacapement arbor advances a 60-teeth escapement wheel by one tooth after which the arbor returns to it's original position. The ruby pallet on the arbor is affixed to a flexible finger (like an Accutron index finger) whereas the opposite counter-weight of the arbor moves in between two ruby bankings. The bankings (top-right corner in picture) are mounted on the bottom side of the bridge plate and are adjustable with screws from top of bridge. The other ruby pallet (shown at 9 o'clock) looks like a real anchor but serves only as a backlash pin (like Accutron pawl finger). Zoomed view here.
Keywords: seiko led, seiko vfa, seiko 3923A, seiko 3922, seiko quartz
Market value: 350$-750$-1000$ (model, condition, vfa box)