This watch was a bit of a pain to sort out. The calendar system on the 6619 movement is a little weak, so I ended up replacing and adjusting a few components there to get the date change working correctly. Besides that, the watch got a new crystal, movement service and a new set of seals. The 6619 movement tends to be quite noisy when winding.
This watch was fully serviced, glass refurbished, seals replaced and has some minor work done to the dial to remove corrosion. Lume was in good condition and left alone.
This photo shows inside the SEIKO 7A28 movement. Here you can see the keyless works, micro motors and gear train that operate the watch.
Each of the copper coils runs a tiny motor that operates each hand on the watch. In the middle, the gear train does to work to run the minute and hour hands, which are driven by friction off the second hand.
The micro motors are not unlike a standard electric motor that you would have in a power drill or other household appliance. They are just on an absolutely tiny scale.
When the hands are supposed to move, the circuit (which sits on top of this assembly) sends a small voltage through to the copper coils, which create a magnetic field and turn the motor.
The 7A28 movements were the first quartz analog chronograph movement in the world and are extremely well built.
You can see a dent on one of the copper coils here, which was done during a previous service. Luckily it has not broken the extremely fine wire which is thinner than a human hair. These are easily the most delicate part of the watch movement.
This watch received a full overhaul, re-lume and several parts replaced inside. The movement was also upgraded to 21 jewels. Several of the movement bushings were worn out so this was necessary to ensure it would run well.
The story goes these were inspired by some Japanese racing driver in the 70’s. They have a unique case finish and bracelet. This one received a full rebuild along with the barrel arbor upgrade and hand restoration.
This watch came in very rough but came up a treat. It had the worst example of barrel arbor wear I’ve ever seen and was totally dead. The watch movement was serviced and the barrel arbor jewelled. The case was spun on a lathe to restore the circular brush finish and the crystal was replaced. The hands were heavily corroded and restored with a special solution + replacement of the luminous paint.
Another great looking watch. This one received a full movement rebuild and some replacement parts along with a replacement stem and crown. That had been broken in the past and was held together with glue and some strange metal parts. Because of this the stem did not work correctly and the keyless works were damaged.
This arrived recently. It’s a 7A28 quartz chrono movement and the case is quite unique, as you can rotate the case around a full 360 degrees. It’s designed as a driver’s watch so you can rotate the watch to suit the angle your arm is at.