A costumer has sent in his lovely citizen calibre 8100. This is a real fly back automatic chronograph that citizen developed to fight Seiko’s 6139. It’s not resetting correctly and needs a service.
Movement looks to be in good condition.
Watch is running, but not great.
I remove the osculating weight.
The reset lever is situated underneath the chronograph bridge.
Like the Seiko 3169, the citizen 8100 has a clutch on the chronograph wheel.
I take the movement out of the case. Beautiful purple sunburst dial.
I remove the hands and dial and you can see the day/date disks.
Underneath the day disk you can see the day/date mechanism.
Here you can also see the setting/winding mechanism.
I start taking the base movement apart.
Movements sometimes look clean, but once you start taking them apart you find the dirt.
Here you can see the gear train layout.
I clean the movement and fit the mainspring back into the barrel after lubricating it.
I fit the cap jewels and see that the balance moves freely.
I put the base movement back together.
I put the resetting mechanism back together.
Base movement and chronograph almost back together.
I put the setting/winding/date/day mechanism back together.
Movement goes back into the case.
I’m happy with the performance.
I find this movement exceptionally well made and a step up from Seiko’s 6139 because it’s thinner, has a fly back mechanism and you can manually wind it. Also I like the 6139!!
Great looking watch!