Steve sent in his EternaMatic Triple Date for a service. This watch has quite a few complications:
- moon phase
- 3 register chronograph
- 24 hour hand
- sub-second hand
- hacking second
- quick-set date
- quick-set moon phase
- quick set day
From the top: the top sub-dial shows the day of the week on the left, and the month on the right. A lot of triple dates require you to manually forward the month, but this one does it automatically on every 31st. If the month is shorter, you have to advance the date by hand. It also has a hand for the minute recorder of the chronograph.
The sub dial at 9 o’clock has a short hand showing a 24 hour display (just in case you can’t tell if it’s day or night) and a longer second hand.
The date is shown by a central date hand with a crescent shaped red end.
The sub dial at 6 o’clock shows the moon phase, and the hour recorder hand. A total of 8 hands!
This EternaMatic is in a solid gold case.
Not too bad, but it’s been a long time since the last service, and the movement is dry.
Readers who are familiar with this blog will recognise the movement – it’s a Valjoux 7751, derived from the 7750.
The bottom plate with the day and month wheels at the top, the date wheel in the middle with 31 teeth, and a single tooth to advance the month wheel. Below the moon phase wheel with 59 teeth (=29.5 days between full moons). This isn’t very accurate, but the error is such that it only requires correction once a year.
I start off with the plate that covers the auto winder and parts of the chronograph.
At the top, the rose coloured wheel drives the click wheel to wind the mainspring. The bronze coloured wheel below is the reverser wheel (only uni-directional winding in this movement), and in the middle is the central chronograph runner. To the right of that the hammer to reset the second and minute recorder to 0, and below it the minute recorder.
One layer down….
The chronograph layer is almost gone, and we can see the intermediate winding wheel at the top left.
One plate down, and we are at gear train level. The silver coloured strip of metal in the middle is the hacking second lever that stops the balance when the crown is pulled out.
The top plate is almost cleared, and I turn the movement around.
Time for the triple date layer.
With the discs gone, you can see the little runners and gears that drive them.
The T-shaped lever at 9 o’clock drives the moon phase disc by one tooth every day.
Time to remove the next plate.
We are now at hour recorder level, and back to chronograph function.
Almost done taking apart the movement.
With the amount of complications, you get a lot of parts to go along with it.
Re-assembly starts with a new mainspring.
As always, I start with the base movement. No use putting anything else on until I’m sure that the movement is performing well.
And it does indeed. Now I can start to put the chronograph back together.
And that’s tht done – only the rotor is missing from this side of the movement.
Now I can start on the first leel of the bottom plate. I start with the winding mechanism, and the clutch at 8 o’clock. The first components of the triple date mechanism go in.
The moon phase lever at the top.
Ready for the wheels.
Day, month and moon phase discs are in.
With the dial and hands on, I case the movement.
Looks great in the gold case!
Yes, it’s 18k gold.
The movement has settled in, and shows the usual Valjoux 775n performance. They always do, and in my book, are the best performing chronograph movements.Having put 8 hands back into place, the watch is ready for testing.