The Doxa 103 is a high quality swiss handwinding movement of 11 1/2 lignes,
which bases on the ETA 2391.
You can easily see, that the Doxa 103 bases on the ETA 2391, when you compare the
inner workings. Their construction is identical, in both cases, the minute wheel is
driven on the dial side via the third wheel. This wheel is driven by the
fourth wheel with its thick axles and trains, which itself is driven by the
mainspring barrel.
inner workings
The center second is direcly driven. As you can see, the arrangement of the wheelworks
is quite clever, using as few space, as possible. On the large 11 1/2 ligne main plate,
there's a lot of solid, unsed space, which is a result of the fact, that the ETA 2391
is nothing but an ETA 2390, where the main
plate is extended from 10 1/2 to 11 1/2 lignes, while the rest stayes the same.
main plate
The golden toned Glucydur screw balance is not yet shock protected, but
carries a blue Nivarox-I hairspring, whose end is connected to a moveable
stud. Altogether this was among the best things, which were available on the (mass-)marked
at that time.
Nevertheless, there's a little downer: The Doxa 103 lacks any kind of find regulation,
which means, that the effective length of the hairspring can be adjusted directly at
the hairspring key only. This very cheap and crude mechanism does not fit into the
picture of the otherwise high quality made regulation organ.
gold toned Glucydur screw balance with Nivarox-I hairspring
The Glucydur screw balance is a feast for the eyes!
dial side view
On the dial side, there's ETA everywhere: The yoke winding system, the second wheel which its
visible teeth at "7" and the massive axles, the third wheel, which indirectly drives the minute
wheel at position "7:30" and last but not least the ETA-typical spreading spring on the hour wheel,
which prevents it from slipping on shocks.
The partial minute dial on the lower part of the dial side plate indicates, that this movement
is pretty old, since it was used in times, when timegraphers were not yet avilable everywhere, and
helped the regulator to adjust the movement without mounted dial.
Technical data
Manufacturer
Doxa
Caliber
103
Number of jewels
17
Escapement
Anchor with pallets
Balance
Glucydur screw balance
Shock protection(s)
none
Balance cock direction
clockwise
Hairspring stud
moveable
Regulator type
Hairspring key
Movement construction
Fork Escapement wheel, Fourth wheel, Third wheel, Large driving wheel Mainspring barrel
Construction type
solid construction
Bridge shape
Triangle, rounded shapes, 4 gears
Winding mechanism
yoke
Setting lever spring
4 holes
Features
SCD
Functions
Hour, minute, second
Beats per hour
18000
Size
111/2''' (measured: 25,6 mm)
Image in Flume Werksucher
K2 -
Factsheet
Test Results
The movement came completely gummed into the lab, sealed in a watch wreck (see
below) and hence got a full service.
Nevertheles, the movement has got a tiny problem: Since the gears are so near to
each other and tend to "tumble" a bit, they tend to touch from time to time, slowing
down the movement a tiny little bit.
It's likely possible, that this problem originates from the bad treatment, it got
over the years.
Timegrapher Protocol
On the timegrapher, which printed here in double precision, the movement
performed not bad, but still far beyond its possibilities.
While on the horizontal positions, the deviation is pretty low (at max. +15 seconds
per day), three of the four vertical position show a bad performance, down to
-45 seconds per day. It's quite possible, that this is due to the slightly
"tumbling" gears. In the vertical positions, any gear will start tumbling, if no
cap jewels are used. And if the gears are not 100% straight, you will see these
problems. Unfortunately, the Doxa 103 lacks cap jewels, except one on the escapement
wheel.
