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Service Manual · Heritage 1854

The
Model 51

9¾ by 12¾ Ligne Electronic Calendar · Model 50 Base

The Model 50 with a calendar mechanism added. A finger on the date wheel moves the date ring, a detent spring holds it and helps carry it, and the date can be set by hand in either direction.

Electronic Calendar Model 50 Base Set Either Way
The Model 51 movement, dial side and movement side
Factory Service Manual · Model 51 · Dial Side & Movement Side
Technical Specifications
Ligne9¾ × 13½ (cover) · 9¾ × 12¾ (text)
Dimensions22.1 by 30.5 mm
Basic movementModel 50
TypeElectronic calendar
Date settingManually, forward or backward
ManualService Manual · Model 51
Height6.20 mm
Jewels3
Height and jewels: ranfft.org

A Calendar on the Model 50

The Timex Model 51 is an electronic calendar movement. The Model 51 movement is the same as the Model 50 movement except that a calendar mechanism has been added. The date can be set manually, either forward or backward, by rotating the hands.

The one difference in servicing: Basic servicing techniques are the same as for the Model 50, except that the minute hand should be removed prior to removing the dial. For the electronic movement itself, its contact system, its diode and its train, see the Model 50 guide.
Caution: Since the watch contains permanent magnets, no attempt should be made to demagnetize it.
Timex Model 51, dial side
Dial side
Timex Model 51, movement side
Movement side
Photos courtesy of ranfft.org

Exploded View

Everything below the numbered parts is the Model 50 electronic movement.

Model 51 movement, exploded view
Model 51 · Calendar Parts
Ref.Component
145Dial Rest
206Center Wheel Assembly
498/1Hour Wheel Washer
751Dial
850Hour Hand
851Minute Hand
852/1Sweep Second Hand
2556Date Wheel Assembly
2557/1Date Ring
2558Hour Wheel
2576Detent Spring

The Date Mechanism

How It Drives

•

A finger attached to the date wheel assembly engages with and moves the date ring.

•

A detent spring holds the date ring in position and also aids in moving the date ring.

•

A pinion attached to the hour wheel, 2558 on the exploded view, engages with the date wheel assembly.

Note: Use the exploded view as a guide in disassembly and assembly of the mechanism.
The detent spring, dial rest, date ring, date wheel assembly and center wheel assembly
Fig. 51.3 · Date Mechanism

Cleaning & Lubrication

Dial rest, July 1976: the same spreading type lubricant used on the Model 254 (Woods AAAA oil) may be applied to dial rests which have solid film lubricant, between 3 and 6 o’clock on the inside corner. Service Bulletin No. 112
Lubricant change, June 1974: Timex Service Bulletin No. 111 replaced the factory oil for this model. Moebius Synt-A-Lube oil is used instead of Elgin M56B oil. (It supersedes Bulletin No. 108.)

All cleaning and lubricating points indicated for the Model 50 should be followed for the Model 51. In addition to the Model 50 lubricating points, lubricate a few teeth on the date ring and the post of the date wheel. The dial rest has been coated with a solid lubricant and needs no further lubrication.

The date ring is a printed dial: remember that the date ring actually is a printed dial, and some watch cleaning fluids will strip the printing.

Positioning the Hands

1

First: set the finger on the date wheel assembly against the date ring as shown in the figure above.

2

Next: replace the dial assembly together with the hour hand, keeping the hour hand set at the 2 o’clock position.

3

Finally: replace the minute hand and sweep hand.