Epson YM04A Guide

Watch Movement Specification and Drawing
CHRONOGRAPH
Cal. YM04A
Movement Size
Casing Diameter
Height
Battery Life
12’’’
Ø 27.0mm
4.93mm
5 years

Date: 11/Jan./'19
Cal. YM04A
Items Rev. Page
Specifications 02 1
Appearance 02 2
Casing 03 3
Hand fitting 02 4
Hand setting stem 02 5
Dial 01 6
Holding ring for dial 01 7
Attention for assembly 03 8
Attention of casing part structure 02 9
Operation-01 01 10-01
Operation-02 01 10-02

Date :
1. MOVEMENT DIMENSIONS
Outside diameter φ27.60mm (12H-6H) ×24.00mm (3H-9H)
Casing diameter φ27.00mm (12H-6H)
Total height 4.93mm (including battery)
2. TIME STANDARD
Type of quartz oscillator Tuning fork
Frequency of quartz oscillator 32,768 Hz
Accuracy ±20 seconds per month (on wrist)
Operating temperature range −5℃to ＋50℃
Regulation device Nil (Pre-adjusted)
3. INDICATOR / FUNCTIONS
3 Hands Hour / Minute / 1/5 second chronograph (Center)
Small hands Small second (9H) / Minute chronograph (6H) / 24 Hour (3H)
Calendar Big size date calendar (12H)
Instant setting device for date calendar
Reset switch
Power depletion warning function (BLD)
(Small second hand moves at 2-second intervals)
Chronograph
4. FEATURES
Jewels 0 Jewels
Anti-magnetism Over 1600A/m (Direct current magnetic field)
Maximum unbalance of hands Small second hand : 0.03μN･m
24 Hour hand : 0.03μN･m
Minute chronograph hand : 0.03μN･m
1/5 second chronograph hand : 0.09μN･m
Minute hand : 0.7μN･m
Moment of Inertia 1/5 second chronograph hand : less than 0.2μg・m²
5. BATTERY
Type / Size Silver oxide battery /φ9.5mm ×t 2.73mm
Recommended battery SR927SW
Nominal voltage 1.55 V
Battery life Approx. 5 years
(2 hours chronograph operation per day)
Driving current consumption Approx. 0.80μA
Operation stopping voltage 0.9 V
6. SEPARATED PARTS (Parts code)
Hand setting stem 0351584 (Standard) or 0351585 (Long)
Holding ring for dial 0866854 (Standard)
Battery SR927SW
7. TEST OF ACCURACY
Equipment to be used SEIKO quartz tester QT-99, QT2100
Greiner quartz timer-C , Witschi Q-tester 4000
Duration of measurement 10 seconds
Microphone to be used Electromagnetic detection type
All specifications are subject to change without notice.
Analog Quartz 12''' Big date Center second Chronograph Movement
Cal.
Rev. : 02
30/Jan./'15
YM04A Specifications
The chronograph can measure up to 60 minutes in 1/5 second
increments, capable of timing 12 hours.
P. 1

Date :
1.How to replace the battery
・Please use the specified battery to keep the stable performance for a long time.
・Please install the minus part of the battery towards inside of the watch.
・
・Install the battery under the circuit cover as illustrated below Fig.[1] and Fig.[2].
・System-reset is not required.
・
2.How to remove the stem
・
3.Attention to adjust the date
・Don't touch the date disks.
・When adjusting the date, don't turn the date disk directly by finger.
4.How to set the hands
・
・Do not turn the hand forcibly.
・Set the hour and minute hands on the date between "02-08".
5.How to remove the hands
・When removing the hands, use exclusive fork-shaped tools.
・Do not remove the dial under the condition that any hands are set.
6.How to test the accuracy
When measuring the time accuracy, use specified Quartz Tester and change the gate time in 10 seconds.
When installing or changing the battery, it is recommended to remove two battery clamp screws first,
then remove the battery clamp not to damage the movement parts.
If you install the battery without removing the battery clamp, please install the battery from [→] direction
as illustrated below Fig.[1].
After installing the battery, set the current time and then set the 1/5 second chronograph hand and
minute chronograph hand at "0" position.
When removing the stem, pull out the crown at 1st click position and then remove the stem while
pressing the hollow portion of setting lever by tweezers. (Refer to the Fig.[3].)
Each hand moves at step interval. Set the each hand at correct position according to the scale on the
dial in order not to make a mistake in reading time.
Cal.
YM04A Attention for assembly
15/Dec./'17
Rev. : 03
ABattery
Battery clamp Circuit cover
Fig.[2] A section
Fig.[1]
Fig.[3] Crown pulled out at 1st click
P.8

Date :
1.Minute hand
2.Holding ring for dial
3.Case
The center wheel have a safety stopper structure to prevent the minute hand from being pressed too
much. However pay attention to the contact between hour hand and minute hand.
Use the specified holding ring for dial to prevent rotation of the movement inside of the case in order to
stabilize the button operation.
Refer to the [Holding ring for dial] page instruction as to the shape and tolerance.
Use the metal case to prevent from the movement mal-function by static electricity.
Cal. YM04A Attention of casing part structure
31/Jul./'14
Rev. : 02
P.9

Date :
0 click 1st click
Crown Free Turn clockwise for date
change
2H button Chronograph Start/Stop
Restart
Chronograph Start/Stop
Restart
4H button
Chronograph Reset
Split
Split release
Chronograph Reset
Split
Split release
[*1] How to set the "0" position
Pull crown out to the 2nd click position.
↓
Press 2H button for 2 seconds.
↓
Press 4H button repeatedly to set it to "0" position.
↓
Press 2H button for 2 seconds.
↓
Press 4H button repeatedly to set it to "0" position.
↓
Push crown back to normal position.
Cal. Operation-01
31/Jul./'14
Rev. : 01
YM04A
Minute chronograph hand turns a full round and can now be
set to correct "0" position.
1/5 second chronograph hand turns a full round and can now
be set to correct "0" position.
[*1]
2nd click
Time setting
[*1]
Crown position
0 ® 1 ® 2
2H button
4H button
Minute hand
1/5 second chronograph hand
Minute chronograph hand
Crown
Hour hand
Small second hand
24 hour hand
P.10-01

Date :
Chronograph function
・The chronograph can measure up to 60 minutes in 1/5 second increments, capable of timing 12 hours.
・When the measurement reaches 12 hours, the chronograph automatically stops counting.
Standard measurement
Accumulated elapsed time measurement
Split time measurement
Cal. Operation-02
31/Jul./'14
Rev. : 01
YM04A
Start Stop Reset
2H button 2H button 4H button
Start Stop Restart
2H button 2H button 2H button 2H button 4H button
Start Split Split release
2H button 4H button 4H button 2H button 4H button
Stop Reset
ResetStop
Restart and stop of the chronograph
can be repeated by pressing 2H button.
Measurement and release of split time
can be repeated by pressing 4H button.
P.10-02