Seiko W850A Quick start guide

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PARTS CATALOGUE /TECHNICAL GUIDE
Cal. W850A, W851A
Cal. W853A, W854A
Cal. No.
Item W850A, W851A, W853A, W854A
(x 1.0)The illustrations refer to Cal. W853A.
Module
Module size Outside diameter ø29.0 mm
–Casing diameter
Height 6.0 mm (Including the battery portion)
Display medium Nematic Liquid Crystal, FEM (Field Effect Mode)
Liquid crystal driving system Multiplex driving system
Display system • Time/calendar display
• Stopwatch display (Up to 9 hours, 59 minutes and 59.99 seconds in
1/100 seconds)
• Alarm display (5-channel daily alarm)
• Timer display (Two types of countdown timer: Preset timer with 10
preset times and 10-hour adjustable timer)
• World time display (38 cities)
Additional mechanism • Selection of a desired mode in the menu display
• Changeover between the normal and enlarged displays
• Quick digits moving function
• Graphic display, scroll display and motion graphic demonstration
function
• Auto illumination function
• Electroluminescent panel
• Battery life indicator
• Sound demonstration
• Changeover between 12- and 24-hour indications
Loss/gain Monthly rate at normal temperature range: less than 20 seconds
Regulation system Nil
Measuring gate by quartz tester Any gate can be used.
Battery SEIKO CR2025, Sony CR2025, Matsushita CR2025
Battery life is approximately 2 years.
Voltage: 3.0 V
[SPECIFICATIONS]

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PARTS CATALOGUE Cal. W850A, W851A, W853A, W854A
Disassembling procedures Figs. : 1 →23
Reassembling procedures Figs. : 23 →1
Lubricating: Types of oil Oil quantity
Silicone oil 500,000 Normal quantity
➡Please see the remarks on the following pages.
Button A
Button B
Button C
Button D
Button E
Button F
Button spring clip
7 Conductive plate for the front button
6 Conductive plate for the side button
5 Module
3 Case back gasket
1 Case back screw
4589 024
Piezoelectric element
2 Case back
4 4246 066
Buzzer lead terminal

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PARTS CATALOGUE
➡Please see the remarks on the following pages.
(Reversed battery guard)
(Reversed liquid crystal panel frame)
19 4313 137
Connector
Cal. W850A, W851A, W853A, W854A
8 0110 196 (Cal. W850A)
0110 197 (Cal. W851A)
0110 211 (Cal. W853A)
0110 132 (Cal. W854A)
Sticker
10 Battery
(See the front page.)
9 4225 098
Battery clamp
11 Switch spring (A)
12 4395 046
Battery guard
13 4408 068
Spacer for switch spring (B)
14 4245 235
Switch spring (B)
15 4290 036
Rubber switch
16 4270 118
Battery connection (–)
17 4271 333
Battery connection (+)
18 4003 306 (Cal. W850A)
4003 307 (Cal. W851A)
4003 309 (Cal. W853A)
4003 310 (Cal. W854A)
Circuit block
20 4510 394 (Cal. W850A, W851A)
4510 364 (W851A)
4510 402 (Cal. W853A, W854A)
Liquid crystal panel
21 4536 025
Electro-
luminescent
panel
22 4246 085
Electro-
luminescent
lead terminal
23 4512 044
Liquid crystal
panel frame

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Remarks:
PARTS CATALOGUE Cal. W850A, W851A, W853A, W854A
•Conductive spring
Some models use a conductive spring as a casing part. Check the case number and refer to “SEIKO Parts
Catalogue”.
20 Liquid crystal panel
The type of liquid crystal panel is determined based on the design of cases. Check the case number and
refer to “SEIKO Parts Catalogue” to choose a corresponding liquid crystal panel.
TECHNICAL GUIDE
•The explanation here is only for the particular points of Cal. W850A, W851A, W853A and W854A.
•For the repairing, checking and measuring procedures, refer to the “TECHNICAL GUIDE, GENERAL
INSTRUCTIONS”.
I. STRUCTURE OF THE CIRCUIT BLOCK
II. REMARKS ON INSTALLING THE BATTERY
After the battery is replaced with a new one, or after the battery is re-installed following the repairing
procedures, be sure to follow either of the two methods below to reset the circuit.
•METHOD 1
To reset the circuit of a module:
Short-circuit the AC terminal of the circuit block and the
battery positive surface with conductive tweezers as
illustrated at right.
Cal. W850A, W851A, W853A, W854A
Input terminal (+) Input terminal (–)
Crystal unit
C-MOS-IC
Tweezers
AC terminal
Battery (+) side

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TECHNICAL GUIDE Cal. W850A, W851A, W853A, W854A
•METHOD 2
To reset the circuit of a complete watch:
Press and hold buttons “A”, “B”, “C” and “E” at the
same time for 2 to 3 seconds.
* The display will become blank, indicating that the
circuit is reset. Then, the display will return to the
MENU display.
* After resetting the circuit, be sure to set the time/
calendar again as the time/calendar data returns
to the initial settings.
Button C
Button A
Button B
Button E
III. REMARKS ON DISASSEMBLING AND REASSEMBLING
•Piezoelectric element 4589 024
The piezoelectric element, which is adhered to the case back, is available for supply separately from the
case back.
Use the universal movement holder for disassembling and reassembling.
4 Buzzer lead terminal
•How to remove
Turn the buzzer lead terminal to release its end
portion from the groove of the battery guard,
and then remove it.
•How to install
Set the end portion of the buzzer lead terminal
into the groove of the battery guard, and then
turn it to fix it.
➡
End portion of the
buzzer lead terminal
6 Conductive plate for the side button
7 Conductive plate for the front button
•How to install
• Insert the conductive plates for the side and front buttons into the gap between the button spring
clip and the case middle as shown in the illustrations on the next page.

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TECHNICAL GUIDE Cal. W850A, W851A, W853A, W854A
Conductive plate Case middle Conductive plate for the side button Conductive plate for the front button
Button spring clip Case back
Conductive plate
• When closing the case back, check that the
conductive plates are in contact with the case back,
being bent by it towards the center of the watch.
• In doing so, the case back may be hard to set in
position, as the conductive plates have a repelling
force when bent.
9 Battery clamp
•How to remove
Insert the tip of tweezers into the protrusion of the
hooking portion of the battery clamp and pry it up
toward the direction of the arrow in the illustration at
right to remove it.
Tweezers
Battery clamp
10 Battery
•How to install
Set the battery in the direction of the arrow with its
(–) side down.
11 Switch spring (A)
•How to remove
Release the four hooking portions of the switch spring (A) indicated by the arrows in the illustration
on the next page, and then, lift it up to remove.
•How to install
Set the switch spring (A) to the guide posts “a” and “b” in the illustration on the next page, and then,
have the four hooking portions of the switch spring catch the module securely.

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TECHNICAL GUIDE Cal. W850A, W851A, W853A, W854A
a
b
• Do not disassemble the switch spring (B) and its spacer except when they need to be replaced.
• When installing the spacer for switch spring (B), take care not to set it in the wrong direction. (See
the exploded view on page 3.)
13 Spacer for switch spring (B)
14 Switch spring (B)
[ How to release the hooking portion ]
15 Rubber switch
16 Battery connection (–)
17 Battery connection (+)
18 Circuit block
•How to install
First, set the rubber switch, battery connection (–) and battery connection (+) to the circuit block in
the positions as indicated in the illustration below. Then, install the battery guard from above to fix
them securely to the movement. In doing so, take care lest the switch and connections should get
out of position.
Battery connection (–)Battery connection (+)
Rubber switch

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TECHNICAL GUIDE Cal. W850A, W851A, W853A, W854A
•How to install
Set the end portion of smaller diameter to the guide
hole of the liquid crystal panel frame.
22 Electroluminescent lead terminal
Liquid crystal
panel frame
Electroluminescent
lead terminal
23 Liquid crystal panel frame
•How to remove
Release the hooking portion of the liquid crystal panel
frame (“A” portion in the illustration at right) by
moving it in the direction of the arrow with the tip of
tweezers, and remove the liquid crystal panel.
•How to install
Slip the liquid crystal panel into the gap under “B”
portion of the liquid crystal panel frame, release “A”
portion by moving it in the direction of the arrow with
the tip of tweezers, and then, set the liquid crystal
panel.
20 Liquid crystal panel
“A” portion Liquid crystal panel
“B” portion
IV. VALUE CHECKING
•Current consumption
For the whole module : Less than 9.4 µA (with voltage of 3.0 V supplied from a battery)
For the circuit block alone : Less than 5.5 µA (with voltage of 3.0 V supplied from a battery)
•All the segments lit up
How to light up all the segments
In the TIME/CALENDAR mode, press and hold button “B” for 2 to 3 seconds to show the TIME/CALENDAR
SETTING display, and then, press buttons “C” and “D” at the same time to light up all the segments of the
display.
•With all the segments lit up, check for abnormal displays, etc.
•To return to the normal display, press button “A”, “B”, “C”, “D”, “E” or “F”. (The watch will return to
the TIME/CALENDAR mode.)
(Correction: Current consumption 2009.01.21 )

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TECHNICAL GUIDE Cal. W850A, W851A, W853A, W854A
•Time accuracy
1) Light up all the segments of the display, following the procedure above.
2) Place the watch on the microphone’s mark for placing the watch with the liquid crystal panel facing
the mark.
* If a stable measurement cannot be obtained, adjust the level by turning the level adjuster knob.

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HOW TO USE
•The functions and operation of the buttons are listed below. For checking or repair of the watch, refer to
the table below for guidance.
Cal. W850A, W851A, W853A, W854A
Button C
Button A
Button B
Button D
Button E
Button F
Turning on the
electroluminescent
light
Button F
One press:
Scrolling the
name of the
selected city
Continuous
press for 2 to 3
seconds:
Displaying the
city name, and
then, activating
the demonstra-
tion function
Button E
Changeover bet-
ween the normal
and enlarged
displays
Button D
–
Button C
TIME/
CALENDAR
SETTING
function by
pressing for 2 to
3 seconds
Button B
Returning to the
MENU display
Button A
In the MENU
display
In the selected mode
Press button
“A” to show
the TIME/
CALENDAR
mode.
Turning on the
electroluminescent
light
Selection of the
desired alarm
channel (from
channel 1 to 5)
Changeover bet-
ween the normal
and enlarged
displays
Engagement/
disengagement
of the alarm
ALARM
SETTING
function by
pressing for 2 to
3 seconds
Returning to the
MENU display
Press button
“B” to show
the ALARM
mode.
Turning on the
electroluminescent
light
Resetting the
stopwatch
Changeover bet-
ween the normal
and enlarged
displays
Start/stop of the
stopwatch
MEMORY
RECALL
function
Returning to the
MENU display
Press button
“C”toshowthe
STOPWATCH
mode.
Turning on the
electroluminescent
light
Resetting the
timer
Selection of the
preset time
Changeover bet-
ween the normal
and enlarged
displays
Start/stop of the
timer
ADJUSTABLE
TIMER SETTING
function by
pressing for 2 to
3 seconds
Returning to the
MENU display
Press button
“D” to show
the TIMER
mode.
Turning on the
electroluminescent
light
Selection of
cities
Changeover bet-
ween the normal
and enlarged
displays
Selection of
cities
Changeover
between the
standard time
and daylight
saving time
Returning to the
MENU display
Press button
“E” to show
the WORLD
TIME mode.
––––––Press button
“F” to
illuminate the
display.
* By pressing the corresponding button in the MENU display, a desired mode can be selected as shown in the
table above.
* The table above covers the basic button operations of the watch only. Use it for the checking after repair.

99-10 Printed in Japan