Seiko W850A, W851A, W854A, W853A Technical Manual
1
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]
2
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
3
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
Electroluminescent
panel
22 4246 085
Electroluminescent
lead terminal
23 4512 044
Liquid crystal
panel frame
4
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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