Seiko V157A User manual

PARTS LIST/TECHNICALGUIDE
ANALOGUE SOLAR Cal. V157A/V158A
[SPECIFICATIONS]
1/18
Item Cal. No. V157A/V158A
Power reserve
Driving system
Additional function
Crown operation
Loss/Gain
Regulation system
Number of jewels
Normal position
1st click position
Current consumption
Gate time for rate measurement
Power supply
Motion of the second hand
Coil resistance
Power
generator
Rechargeable
battery
Operating
voltage range
2nd click position
One-second intervals
Stepping motor 1 piece
Diameter
Outside: 28.6 mm
Casing: 24.0 mm
Height: 3.5mm
3 hands (hour, minute and second hands)
date indicator/day indicator(only for V158A)
Instart-start function
Energy depletion forewarning function (The second hand moves at
two-second intervals.)
Overcharge prevention function
Electronic circuit reset function
Second hand stop function
Date calendar
Instant setting device for date calendar
Day calendar (only for V158A)
Instant setting device for day calendar (only for V158A)
Free
Time setting
Monthly rate:less than 15 seconds (worn on the wrist at
temperature range between 5 to 35 degrees Centigrade)
Use 10-second gate
Nil
Solar power generation system
Movement: less than 0.80 μA
Circuit block: less than 0.40 μA
Coil block: 1.80 - 2.20 KΩ
MT920 Manganese titanium lithium rechargeable battery
0.45V - 2.20V
From full charge to stoppage: Approximately 10 months
2 jewels
V157A V158A
Date setting(counter clockwise)
Day setting (clockwise, only for V158A)
Movement

SPECIFICATIONS
2/18
Cal. V157A/V158A
FEATURES
The Cal. V157A/V158A are analogue watches with a solar power generation system.
l Solar power generation system
The watch operates while charging electricity by converting light received on the dial to
electrical energy. It lasts for 10 months after full charge.
l Energy depletion forewarning function
When the energy stored in the rechargeable battery is reduced to an extremely low level, the
second hand starts moving at 2-second intervals instead of the normal 1-second intervals.
l Instant-start function
When the watch is exposed to sunlight or strong artificial light (of more than 1,000 lux), it will
start operating immediately with the second hand moving at 2-second intervals.
l Guideline of charging time
Environment/Light source Illumination
(lux)
Time required
for full charge
Time required
for steady
operation
Time to charge
1 day of power
General offices/ Fluorescent
Light
700 - 25 hours 110 minutes
30W 20cm/Fluorescent light 3,000 120 hours 6 hours 30 minutes
30W 3cm/ Fluorescent light 10,000 35 hours 2 hours 10 minutes
Cloudy weather/Sunlight 10,000 35 hours 2 hours 10 minutes
Fair weather/Sunlight 100,000 9 hours 0.4 hours 2 minutes
The above table provides only a general guideline.
It is recommended that the watch be charged for as long as the charging time according to the
column "Time required for steady operation" in this table in order to assure the stable movement
of the watch.
l Caution for charging
When charging the watch, do not place it too close to a photo flash light, spotlight, incandescent
light or other light sources as the watch temperature will become extremely high, causing damage
to the parts inside the watch.
When exposing the watch to sunlight to charge it, do not leave it on the dashboard of a car, etc.
for a long time, as the watch temperature becomes extremely high.
While charging the watch, make sure the watch temperature does not exceed 60 °C.
V158A is a caliber which improved standard accuracy and power reserve from V145A, and also
available to be used for diver's watch.
V157A is a same caliber as V158A, but without a day calendar mechanism.

HOUR, MINUTE AND SECOND HANDS
DIAL
DIAL WASHER SPACER
0493 500
HOLDING RING FOR DIAL
2
3
1
SOLAR CELL
4025 581(V157A)
4025 580(V158A)
CONTACT SPRING FOR SOLAR CELL
4246524
DIAL WASHER
0491 735
SNAP FOR DAY STAR WITH
DIAL DISK
0963 230
DAY STAR WITH DIAL DISK
(ONLY FOR V158A)
INTERMEDIATE WHEEL FOR DAY
SETTING (ONLY FOR V158A)
0989 890
DATE JUMPER
0810 890 DATE SETTING WHEEL
0737 891
SECOND INTERMEDIATE
WHEEL FOR DATE SETTING
0962 891
HOUR WHEEL
0271 639
DATE DRIVING WHEEL
0802 890
4
5
6
9
7
8
DATE DIAL GUARD
0808 890
qa
DATE DIAL
qs
qf
qg
qh
qd
qj
PARTS LIST Cal. V157A/V158A
3/18
Please see the remarks on the following pages.
Order of disassembly: 1ra
Order of assembly: ra 1
Lubricating:
Types of oil Oil quantity
AO-3 Normal quantity
q;
AO-2

0022247
• BATTERY LEAD TERMINAL SCREW (1 PC.)
• CIRCUIT BLOCK COVER SCREW (2 PCS.)
• COIL BLOCK SCREW (1 PC.)
qk
ql
w;
wa
ws
wd
ra
Cal. V157A/V158A
PARTS LIST
4/18
Please see the remarks on the following pages.
CIRCUIT BLOCK COVER
4461522 (V157A)
4461520 (V158A)
RECHARGEABLE BATTERY UNIT
SCREW 0022247
RECHARGEABLE BATTERY UNIT
3023 24Y
CIRCUIT BLOCK COVER SCREW
0022247
CIRCUIT BLOCK
4000655
TRAIN WHEEL BRIDGE
0125907
wf FOURTH WHEEL AND PINION
0241559
wg THIRD WHEEL AND PINION
0231904
wh FIFTH WHEEL AND PINION
0701904
wj STEP ROTOR
4146907
wk MINUTE WHEEL
0261904
wl SETTING WHEEL
0281904
e; TRAIN WHEEL SETTING LEVER
0391890
COIL BLOCK SCREW
0022247
ea
ef SETTING LEVER
0383891
ek FIRST INTERMEDIATE WHEEL FOR
DATE SETTING
0962890
ej CLUTCH WHEEL
0282890
eh SETTING STEM
0351892
COIL BLOCK
4002907
es
eg YOKE
0384890
MAIN PLATE
0100576
r;
BATTERY CONNECTION (+)
4268655
el CENTER WHEEL AND PINION
0221602
ed
STATOR
4239907

PARTS LIST Cal. V157A/V158A
5/18
l How to find the correct parts, if not determined by 4 digit caliber number
Following parts are determined based on the design of watches, such as hands height, dial color,
and design of cases. Please refer to the SEIKO WATCH PARTS CATALOGUE in order to choose
corresponding parts.
4HOLDING RING FOR DIAL 0866855/0866861
The type of HOLDING RING FOR DIAL is determined based on the design of cases. Check the case
number and refer to the "SEIKO WATCH PARTS CATALOGUE" to choose corresponding HOLDING
RING FOR DIAL.
5SOLAR CELL 4025581 (for V157A) 4025580 (V158A)
9DAY STAR WITH DIAL DISK (only for V158A)
Parts number Position of crown
and calendar frame Language Color of figure Color of background
0160565 3 o’clock English/Spanish Black White
0160575 3 o’clock English/Spanish White Black
The DAY STAR WITH DIAL DISK used differs depending on the casing model. Refer to the parts code
number printed on the DAY STAR WITH DIAL DISK.
qs DATE DIAL
Parts number Position of crown
and calendar frame Color of figure Color of background
0878580 3 o’clock Black White
0878587 3 o’clock White Black
eh SETTING STEM 0351892
The type of SETTING STEM is determined based on the design of cases. Check the case number and
refer to the "SEIKO WATCH PARTS CATALOGUE" to choose corresponding SETTING STEM.
The type of DATE DIAL is determined based on the design of cases. Check the case number and refer
to the "SEIKO WATCH PARTS CATALOGUE" to choose corresponding DATE DIAL.

Cal. V157A/V158A
PARTS LIST
6/18
lTools and consumables required for disassembling/reassembling
•Movement holder
UNIVERSAL MOVEMENT HOLDER (S-682)
• Watch oils
SEIKO watch oils (AO-3 and AO-2)
AO-3 AO-2

TECHNICAL GUIDE Cal. V157A/V158A
7/18
REMARKS ON DISASSEMBLING AND REASSEMBLING
Crown position: normal position
Push the SETTING LEVER gently (refer to the Fig. 1) in order to disengage it from the SETTING STEM.
Then pull out the crown with the stem completely.
REMARKS ON DISASSEMBLING AND REASSEMBLING THE MOVEMENT
lHOW TO REMOVE THE SETTING STEM BEFORE DISMANTLING THE MOVEMENT
Place the movement directly on a flat metal
plate or the like to install the hands. In doing
so, check that the spring portion of the circuit
block cover is not pressed down.
Set the notched portions of the dial to the
guide posts (4 posts) of the HOLDING RING
FOR DIAL, and check that the dial is fixed
in position.
• How to install
1HANDS
Metal plate
• How to install
2DIAL
Dial
Guide posts
Guide posts
Fig. 1

９H
12H
３H
６H
TECHNICAL GUIDE Cal. V157A/V158A
8/18
4HOLDING RING FOR DIAL
• Disassembling
1. The HOLDING RING FOR DIAL is fixed by 4 hooking portions.
2. Insert the tip of a screwdriver into the gap between the hooking portion and main plate as shown
in the illustration, and then turn the screwdriver in the direction of the arrow to release the hooking
portion from the main plate.
* It is not necessary to remove the SOLAR CELL from the HOLDING RING FOR DIAL.
• Reassembling
1. Set the 4 hooking portions as shown in the illustration.
2. Gently push the HOLDING RING FOR DIAL above the
hooking portions so that they catch the main plate
securely.
• When installing the HOLDING RING FOR DIAL, take care
not to damage or deform it.
• After installing the HOLDING RING FOR DIAL, check that all
hooking portions catch the main plate secuirely.
Notes:
• Disassembling and Reassembling of HOLDING RING FOR DIAL and SOLAR
CELL
* It is not necessary to disassemble HOLDING RING FOR DIAL
and SOLAR CELL except in the case that a part needs to be
replaced.
<Disassembling>
As there are hooking portions at 12 o'clock and 6 o'clock
sides, release them side by side.
<Assembling>
Gently push the SOLAR CELL at 12 o'clock and 6 o'clock
sides.
6CONTACT SPRING FOR SOLAR CELL
Assemble the one side of spring to the main plate as
shown in the illustration (white arrow), and then set the
other side as shown in the illustration (black arrow)

TECHNICAL GUIDE Cal. V157A/V158A
9/18
q; INTERMEDIATE WHEEL FOR DAY SETTING (only for V158A)
Please take care of the assembling direction of
INTERMEDIATE WHEEL FOR DAY SETTING.
qa DATE DIAL GUARD
For the Cal. V157A and V158A, new assembling
construction with 3 hooking portions and 2 guide
pins are used.
• Disassembling
1. Remove the DATE DIAL GUARD from guide
pin of A part by the tweezers as shown in the
illustration, and turn the DATE DIAL GUARD
counter-clockwise until it goes on to the guide
pin.
2. Remove the DATE DIAL GUARD from guide pin
of B part the same as A part.
3. After confirming that the 3 hooking portions
on the main plate are removed from the DATE
DIAL GUARD, remove it from main plate.
• Assembling
1. Put the DATE DIAL GUARDonthepostion which
is shown in the illustration. Please put A and
B parts on the guide pins.
2. Set the hooking portion of D part to the main
plate by turning it clockwise.
3. Set the hooking portions of C and E part, and
set A and B parts to the guide pins at the same
time.
4. Check if the DATE DIAL GUARD is properly
assebmled to the main plate.
A part
hooking portions
B Part

TECHNICAL GUIDE Cal. V157A/V158A
10/18
ql RECHARGEABLE BATTERY UNIT
• How to remove
Remove the battery lead terminal screw, and then
pry up the “A” portion in the illustration with tweezers
to remove the rechargeable battery unit.
• How to install
Set the “B” portion of the battery lead terminal to the
guide hole of the main plate, and then push the center
portion of the rechargeable battery unit (the “C”
portion in the illustration) to fix it in position.
Battery lead terminal
Notes:
• Be sure to observe the correct polarity of the
rechargeable battery unit. The (-) side has the lead
terminal.
• Handle the rechargeable battery unit with care so
as not to short-circuit its (+) and (-) terminals.
“C” portion
Rechargeable battery unit
wd TRAIN WHEEL BRIDGE
Fourth wheel and pinion
Minute wheel
Refer to the illustrations below to check where to install the respective wheels.
Step rotor
Third wheel and pinion
Setting wheel
Fifth wheel and pinion
Step rotor
Fourth wheel and pinion
Fifth wheel and pinion Third wheel and pinion
Minute wheel
Setting wheel
e; TRAIN WHEEL SETTING LEVER
ef SETTING LEVER
eg YOKE
• Setting position
Refer to the illustration at right.
Setting lever
• Setting position
Yoke
Train wheel setting lever
Center wheel and pinion
“B” portion
“A” portion
The date corrector wheel has some elasticity
in the contact with the winding stem so that
it can be easily fixed.
Push in the winding stem straight toward
the center of the main plate.
eh SETTING STEM
Winding stem
Date corrector wheel
Clutch wheel

TECHNICAL GUIDE Cal. V157A/V158A
11/18
l CHECKING THE ELECTRICAL CHARACTERISTICS
<Coil resistance>
es COIL BLOCK between 1.80 and 2.20 kΩ.
<How to measure the current consumption for the whole movement>
1) Remove the 5SOLAR CELL and the ql RECHARGEABLE BATTERY UNIT from the movement.
2) Tighten the qk RECHARGEABLE BATTERY UNIT SCREW.
3) Connect the (-) probe to the (-) input terminal of the qk RECHARGEABLE BATTERY UNIT SCREW and
(+) probe to the r; BATTERY CONNECTION (+) as illustrated in Fig. 2.
* When measuring the current consumption using
the SEIKO digital multi-tester (S-860), use the
range of 40μA of SUPPLY V (=1.55V) & GATE
TIME (2S).
3) Wait until a stable measurement becomes available. It usually takes 30 seconds to a few minutes
for getting a stable measurement.
4) Make sure that the read value is less than 0.80μA.
REMARKS ON INSPECTION AND MEASUREMENT
BATTERY CONNECTION (+)
Fig. 2
RECHARGEABLE BATTERY UNIT SCREW

TECHNICAL GUIDE Cal. V157A/V158A
12/18
* When measuring the current consumption using
the SEIKO digital multi-tester (S-860), use the
range of 40μA of SUPPLY V (=1.55V) & GATE
TIME (2S).
* Avoid exposingtheCIRCUIT BLOCKtodirectlight
in order to obtain the correct measurement.
2) Wait until a stable measurement becomes available. It usually takes 30 seconds to a few minutes
for getting a stable measurement.
3) Make sure that the read value is less than 0.40μA.
Note:
In case the measurement of the current consumption for a whole movement exceeds the standard
value but the measurement for the circuit falls below the standard value, a problem in the gear train
mechanism is suspected. Please disassemble and overhaul the movement and measure the current
again.
<How to measure the current consumption for the CIRCUIT BLOCK alone>
1) Connect each probe to the appropriate (-) and (+) input terminal of the ws CIRCUIT BLOCK (please
refer to the "Structure of the CIRCUIT BLOCK" below).
[Structure of the CIRCUIT BLOCK]
Solar cell input terminal (-)
Input terminal (+) (Also serves as a solar cell input terminal
Input terminal (-)
C-MOS-IC
Crystal
Coil output terminal

TECHNICAL GUIDE Cal. V157A/V158A
13/18
FLUORESCENT LAMP
l CHECKING THE SOLAR POWER GENERATION SYSTEM
<How to check the solar power generation with the watch>
1) Remove the ql RECHARGEABLE BATTERY UNIT from
the watch.
2) Pull out the crown to the 2nd click in order to reset the
circuit.
3) Connect the (-) probe to the (-) input terminal for the 5
SOLAR CELL and (+) probe to the wa CIRCUIT BLOCK
COVER (as illustrated in Fig. 3).
* When measuring the voltage using the SEIKO digital
multi-tester (S-860), use the range of V (Fig. 4).
4) Expose the watch to the light of a fluorescent lamp
(use the one with 15 to 20 watts) at a distance of 5 cm
while connecting the probes to the watch (Fig. 5).
5) Read the measurement and check if it exceeds 1.8 V.
5 cm
Fig. 4
Fig. 5
Fig. 3

TECHNICAL GUIDE Cal. V157A/V158A
14/18
Note: In case the measurement of the voltage for the watch does not achieve the standard value but
the measurement for the solar cell unit alone exceeds the standard value, a problem in the electrical
conductivity between the solar cell unit and the movement is suspected. Inspect the electrical
conductivity, especially at the CONTACT SPRING FOR SOLAR CELL, and check the solar power
generation system again.
<How to check the solar power generation with the SOLAR CELL alone>
1) Set the DIAL to the HOLDING RING FOR DIAL.
2) Connect the tester as the below illustration.
* When measuring the voltage using the SEIKO digital
multi-tester (S-860), use the range of V (Fig. 6.)
2) Expose the SOLAR CELL to the light of a fluorescent lamp (use the one with 15 to 20 watts) at a
distance of 5 cm while connecting the probes to the solar cell unit (Fig. 7.)
3) Read the measurement and check if it exceeds 1.8 V.
Fig. 6
Fig. 7
5 cm
FLUORESCENT LAMP
15 - 20 W

TECHNICAL GUIDE Cal. V157A/V158A
15/18
l CHECKING THE INSTANT-START FUNCTION
The instant-start function works when the voltage of the rechargeable battery is more than 0.9V.
Therefore, please measure the battery voltage and make sure that the battery is ready for checking
the instant-start function.
* When measuring the voltage of the rechargeable
battery, connect the (-) probe to the RECHARGEABLE
BATTERY UNIT SCREW and (+) probe to the wa CIRCUIT
BLOCK COVER as illustrated in Fig. 8.
<How to check the instant-start function>
1) Place the watch which stops working at a distance of
50 cm under the fluorescent lamp of 15 to 20 watts
(Fig. 9.)
2) Check if the second hand of the watch starts moving
at 2-second intervals within 10 seconds.
+
‒
FLUORESCENT LAMP
50 cm
Fig. 9
Fig. 8

TECHNICAL GUIDE Cal. V157A/V158A
16/18
l CHECKING THE RECHARGING FUNCTION
In order to check the recharging function, measure the voltage of the rechargeable battery before and
after recharging. If the voltage increases to a certain extent, it shows that the recharging function is
working properly.
1) Measure the voltage of the rechargeable battery before recharging (please refer to Fig. 8 of
page 15 for where to apply the probes of the tester).
2) Recharge the watch by placing it at a distance of 5 cm under the fluorescent lamp of 15 to 20
watts for 30 minutes (Fig. 10.)
FLUORESCENT LAMP
5 cm 5 cm
FLUORESCENT LAMP
Fig. 11
Fig. 10
3) Measure the voltage again while keeping the watch exposed to the light (Fig. 11.)
4) Compare the difference of the voltage before and after recharging. Refer to the table
below for the criteria of the inspection.
0.50V - 1.00V
Results after recharging and criteria for checking the function
Recharging function works fine
The voltage
BEFORE recharging
1.01V - 1.30V
Less than 1.09V
Increased by 0.03V or more
More than 1.10V
Not increased or increased
but not more than by 0.03V
The battery needs to be inspected and
replaced if necessary
Table - criteria recharging function Cal. V157A/V158A

TECHNICAL GUIDE Cal. V157A/V158A
17/18
l FUNCTION CHECK
Operation Function Checkpoint
Pull out the
crown to the 2nd
click and push
it back in to the
normal position.
Repeat the same
several times.
Setting mechanism
switching the func-
tion of the time set-
ting.
Make sure that it has
a click at each posi-
tion and the stem is
not pulled off.
Pull out the
crown to the 1st
click, then turn it
clockwise.
Calendar mechanism
- correcting the day.
Ma ke sure that the
day changes smooth-
ly.
Pull out the
crown to the 1st
click, then turn it
Calendar mechanism
- correcting the date.
Ma ke sure that the
date changes smooth-
ly.
Sec o nd h an d s to p
function.
Ma ke sure that the
second h and s tops
whe n the c row n is
pulled out to the 2nd
click.
Set ting mechanism
- hou r and minu t e
hand setting.
Make sure that the
hour and minute
hands move
smoothly (without
touching each other
or touching the
surface of the dial or
inside of the glass).
Hands installation.
calendar mechanism
- date change.
Ma ke sure that the
date changes when
the hour and minute
hands pa ss around
midnight.
MON
MON 6
Pull out the
crown to the
2nd click, then
turn it.

TECHNICAL GUIDE Cal. V157A/V158A
18/18
l CHECKING THE WATER RESISTANCE
l CHECKING THE ACCURACY - INSTANTANEOUS RATE
Measure the rate and make sure the value shows within ±0.50 s/d.
Use 10-second gate of the tester.
Marking on the case back Test method Applied pressure
WATER RESISTANT (WATER RESIST) 3 BAR
WATER RESIST 5BAR 5 BAR
WATER RESIST 10BAR 10 BAR
WATER RESIST 15BAR 15 BAR
WATER RESIST 20BAR 20 BAR
SCUBA DIVER'S (AIR DIVER'S) 150 m 18.75 BAR = 150 (m) times 0.125
SCUBA DIVER'S (AIR DIVER'S) 200 m 25 BAR = 200 (m) times 0.125
He-GAS DIVER'S 300 m 37.5 BAR = 300 (m) times 0.125
He-GAS DIVER'S 600 m 75 BAR = 600 (m) times 0.125
He-GAS DIVER'S 1000 m 125 BAR = 1000 (m) times 0.125
Water pressure test
Condensation test
Condensation test
Condensation test
Water pressure test
Air leak test
Check the water resistance according to the designated specification of the watch.
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