Seiko 8T68A Installer manual

PARTS CATALOGUE / TECHNICAL GUIDE
Cal.8T68A
8T68A
Driving system Step motor 2 pieces
Additional function
Crown Normal position Free
operation 1st click position Date setting (clockwise)
2nd click position Time setting, Resetting the circuit
Loss/Gain (Monthly rate) Less than 15 seconds at normal temperature range
Frequency of crystal oscillator 32,768 Hz
Operational temperature range
-5℃~ +50℃
Regulation system Nil
Gate time for rate measurement Use 10-second gate
Current consumption
Coil resistance
・4002054（Coil block A): 1.45 - 1.65KΩ
・4002055（Coil block B): 1.65 - 1.85KΩ
Power Battery No.
SR936SW (Silver oxide battery)
supply Battery voltage
1.55V
Battery life Approximately 3 years
Jewels
0 jewel
1/19
Cal. No.
Item
・Stopwatch function up to 60 minutes in 1/5 second
・Date display with quick correction.
・Energy depletion forwarding function
(The second hand moves at two-second intervals.)
・Movement: Less than 2.7μA
・Circuit block: Less than 0.7μA
Movement Size
・Outside diameter: 30.8 mm
・Casing diameter 29.0 mm
・Height：5.1 mm
・3 Hands: Hour, Minute, and 1/5 second chronograph hand
・Small Second : Small second hand(6H), Minute chronograph hand (10H),
and 24-hour indicator(2H)

PARTS CATALOGUE
8T68A
Type of oil
Oil quantity mark
AO-3(Moebius A）NORMAL QUANTITY
AO-2(Moebius F)
SUFFICIENT QUANTITY
S-6
0012 354
Date indicator maintaining plate screw
0808 052
Date indicator maintaining plate
Date indicator
0810 019
Date jumper
0806 002
Date corrector wheel
[ Cross section ]
2/19
4
5
6
Intermediate small hour hand wheel and pinion
0817 048
1
2
Small hour hand wheel
7
0157 013
3
Refer to page 8 for each parts code.
Disassembling procedures Figs.
1
→
60
Reassembling procedures Figs.
60
→
1
*1
*1

PARTS CATALOGUE 8T68A
0273 042
Hour wheel
0012 354
Switch lever holder screw
0837 007
Switch lever holder
4450 018
4450 017
Switch lever B Switch lever A
Refer to page 12 for Refer to page 12 for
setting position. setting position.
0962 891
0962 013
3/19
14
Date corrector setting
transmission wheel C
13
Date corrector setting
transmission wheel B
8
9
10
11
12
*1
*1

PARTS CATALOGUE 8T68A
0016 121
0016 121
Switch spring screw
Switch spring screw
4250 095
Switch spring
Refer to page 12 for
spring setting position.
0353 018
0190 009
Chronograph bridge
0581 007
0587 008
Chronograph
coupling lever
Refer to page 12 for Refer to page 12 for
spring setting position. spring setting position.
0585 015
0894 002
Hammer Train wheel stop lever
Refer to page 10 for Refer to page 12 for
oiling spot and page 12 spring setting position.
for spring setting position.
0888 029
0587 004
Hammer operating lever A
0902 018
Refer to page 12 for
Minute counting spring setting position.
wheel
4/19
Seconds counting
wheel
Seconds counting wheel
friction spring
20
Hammer operating lever B
21
19
22
16
17
24
25
15
15
23
18
*1
*2
*1
*2

PARTS CATALOGUE 8T68A
0016 121
0186 004
Lower plate for chronograph bridge
Refer to page 10 for
oiling spot.
4408 149
Circuit block spacer
0125 319
4004 353
Train wheel bridge Circuit block
*㉜～㊱
Refer to page 9 for assembling
of chronograph wheel.
4270 336
Battery connection (-)
0012 354
Coil block screw
4002 054
0885 003* Coil block A
4146 063
Step rotor
0886 004*
4239 063
Stator A
0886 005*
0701 015
Fifth wheel and pinion
5/16
38
39
40
41
34
Minute counter intermediate
wheel and pinion A
Counter intermediate
wheel and pinion
Seconds counter
intermediate
wheel and pinion
37
35
36
30
27
Lower plate for chronograph bridge screw
0886 007*
Minute counter intermediate
wheel C
31
32
33
0886 006*
Minute counter intermediate
wheel B
26
28
29

PARTS CATALOGUE 8T68A
0231 059
4455 006
Third wheel and pinion
Reset lever
0144 002
0391 028
Fourth wheel and pinion Train wheel setting lever
0261 126
Minute wheel and pinion
0281 452
0012 354
Setting wheel
Coil block screw
4283 042
4002 055
Coil block B
4146 063
Step rotor
0221 092
4239 064
Stator B
0383 891
0701 015
0384 024
Yoke
0240 019
Seconds wheel
0282 452
Clutch wheel
0962 032
0351 177
Winding stem
6/19
58
55
60
59
Date corrector
setting transmission
wheel A
57
Center wheel and
pinion bridge
48
54
Fifth wheel and
Center wheel and
pinion
56
Setting lever
44
45
42
49
pinion
52
53
51
47
50
46
43
*1
*1

PARTS CATALOGUE 8T68A
●Tools and consumables required for disassembling/reassembling
・Movement Holder
UNIVERSAL MOVEMENT HOLDER (S-682)
・Waich oils
SEIKO watch oil AO-2, AO-3 and S-6
AO-2 AO-3
S-6
7/19

TECHNICAL GUIDE 8T68A
Remarks:
Date indicator
* All parts code are subject to change without notice.
8/19
Color of
background
3H
Black
0878 329
3H
White
0878 328
4.5H
●
Parts code
Crown
position
Date
position
Color of figure
Black
4.5H
White

TECHNICAL GUIDE 8T68A
●How to assemble chronograph wheel
There is a mark on parts. Parts are set in order of the mark as shown in the table below.
Image example of the mark
0886 007
0886 006
0885 003
0886 004
0886 005
*Mark positions, and sizes, etc. are different.
9/19
Counter intermediate
wheel and pinion
36
Minute counter intermediate
wheel and pinion A
35
32
Minute counter intermediate
wheel B
Seconds counter intermediate
wheel and pinion
Minute counter intermediate
wheel C
33
34
G
32
Minute counter intermediate wheel C
F
33
Minute counter intermediate wheel B
Nil
34
Seconds counter intermediate wheel and pinion
C
35
Counter intermediate wheel and pinion
Mark
Parts name
B
36
Minute counter intermediate wheel and pinion A
REMARKS ON DISASSEMBLING AND REASSEMBLING THE MOVEMENT

TECHNICAL GUIDE
8T68A
Type of oil Oil quantity mark
AO-3(Moebius A）
NORMAL QUANTITY
AO-2(Moebius F) SUFFICIENT QUANTITY
S-6
●Remarks for the lubrication
Hammer
Note:
There must be oil within the range of the arrow.
Lower plate for chronograph bridge
Note:
*1: Lubricate on the pointed spot.
16 Switch spring
Oiling spot and spring setting position are below;
Chronograph coupling lever Hammer operating lever B
Setting position
Switch spring
10/19
16
*Lubricate on the contact spot of the spring and the pin.
21
19
20
27
*1
*1
*2
*3
*2
*3
*1
*1

TECHNICAL GUIDE 8T68A
●How to remove the Winding Stem
1) Set the winding stem to normal position (=0).
2) Pull out the Crown with winding stem,
while pushing "A" carefully.Push "A"
●How to remove or install the Battery
1) Remove the hook of the Switch Spring's Battery Clamp as illustrated in the drawing 1).
2) Insert the battery sideways as illustrated in the drawing 2) , and have the hook of
the Switch Spring's Battery Clamp catch the main plate.
Switch spring
Battery clamp
1) Removing Main plate 2) Installing
●Remarks on installing the Battery
After replacing the battery with a new one,
or reinstalling, be sure to touch the AC Tweezers
terminal of circuit block and the switch spring
with conductive tweezers to reset the circuit
as illustrated.
11/19
16

TECHNICAL GUIDE 8T68A
3.Spring setting position Train wheel stop lever
Lower plate for chronograph bridge
Hammer operating lever A
Hammer
Hammer operating lever B Chronograph coupling lever
4.Switch lever A and B setting position
Switch spring
Switch spring
Switch lever BSwitch lever A
Hammer operating lever A
Chronograph coupling lever
12/19
Setting position
19
Switch lever B is set between the
switch spring and hammer operating lever A .
Switch lever A is set between the
switch spring and chronograph coupling lever.
16
16
12
11
25
24
27
25
21
20
19
*4
*1
*2
*3
*1
*2
Enlarged view
*1
*2
*1
*2
*3
*4

TECHNICAL GUIDE 8T68A
●How to measure the current consumption for the whole movement
1. To measure the current consumption for the whole move-
ment, connect the (-) probe to the battery connection (-)
and (+) probe to the other metal part of the movement,
such as battery clamp or circuit block cover.
*When measuring the current consumption using the
SEIKO digital multi-tester (S-860), use the range of
40 μ A of SUPPLY V (= 1.55 V) & GATE TIME (2 S).
2.
Connect the AC component to the positive terminal for 2
seconds until a short circuit occurs to reset the integrated
circuit.
3. After the integrated circuit is reset, wait approximately for
10 seconds until a stable measurement is obtained, and
then read the measurement.
4. Make sure the read value is less than 2.7 μ A.
●How to measure the current consumption for the CIRCUIT BLOCK alone
1. To measure the current consumption for the CIRCUIT BLOCK
alone, connect each probe to the appropriate positive (+) or
negative ( - ) input terminal of the CIRCUIT BLOCK
(please refer to “Structure of the CIRCUIT BLOCK” ).
*When measuring the current consumption using the SEIKO
Multi-Tester S-860, use the range of 4 μ A of SUPPLY
V (= 1.55 V) & GATE TIME (2 S).
2. Repeat the same procedures as 2. and 3. of measuring
current consumption for the whole movement above.
*
When measuring the current consumption for the circuit
block alone, be careful not to damage or deform the pattern
of the circuit block.
3. Make sure the read value is less than 0.7 μ A.
13/19
REMARKS ON INSPECTION AND MEASUREMENT

TECHNICAL GUIDE 8T68A
〔STRUCTURE OF THE CIRCUIT BLOCK〕
●Value checking -coil reistance (coil block)
Check the resistance of each coil block if they are within the range in the following table.
COIL BLOCK (A) 4002054 1.45 - 1.65KΩ
COIL BLOCK (B) 4002055 1.65 - 1.85KΩ
14/19
Output terminal
(Hand moving)
Crystal unit
C-MOC-IC
Input terminal
Output terminal
(CG)
Input terminal (-)

TECHNICAL GUIDE 8T68A
*2
*3 *7
*1 *9
*11
*10
*5 *8
*4 *6
Note
1.How to set the time
1) Pull out the crown to the second click position.
2) Turn the crown to set hour and minute hands.
(Check that AM / PM is set correctly.)
3) Push the crown back into the normal position.
[ Note ]
2.How to set the date
1) Pull out the crown to the first click position.
2) Turn the crown clockwise for date setting.
*Do not set the date between 9:00 P.M. and 3:00 A.M. as this will cause a malfunction.
3) Push the crown back into the normal position.
3.How to reset (after battery change)
It is possible to reset by the following two methods.
1) Set the crown to the normal position.
Method 1
2) Touch the AC terminal of circuit block and the switch spring with conductive tweezers
to reset the circuit.
3) The small second hand will move at two-second interval for 10 seconds.
1) Pull out the crown to the second click position.
Method 2
2) Press the button B for two seconds and release the button.
3) Push the crown back to the normal position.
4) The small second hand will move at two-second interval for 10 seconds.
* If the crown is operated within this 10 seconds, the two-second interval movement will not activate.
[ Note ]
It is not necessary to set the chronograph hands after the battery is exchanged.
If the chronograph hands position are incorrect, following below procedure all the chronograph hands
will be reset to "0" position.
15/19
Button A
(START)
Button A
(STOP)
Button B
(RESET)
If the crown is pulled to the second position while the chronograph is started, the chronograph hands
will continue to move. This is not a malfunction.
*5:
Chronograph minute hand
(60 minute)
*10:
Crown at first position
(Date setting)
DISPLAY AND CROWN / BUTTON OPERATION
*1:
Hour hand
*6:
24 hour hand
*11:
Crown at second position
(Time setting)
*4:
Small second hand
*7:
*8:
Button B (RESET)
*9:
Crown at normal position
Button A (START / STOP)
*2:
Minute hand
*3:
Chronograph second hand

TECHNICAL GUIDE 8T68A
[ Standard measurement ]
・Press button A to start the
・Press button A again to stop the ・Press button B to reset the
chronograph. chronograph. chronograph.
The chronograph second The chronograph hands stop to
All the chronograph hands
hand will start moving. indicate the elapsed time. will be reset to "0" position.
Note
The chronograph can measure up to 60 minutes.
The chronograph stops after a measurement for 60 minutes.
*Restart in the following procedure.
*During the chronograph operation, button B (reset) can be pushed. There is no problem with the function.
[ Accumulated elapsed time measurement ]
A / A ･･･
B
*Restart and stop of the chronograph can be repeated as many times as necessary by pressing button A
16/19
Press the buttons in the following order :
A
A
START
RESET
( 20 minutes 10 seconds )
RESET
Button B
(RESET)
Button A
(START)
START
STOP (Finish)
( 8 minute 40 seconds )
( 20 minutes 10 seconds )
STOP / RESTART
STOP
HOW TO USE THE CHRONOGRAPH
Press the buttons in the following order :
A
A
B

TECHNICAL GUIDE
8T68A
●Water resistance test
Check the water resistance according to the designated specification of the watch
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 DIVERIS （AIR DIVERIS）150 m 18.75 BAR ＝150(m)times 0.125
SCUBA DIVERIS (AIR DIVERIS)200 m
25 BAR ＝200(m)times 0.125
He-GAS DIVERIS 300 m
37.5 BAR ＝300(m)times 0.125
He-GAS DIVERIS 600 m
75 BAR ＝600(m)times 0.125
He-GAS DIVERIS1000m
125 BAR ＝1000(m)times 0.125
17/19
Condensation test
Condensation test
Water pressure test
Air leak test
Water pressure test
Condensation test

TECHNICAL GUIDE 8T68A
Symptom Possible causes Solutions
Movement The watch stops operating. The battery has been depleted.
Measure the battery voltage.
Replace the battery with a new
one.
The hour wheel and the pinion of Check the relevant parts, and
the minute wheel are not properly replace the damaged parts with
engaged. (Or the teeth of the hour new ones.
wheel and/or minute wheel have
been broken.)
The hooking portions of the Securely attach the hooks of the
circuit block cover are not circuit block cover to the main
properly engaged, resulting in plate.
poor conductivity.
The coil is broken. Measure the coil block resistance.
Replace the coil with a new one.
One or more wheels have been Remove dirt or dust and clean the
contaminated with dirt, dust or contaminated wheels. Be careful
other particles. so as not to damage the teeth of
the plastic parts while cleaning.
An excessive amount of oil in the
movement has caused adhesive
forces among the parts. (wringing)
The current consumption Dirt, dust or foreign particles are Remove dirt, dust or foreign
for the whole movement adhered to the movement. particles and clean the movement.
exceeds the standard The driving pulse is generated in If the current consumption for
value. order to compensate the excessive the circuit block alone is within
load applied to the wheels. (The the standard value range,
oil has deteriorated, leaked or run overhaul and clean the movement
out.) parts, and then make the
measurement again.
The current consumption The light f rom out side the Shut out the light, and make the
for the circuit block alone movement is affecting the measurement again.
exceeds the standard measurement.
value. There is a defect in the IC Replace the circuit block with a
( integrated circuit ) . new one.
18/19
TROUBLESHOOTING

TECHNICAL GUIDE
8T68A
Symptom Possible causes Solutions
STOPWATCH One or more STOPWATCH The relevant coil is broken. Measure the coil block resistance.
hands have stopped moving Replace the coil with a new one if
or show an abnormal move- necessary.
ment. An excessive load is being Clean the relevant parts and
applied to the chronograph lubr icate with an adequate
wheels due to dust or foreign amount of oil.
par ticles adhering to them or
oil starvation.
The step motor shows an There is a crack on the circuit Replace the circuit block with a
abnormal movement. block switch pattern. new one.
The step motor has been deformed. Replace the stator with a new
one.
The buttons do not operate The amount of oil around the Clean the buttons and lubricate
normally. buttons is insufficient. appropriately.
The circuit block pat tern has Adjust the circuit block pattern
been broken or bent. or replace the circuit block with a
new one.
Exterior The crown falls off. The winding stem is not securely Check the main plate, winding
Parts installed. (The setting lever and stem, set ting lever and yoke.
yoke are disengaged.) Replace the defective parts with
new ones.
The current consumption An excessive load is being Adjust or remount the relevant
exceeds the standard value. applied due to friction among hands.
the hour, minute and STOP-
WATCH hands.
Small amount of water/ Water resistance is deteriorated. Investigate the causes to take
blur inside of the glass The watch has been subjected to necessary measures , while
persists. water pressure that exceeds the cleaning inside of the watch.
guaranteed degree.
19/19
TROUBLESHOOTING