Seiko 7K52A Installer manual

1
PARTS CATALOGUE / TECHNICAL GUIDE
Cal. 7K52A
CAUTION
The SEIKO SCUBA Cal. 7K52A is intended for use in diving, an inherently hazardous
form of recreation. Therefore, it is absolutely essential that you strictly observe all
instructions for the repairing and checking of the SEIKO SCUBA watch described in
this guide.
Take the greatest possible care when repairing and checking the depth measurement
function as well as the water resistant quality of this watch, because the depth meas-
urement serves as a guideline when the user is making a dive.
In addition, you must fully understand the following:
• This watch is for use in recreational scuba diving (no-decompression diving), and
is not for decompression diving, saturation diving or diving at altitudes.
• It is for use in water having a temperature range of 0°C to 40°C.
• It can measure the depth of sea water correctly, whose specific gravity is 1.025,
but not that of fresh water.
It is recommended that you explain to users the specifications of the watch, limits of
use and cautions on improper use as required. In doing so, refer to the “CAUTION”
included at the beginning of the instruction booklet of the watch.

Cal. 7K52A
2
[SPECIFICATIONS]
Item
Movement
Indication system
Depth measurement part
Time Alarm part
Hour hand
Minute hand
Small second hand
1/10 m depth hand
Diving time hand
Depth hand (Up to 55m)
Maximum depth hand
(advanced by depth hand)
Alarm hour hand
Alarm minute hand
Driving system Step motor (4 pcs.)
0 °C ~ 40 °C
Influence of temperature change of 20 °C
Within ±1 m
Loss/gain Monthly rate at normal temperature range : less than 15 seconds
Regulation system Nil
Cal. No. 7K52A
Temperature range providing warrantable
accuracy
Within ±(displayed value x 3 % + 0.5 m)
Movement
size
Outside diameter
Casing diameter
Height
ø31.0 mm
ø30.0 mm
5.9 mm
•Electronic circuit reset switch
•Train wheel setting device
•Battery life indicator
•Date calendar
•Instant setting device for date calendar
•Full automatic measurement of div-
ing data
•Recall of log data
•Depth warning function
•Single-time alarm function
Additional functions
Accuracy of the depth
measurement
Battery
Measuring gate by quartz tester
In sea water at a stable temperature
(x 1.0)
Jewels 0 jewel
Use 10-second gate.
Voltage : 3.0 V
Battery life is approximately 2 years.
SEIKO CR2016, Maxell CR2016, Sanyo CR2016, Matsushita CR2016,
Eveready CR2016

Cal. 7K52A
Please see the remarks on the following pages.
Disassembling procedures Figs. : 1 →101
Reassembling procedures Figs. : 101 →1
Lubricating: Types of oil Oil quantity
Moebius A Normal quantity
SEIKO Watch Oil S-6 Extremely small
Silicone oil 500,000 c.s.
5 Movement
PARTS CATALOGUE
Piezoelectric element
3 Case ring
21 Dial
6 Gasket for sensor unit
10 Button at the 8 o’clock side
14 Hour hand
13 Minute hand
12 Diving time hand
16 Depth hand
17 1/10 m depth hand
18 Small second hand
19 Alarm minute hand
20 Alarm hour hand
15 Maximum depth hand
22 0491 623
Dial washer
Cal. 7K52A
11 case
3
7 Button spring clip
9 Button at the 10
o’clock side
8 Button at the 2 o’clock side
23 gasket
4 Crown (with winding stem)
Lubricating of some parts is shown in “III. REMARKS ON DISASSEMBLING AND REASSEMBLING”.
1 Case back
2 Case back gasket
Insulator
0494696
(Revised: 2007/09/13
changed the part name
to Insulator from gasket)

Cal. 7K52A
4
30 1002 619
Maximum depth hand wheel
PARTS CATALOGUE
0012 354
• Circuit block cover A screw (3 pcs.)
• Circuit block cover B screw (1 pc.)
• Date dial guard screw (2 pcs.)
0022 230
• Battery clamp screw (2 pcs.)
• Sensor clamp screw (1 pc.)
• Anti-magnetic shield plate
screw (2 pcs.)
Lubricating of some parts is shown in “III. REMARKS ON DISASSEMBLING AND REASSEMBLING”.
Please see the remarks on the following pages.
31 Date dial
24 0012 354
Date dial guard screw
25 4283 612
Depth hand wheel clamp
28 0808 606
Date dial guard
29 1018 610
Setting lever spring for maximum
depth hand
32 0012 354
Anti-magnetic shield plate screw
34 0810 606
Date jumper
39 0271 614
Hour wheel for alarm
• Spacer for circuit block screw (1 pc.)
27 1017 610
Setting lever for maximum
depth hand
38 0962 580
First intermediate wheel for
calendar correction
26 1002 618
Depth hand wheel
33 4259 691
Anti-magnetic shield plate
40 0271 616
Hour wheel
37 0962 590
Second intermediate wheel for
calendar correction
35 0802 605
Date driving wheel
36 0737 590
Calendar corrector setting wheel

Cal. 7K52A
47 4000 695
Sensor circuit block
Lubricating of some parts is shown in “III. REMARKS ON DISASSEMBLING AND REASSEMBLING”.
Please see the remarks on the following pages.
52 4216 691
Insulator for circuit
block
54 4457 813
Circuit block cover (B)
58 4000 696
Circuit block
PARTS CATALOGUE
43 Battery
44 4531 692
Circuit block guard
45 0022 230
Sensor clamp screw
46 4283 611
Sensor clamp
42 4225 692
Battery clamp
(with AC comment sheet)
41 0022 230
Battery clamp
screw
48 0022 230
Spacer for circuit
block screw
49 0439 612
Spacer for circuit block
50 4246 693
Buzzer lead terminal
51 4000 694
A/D circuit block
53 0012 354
Circuit block cover
(B) screw
55 0012 354
Circuit block cover (A)
screw
59 4270 690
Battery connection (-)
60 4246 691
Switch lead terminal
(A)
56 4457 812
Circuit block cover (A)
57 0396 610
Friction spring for
second counting
5

Cal. 7K52A
6
76 1002 617
1/10 m depth hand wheel
75 0817 617
Intermediate wheel for 1/10 m depth hand
Lubricating of some parts is shown in “III. REMARKS ON DISASSEMBLING AND REASSEMBLING”.
Please see the remarks on the following pages.
61 0027 974
Pin for train wheel bridge
66 1002 620
Diving time wheel
PARTS CATALOGUE
62 0125 610
Train wheel bridge
63 0950 590
Intermediate alarm wheel
64 0270 610
Center wheel for alarm
67 0241 583
Fourth wheel and pinion
68 0240 610
Second wheel
70 0231 580
Third wheel and pinion
71 0261 612
Minute wheel
72 0281 580
Setting wheel
73 0885 590
First intermediate wheel for diving time hand
65 0261 583
Minute wheel for alarm
69 0701 580
Fifth wheel and pinion
74 0885 591
Second intermediate wheel for diving time hand
77 0817 616
Intermediate wheel for depth hand
78 4283 581
Spacer for center wheel and pinion
79 0221 613
Center wheel and pinion
6

Cal. 7K52A
Lubricating of some parts is shown in “III. REMARKS ON DISASSEMBLING AND REASSEMBLING”.
Please see the remarks on the following pages.
80 4146 612
Step rotor
PARTS CATALOGUE
83 4146 612
Step rotor for 1/10 m depth hand
82 4146 612
Step rotor for alarm
81 4146 612
Step rotor for diving time hand
86 4002 693
Coil block for alarm
85 4002 690
Coil block for diving time hand
99 4450 690
Switch lever (A)
98 4450 701
Switch lever (B)
97 4450 702
Switch lever (C)
96 4239 693
Rotor stator for 1/10 m depth hand
95 4239 693
Rotor stator for alarm
94 4239 692
Rotor stator for diving time hand
93 4239 690
Rotor stator
92 0282 580
Clutch wheel
91 Winding stem (with crown)
90 0383 592
Setting lever
89 0391 591
Train wheel setting lever
88 0384 580
Yoke
87 4002 693
Coil block for 1/10 m depth hand
84 4002 690
Coil block
7
100 4242 700
Plus lead terminal
101 0100 612
Main plate

PARTS CATALOGUE
Part No.
0878 910
Position of crown
3 o’clock
Position of date frame Color of figure
White
Color of background
Black
• The explanation here is only for the particular points of Cal. 7K52A.
• For the repairing, checking and measuring procedures, refer to the “TECHNICAL GUIDE , GENERAL IN-
STRUCTIONS”.
The winding stem and crown form an inseparable unit. The winding stem alone, therefore, is unavailable
for supply but supplied as part of the crown. Check the case number and refer to “SEIKO Casing Parts
Catalogue” to choose a corresponding crown.
The type of date dial is determined based on the design of cases. Check the case number and refer to
“SEIKO Casing Parts Catalogue” to choose a corresponding date dial.
Pressure sensor
A/D - IC
Input terminal (+)
Output terminal
Output terminal
Crystal unit
Output terminal
Output terminal
Input terminal (-)
CPU-IC
<Circuit block>
TECHNICAL GUIDE
<Sensor circuit block><A/D circuit block>
Cal. 7K52A
Cal. 7K52A
Between 4 and 5 o'clock
I. STRUCTURE OF THE CIRCUIT BLOCK
31 Date dial
8
␣91 Winding stem (with crown)

Short-circuit.
1) Pull out the crown to the second click.
2) Press the button at the 2 o’clock side to reset the depth and 1/10 m depth hands to the 12 o'clock
position (0m).
3) Press the button at the 10 o’clock side to reset the diving time hand to “0” position.
4) Press the button at the 8 o’clock side to set the alarm hands to the current time.
(Here, also set the hour and minute hands to the current time.)
* The hands advance quickly if the respective buttons are kept pressed for 1 to 2 seconds.
• How to reset the depth, 1/10 m depth and diving time hands to “0” position, and how to set the alarm
hands to the current time
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 short-circuit the AC terminal and the battery connection (+) (circuit block guard) to
reset the circuit as illustrated below.
After resetting the circuit, be sure to reset the depth, 1/10 m depth, maximum depth and diving time
hands to “0” position, and then set the current time.
TECHNICAL GUIDE
9
Cal. 7K52A
• Note on the demonstration function of the hands
Use the demonstration function to check that each hand moves properly.
1) Pull out the crown to the first click.
2) After the depth, maximum depth and diving time hands are all reset to “0” position, press the
button at the 10 o’clock side for more than 2 seconds.
Diving time hand Alarm hour and minute hands 1/10 m depth hand
Crown at the second click

Cal. 7K52A
10
TECHNICAL GUIDE
III. REMARKS ON DISASSEMBLING AND REASSEMBLING
The switch lead terminal is
slipped into the gap under the
auto switch terminal.
<Improper contact>
<Proper contact>
5 Movement
When installing the movement into the case, check that the switch lead terminal (A) securely makes contact
with the auto switch terminal of the case.
Note : Be sure to observe the following to prevent any difference of indication between the depth and
maximum depth hands.
• After pressing the button at the 2 o’clock side in step "4" above, be careful not to give the watch any
vibration or impact until you finish installing the maximum depth hand.
• Push in the hands straight from above, taking care not to turn them.
*After installing the hands, recall the log data to check that :
• there is no difference of indication between the depth and the maximum depth hands.
• when the depth hand returns to indicate the average depth, the maximum depth hand stays where it
was advanced by the depth hand.
Switch lead terminal (A) Auto switch terminal
15 Maximum depth hand
17 1/10 m depth hand
16 Depth hand
10
1/10 m depth hand
Depth hand
Maximum depth
hand
• Remarks on installing
• When installing the hands for diving measurement, check
that they accurately point to the diving measurement
scales on the dial.
• The depth hand moves correspondingly with the 1/10 m
depth hand, and the maximum depth hand is advanced by
the depth hand. To install them, therefore, be sure to
follow the procedure below.
1) Reset the circuit.
2) Pull out the crown to the second click and wait for more
than 40 seconds until all the wheels on the train wheel
bridge stop moving.
3) Reset the 1/10 m depth and depth hands to “0” posi-
tion as shown in the illustration at upper right.
4) After pressing the button at the 2 o’clock side more
than 15 times, put the maximum depth hand exactly
onto the depth hand as shown in the illustration at right.

Cal. 7K52A
2) Hook the setting lever spring for maximum depth
hand to the “C” portion of the setting lever.
In doing so, pull the end portion of the setting lever
spring in the direction of the arrow with tweezers,
taking care not to deform the spring.
Take care not to deform both teeth of the setting
lever for maximum depth hand and of the date
dial guard.
TECHNICAL GUIDE
• How to recall the log data :
Tweezers
“C” portion
Setting lever spring for
maximum depth hand
Setting lever for
maximum depth
hand
Note :
23 Gasket
Push in the gasket until it touches the sensor board as
shown in the illustration at right.
Slit
Note : Take care not to press down the hooked
portion ("A") of the depth hand wheel.
26 Depth hand wheel
• How to install
Set the depth hand wheel so that the post of the set-
ting lever for maximum depth hand is positioned in the
slit of the depth wheel.
“A” portion
Post of the setting
lever for maximum
depth hand
Depth hand wheel
“B” portion
“A” portion
Setting lever for
maximum depth
hand
11
Date dial guard
Maximum depth wheel
• How to install
1) Set the setting lever for maximum depth hand on the
maximum depth hand wheel in such a manner that
its teeth (“A” portion) stay inside the teeth of the date
dial guard (“B” portion), as shown in the illustration
at right.
Notes : • Do not remove the gasket except when it needs
to be replaced with a new one.
• Do not apply silicone oil to the gasket.
Sensor
Gasket
Sensor
board
27 Setting lever for maximum depth hand
28 Date dial guard
Press the button at the 10 o’clock side with the crown at the normal position.
(By pressing the button 3 times, a beep sounds and the display returns to the TIME/CALENDAR.)
Insulator
Insulator
insulator
Insulator

Cal. 7K52A
12
TECHNICAL GUIDE
12
• Check if the end portion of the setting lever spring for maxi-
mum depth hand is positioned on the setting position mark in-
scribed on the maximum depth hand wheel. If not, turn the pin
for setting lever spring with a screwdriver to adjust the setting
position.
38 First intermediate wheel for calendar correction
37 Second intermediate wheel for calendar correction
Pin for setting lever spring
Maximum depth wheel
Setting position mark
29 Setting lever spring for maximum depth hand
• It is not necessary to remove the setting lever spring for maxi-
mum depth hand from the maximum depth hand wheel except
when it needs to be replaced with a new one.
Second intermediate wheel for calendar correction First intermediate wheel for calendar correction
• Lubricating
Refer to the illustrations below.
47 Sensor circuit block
• Do not touch the gel surface of the sensor with tweezers or
fingers.
• If it is soiled, lightly rinse it with fresh water and leave it un-
touched until it is thoroughly dry.
• Take care not to scratch the side surface of the sensor and keep it
clean, as the gasket for sensor is attached around it.
Gel surface
Side surface of the sensor
Buzzer lead terminal
Spacer for circuit block
50 Buzzer lead terminal
First, set the buzzer lead terminal to the spacer for circuit block,
and then, install them to the movement.

Cal. 7K52A
61 Pin for train wheel bridge
• How to remove
Turn the pins 90°counterclockwise with a screwdriver to
loosen them, and pick them up using rodico.
• How to install
Set the pins properly into the groove as shown in the illustra-
tion, and turn them 90°clockwise with a screwdriver to fix
them.
• Lubricating of the upper pivots for wheels and rotors
After installing the train wheel bridge, lubricate the portions
marked with the lubricating marks in the illustraiton at right.
• Never turn the pins more than 90°clockwise or coun-
terclockwise.
• Be sure to use a screwdriver that fits the slot of the pin
head.
• Never apply undue force to the pins in turning them
using a screwdriver.
TECHNICAL GUIDE
Rodico
“A” portion
Circuit block cover (B)
Circuit block cover (A)
56 Circuit block cover (A)
Notes :
13
Friction spring for second counting
54 Circuit block cover (B)
• Pry up the one hooking portion of circuit block cover (B) and the three hooking portions of the circuit
block cover (A) with the tip of a screwdriver to remove them.
• When installing the circuit block covers, check that the hooking portions securely catch the main plate.
57 Friction spring for second counting
Slip the "A" portion of the friction spring for second counting into the gap under the train wheel bridge as
shown in the illusrations below.

Cal. 7K52A
14
69 0701 580
Fifth wheel and pinion
68 0240 610
Second wheel
81 4146 612
Step rotor for diving time
hand
77 0817 616
Intermediate wheel for
depth hand
65 0261 583
Minute wheel for alarm
71 0261 612
Minute wheel
72 0281 580
Setting wheel
66 1002 620
Diving time wheel
73 0885 590
First intermediate wheel
for diving time hand
TECHNICAL GUIDE
82 4146 612
Step rotor for alarm
83 4146 612
Step rotor for 1/10 m
depth hand
64 0270 610
Center wheel for
alarm
Before setting the train wheel bridge, be sure to check that each wheel is set at the right position and the
lower pivot is inserted correctly.
67 0241 583
Forth wheel
and pinion
80 4146 612
Step rotor
70 0231 580
Third wheel and
pinion
63 0950 590
Intermediate
alarm wheel
75 0817 617
Intermediate wheel for
1/10 m depth hand
74 0885 591
Second intermediate
wheel for diving time
hand
Setting position of the spacer for center
wheel pinion
76 1002 617
1/10 m depth hand wheel
14
62 Train wheel bridge

Cal. 7K52A
TECHNICAL GUIDE
91 Winding stem (with crown)
• Remarks on installing
To remove the winding stem (with crown), pull out the crown to the first click, and then, pull out the
setting lever (“A” portion in the illustration below) while pressing it.
99 Switch lever (A)
• Setting position and lubricating
Yoke
Setting lever
Setting lever
Switch lever (A)
15
“A” portion
79 Center wheel and pinion
• Lubricating
Lubricate the center wheel and pinion as shown in the illustraiton
89 Train wheel setting lever
90 Setting lever
88 Yoke

Cal. 7K52A
16
TECHNICAL GUIDE
98 Switch lever (B)
97 Switch lever (C)
Switch lever (C)
Plus lead terminal
Switch lever (B)
16
Contact portion of the axle hole for
second wheel
Pins for switch levers (B)
and (C)
Switch lever (A) pin
Setting wheel guide
• Axle hole for step rotor
• Axle hole for step rotor for div-
ing time hand
• Axle hole for step rotor for alarm
• Ax le hole for step rotor for 1/10 m
depth hand
IV. VALUE CHECKING
• Coil block resistance
Coil block : 2.8 kΩ~ 3.5 kΩ
Coil block for diving time hand : 2.8 kΩ~ 3.5 kΩ
Coil block for alarm: 1.1 kΩ~ 1.7 kΩ
Coil block for 1/10 m depth hand : 1.1 kΩ~ 1.7 kΩ
• Current consumption
For the whole movement : less than 1.6 µA (with voltage supplied from a battery)
For the circuit block alone : less than 1.4 µA (with voltage supplied from a battery)
•
Before measuring the current consumption, be sure to reset the circuit with the tester connected.
To reset the circuit, refer to “II. REMARKS ON INSTALLING THE BATTERY”.
•
When measuring the current consumption, do not touch the water contact sensor with fingers or short-circuit it.
(If the water contact sensor is short-circuited, the diving function may be activated and increase the cur-
rent consumption. As a result, correct measurement cannot be obtained)
• Time accuracy
When measuring the accuracy, pull out the crown to the first click and set the gate of the quartz tester to "10".
101 Main plate
• Lubricating
100 Plus lead terminal
• Setting postion
Set the switch levers (C) and (B) and the plus lead terminal as shown in the illustrations below.

Cal. 7K52A
Free
Button at 10 o’clock side : Recall of log data and cancellation of the
single-time alarm
Button at 8 o’clock side
: Single-time alarm setting
(The single time alarm function cannot be used while log data is re-
called.)
Counterclockwise : Date setting
Clockwise : Free
Button at 10 o’clock side : Demonstration of the hands by pressing for
2 seconds.
Button at 8 o’clock side : Single-time alarm setting
Time hands setting
Button at 2 o’clock side : Resetting the 1/10 m depth and depth hands
to "0" position.(The depth hand moves correspondingly with the 1/10
m depth hand)
Button at 10 o’clock side : Resetting the diving time hand to "0" positon.
Button at 8 ‘oclock side : Setting the alarm hour and minute hands to the
current time. (The alarm hour hand moves correspondingly with the alarm
minute hand.)
Simultaneous press of buttons at 2 ‘oclock and 10 ‘oclock sides : Resetting
the circuit.
Crown operation
Button operation
Normal position
(Time/calendar display)
Depth hand
Diving time hand
Button at the 10 o’clock side
Extra measurement range warning mark
Button at the 8 o’clock side
Measurement halt warning mark
Maximum depth hand
Alarm hour hand
1/10 m depth hand
Hour hand
Small second hand
Button at the 2 o’clock side
Crown
Date
Alarm minute hand
Minute hand
First click
(Date setting function)
Crown operation
Button operation
Second click
(Time setting function)
TECHNICAL GUIDE
• Function checking
When checking the functions, operate the crown and buttons as follows.
Crown positon
Water contact sensor
Crown operation
Button operation
17

Cal. 7K52A
18
1) While pressing the crown, turn it clockwise to screw it in.
2) Press the button at the 10 o’clock side repeatedly to reset the 1/10 m depth, depth and maximum
depth hands to “0” position.
(If they are at “0” position, it is not necessary to follow this step.)
3) Put the watch into the water tank of Water Resistance Tester S-470, and apply 1.00 kg/cm of pres-
sure.
4) Make a note of the depth displayed by the watch.
5) Apply pressure gradually, and make a note of the depth displayed by the watch when 3.00 kg/cm of
pressure is applied.
6) If the obtained depths fall within the range shown in the table below, the pressure sensor is normal
and accurately measures the depth.
Decreasing the pressure
(More than 15 minutes)
• Remarks on the water resistance test
Increasing the pressure
(More than 15 minutes)
Pressure value
1.00 kg/cm2
3.00 kg/cm2
Depth display of Cal. 7K52A
8.5 ~ 10.5 m
27.5 ~ 30.5 m
TECHNICAL GUIDE
2
2
18
Pressure
Elapsed time
Keeping the pressure constant
97-7 Printed in Japan
• Accuracy of the pressure sensor
To precisely measure the accuracy of the pressure sensor, use Water Resistance Tester S-470, which is equipped
with a transparent water tank and a digital water pressure gauge, or Water Resistance Tester S-461.
Procedure for measuring the accuracy of the pressure sensor (when using Water Resistance Tester S-470.)
1) Use a water pressure type water resistance tester such as S-470 and S-461. Never use an air
pressure type tester as it may cause damage to the pressure sensor.
2) In checking the water resistant quality of the watch using the water resistance tester, increase and
decrease pressure gradually taking more than 15 minutes in each process.
Revision: 2007/09/13