Seiko 6R20A Installer manual

PARTS CATALOGUE/TECHNICALGUIDE
Cal. 6R20A
[SPECIFICATIONS]
Cal. No.
Item
Movement
Movement
size
Time indication
Outside diameter
Casing diameter
Height
Additional mechanism
Loss/gain
Number of Jewels
Basic mechanism
Crown
operation
Original
First click
Second click
Vibration per hour
1/24
28,800 Hz/hour (8 beats per second)
6.15 mm
lMechanical watch
l3 hands
lAutomatic winding with auxiliary hand winding mechanism
(x 1.0)
Ø 27.4 mm
Ø 27.0 mm
lDate hand, Day hand, and Power reserve indicator
lDate/Day correction function
lSecond hand stop mechanism
lClearance adjustment
Manual winding (turn clockwise)
Date correction (turn counterclockwise)/Day correction (turn clockwise)
Time setting (turn clockwise to move forward and counterclockwise to
move back)
Second hand stops on the spot
Between -15 seconds and +25 seconds per day
29 jewels
6R20A
l
3 hands (hour, minute and second hands)
l
Date/Day indication
l
Power reserve indicator

Cal. 6R20A
PARTS CATALOGUE
3 Hour hand
4
Power reserve indicator
5
Date hand
1
Second hand
2
Minute hand
6
Day hand
9Auxiliary train wheel
bridge
0126 025
8Auxiliary train wheel
bridge screw (4 pcs.)
0012 201
7
Dial
Disassembling procedures Figs.: 1y h
Reassembling procedures Figs.: yh
1
2/24

PARTS CATALOGUE Cal. 6R20A
qf
Second sun wheel
1009 004
ql
Date indicator
driving wheel
0802 036
ws Day-date corrector
setting unit
1001 029
qa
Intermediate power
reserve wheel
0817 047
q; Power reserve
wheel
1019 002
qg
Sun and planet unit
1001 025
qh
Sun wheel
1009 003
qd Planetary reduction
wheel
1026 002
qs
Barrel arbor pinion
1010 267
wj
Minute wheel and
pinion
0261 006
wl
Cannon pinion
wf
Day star
0970 003
wd
Day driving wheel
0898 001
wa Date jumper
0810 017
wh
Auxiliary main plate
0102 023
w k
Hour wheel
qj
Day jumper
0810 017
q k
Date star
0970 002
wg
Auxiliary main plate
screw
0012 201
w ;
Date corrector
setting wheel
0737 002
3/24

eaBalance bridge screw
0012 420
e;Oscillating weight
0509 266
esBalance staff (balance complete
with stud and balance bridge)
edPallet bridge screw (2pcs.)
0012 354
efPallet bridge
0161 310
egPallet fork
0301 310
ehAutomatic train wheel screw
(2pcs.) 0012 354
ej Automatic train bridge
0191 025
elRatchet wheel screw
0012 919
r;Ratchet wheel
0285 051
raBarrel & train wheel bridge screw
(3 pcs.) 0012 420
rsRatchet sliding wheel spring
0363 156
rdBarrel & train wheel bridge with
upper hole jewel with frame
0112 365
rkLower plate for barrel & train
wheel bridge
0436 001
rjLower plate for barrel & train
wheel bridge screw
0012 354
rlFourth wheel & pinion
0241 216
taClick
0381 004
tsEscape wheel & pinion
0251 310
tdBarrel complete
0201 074
tjYoke spring screw (2pcs.)
0012 168
tkYoke spring
0388 071
tlYoke
0384 061
y;Setting lever
0383 060
yaBalance stop lever
0601 010
yhMain plate
ekSecond reduction wheel & pinion
0514 010
th  Center wheel & pinion
0221 085 (Standard type)
* Remove the cannon pinion
on the back side of the
main plate before removing
the center wheel.
tgCenter wheel bridge
0122 302
tf  Center wheel bridge screw
0012 354
t;  Third wheel & pinion
0231 070
rfReduction wheel holder
0836 002
rh Pawl lever
0831 010
rgFirst reduction wheel & arbor
0511 010
 Balance complete set without stud
0310 048
Balance bridge
(complete set)
0171 117
ysClutch wheel
0282 040
ydWinding pinion
0283 020
yfIntermediate wheel for calendar
correction A
0962 021
ygWinding stem
Cal. 6R20A
PARTS CATALOGUE
4/24

0012 919
0012 354
Ratchet wheel screw
Lower plate barrel & train wheel bridge screw
Center wheel bridge screw
Pallet bridge screw (2pcs.)
Automatic train wheel screw (2pcs.)
Date indicator maintaining plate screw A (3 pcs.)
Parts code Parts name
Yoke spring screw (2pcs.)
Barrel & train wheel bridge screw (3 pcs.)
Balance bridge screw
Casing clamp screw (2 pcs.)
0012 168
0012 420
0012 067
CROSS-SECTION VIEW OF THE SCREW PARTS
0012 201
Auxiliary main plate screw
Auxiliary train wheel bridge screw (4 pcs)
The correct parts for the following are determined based on the design of the cases.
Refer to "SEIKO Watch Parts Catalogue (SEIKO WATCH SERVICE SITE)" to choose
corresponding parts.
 l Holding ring for dial
lDate indicator
lWinding stem
Remarks
PARTS CATALOGUE Cal. 6R20A
5/24

How to remove How to install
1. Initial phase
Set the balance complete with stud and balance bridge
to the main plate.
PREPARATION
HOW TO REMOVE AND INSTALL THE BALANCE STAFF
2. Move the stud support toward the balance bridge until it
is attached to the balance bridge.
* When doing so, make sure that the outer end of the
hairspring is not removed from the regulator arm.
4. Remove the balance bridge and replace the balance
complete with stud with a new one.
3. Temporarily set the stud to the stud support.
Make sure that the hairspring passes outside the pin of
the regulator arm.
* Be careful not to damage the hairspring.
1. Initial phase
Set a new balance complete with stud to the main plate.
2. Set the balance bridge and tighten the balance bridge
screw.
4. Using sturdy tweezers, set the stud to the stud support
and press it down.
Make sure that the outer end of the hairspring passes
through the regulator slot of the regulator arm.
* Be careful not to damage the hairspring.
3. Using sturdy tweezers, push the stud outward from the
direction of the arrow shown in the illustration until it is
removed from the stud support.
TECHNICAL GUIDE Cal. 6R20A
6/24

PREPARATION
PREPARATION
1. Lubricate the lower shock absorbing cap
jewel, and set it to the lower hole jewel
with frame.
2. Set the lower hole jewel with frame (with
the cap jewel attached) to the main plate
with lower shock absorbing frame.
3. Set the shock absorbing spring.
Lubricate at the three points on the rear
of the main plate as illustrated.
1. Lower hole jewel for the minute wheel
pin
2. Lower hole jewel for the sun wheel
3. Lower hole jewel for the planetary
reduction wheel
Type of oil: S-6
Lubricate at the six points on the surface
of the main plate as illustrated.
1. Lower hole jewel for the barrel
complete
2. Lower hole jewel for the pallet fork.
3. Lower hole jewel for the escape wheel
and pinion
4. Lower hole jewel for the first
reduction wheel
5. Lower hole jewel for the third wheel
and pinion
6. Setting lever pin and sliding face of
setting lever
3 1
Type of oil: S-6
Type of oil: S-6
Type of oil: S-6
Type of oil: AO-3 (Moebius A)
Type of oil: AO-3 (Moebius A)
Type of oil: AO-3 (Moebius A)
1
Type of oil: S-6
Type of oil: S-6
Type of oil: S-6
TECHNICAL GUIDE Cal. 6R20A
1
2
3
TECHNICAL GUIDE Cal. 6R20A
2
7/24
2
3
4
5
6

PREPARATION
4
5
6
1. Set the rachet sliding wheel spring.
1. Lubricate the lower hole jewel for the
second reduction wheel and pinion.
Type of oil: S-6
2. Lubricate at the two points in the rachet
sliding wheel.
1
2
Type of oil: S-6
TECHNICAL GUIDE Cal. 6R20A
TECHNICAL GUIDE
1. Lubricate the upper hole jewel for the
third wheel bridge and set the upper hole
jewel with frame. Then, set the upper
shock absorbing spring for the third
wheel bridge.
Type of oil: AO-3 (Moebius A)
2. Lubricate the upper hole jewel for the
escape wheel and pinion and set the
upper hole jewel frame with frame. Then,
set the upper shock absorbing spring for
the escape wheel and pinion.
Type of oil: AO-3 (Moebius A)
8/24

PREPARATION
10
TECHNICAL GUIDE Cal. 6R20A
1. Lubricate at the t wo points in the
point of contact between the magic
lever and the first reduction wheel and
arbor.
1. Lubricate at the arbor of the first
reduction wheel and arbor.
7
8
9
TECHNICAL GUIDE
1. Set the first reduction wheel and arbor
(with the magic lever attached) to the
barrel and train wheel bridge.
2. Set the first reduction wheel and arbor
lever.
Type of oil: S-4
1. S e t th e ma g i c le v e r to t h e f ir s t
reduction wheel and arbor.
9/24
Type of oil: S-4

PREPARATION
1
TECHNICAL GUIDE Cal. 6R20A
1,2. Lubricate the upper pivot hole jewel
for the third wheel and pinion and
fifth wheel and pinion.
11
12
13
3. Lubricate the upper hole jewel for the
forth wheel and pinion.
1. Lubricate at the four points in the
crown wheel.
1. Set the lower plate for barrel and train
wheel bridge.
2. Screw the lower plate for barrel and
train wheel bridge.
2
3
10/24
Type of oil: AO-3 (Moebius A)
Type of oil: AO-3 (Moebius A)
Type of oil: S-6

1. Set the center wheel on the front side.
Turn the main plate upside down.
2. Lubricate the point of contact between
the center wheel and the cannon pinion
as illustrated.
3. Set the cannon pinion to the center
wheel.
3. Cannon pinion
1. Turn the main plate upside down.
2. Lubricate the center wheel & pinion as
illustrated.
2
Type of oil: S-6
Type of oil: S-6
3. Set the escape wheel & pinion.
4. Set the barrel complete.
5. Set the click.
1. Set the center wheel bridge.
2. Tighten the center wheel bridge screws.
(2 pcs.)
3. After tightening the center wheel bridge
screws, make sure that there is adequate
clearance for the center wheel.
5 Click
3 Escape wheel &
pinion
4 Barrel complete
REASSEMBLE THE MOVEMENT
1
2
3
TECHNICAL GUIDE Cal. 6R20A
11/24

1. Lubricate the winding stem as illustrated.
2. Clutch wheel
2. Winding pinion
2. Day-date corrector setting
transmission wheel A
Type of oil: S-6
2. Set the winding stem to the main plate.
While doing so, slide the clutch wheel,
winding pinion and day-date corrector
setting transmission wheel A on the
shaft of the winding stem in the correct
order shown in the illustration.
1. Lubricate the contact points between
the upper and lower tubes of the setting
lever and yoke, and then set the setting
lever.
1 Setting lever
2 Balance stop lever
3 Yoke
2. Set the balance stop lever.
3. Set the yoke.
* Make sure that the yoke is correctly engaged
with the setting lever as shown in the
illustration.
Type of oil: S-6
Type of oil: S-6
4. Lubricate the tail portion of the yoke.
REASSEMBLE THE MOVEMENT
4
5
TECHNICAL GUIDE Cal. 6R20A
12/24

1. Set the yoke spring.
2. Tighten the yoke spring screws. (2 pcs.)
3. Securely engage the yoke over the pin of
the setting lever.
1 Yoke spring
4. Try pulling out the winding stem to check
that it can be done smoothly.
1. Set the third wheel & pinion.
2. Lubricate the convex part of the fourth
wheel & pinion as illustrated, and then set
it.
2 Fourth wheel & pinion.
1 Third wheel & pinion.
Type of oil: AO-3 (Moebius A)
7
REASSEMBLE THE MOVEMENT
6
TECHNICAL GUIDE Cal. 6R20A
13/24

Ratchet wheel setting position
Pawl lever position
1. Set the barrel & train wheel bridge.
2. Tighten the barrel & train wheel bridge
screws. (3 pcs.)
1 Barrel & train wheel bridge
1. Slide the pawl lever aside, and then set
the ratchet wheel.
Notes
1 Ratchet wheel
2. Tighten the ratchet wheel screw.
* Do not tighten the ratchet wheel screw too
much.
3. Try turning the crown clockwise a little at
its original position in order to check that
the wheels turn smoothly.
Align the ratchet wheel with the
chamfered surface of the barrel
complete shown in the illustration.
8
REASSEMBLE THE MOVEMENT
9
TECHNICAL GUIDE Cal. 6R20A
14/24

1. Set the pallet fork.
2. Set the pallet bridge.
3. Make sure that the pallet fork works
smoothly.
2 Pallet bridge
1 Pallet fork
4. Lubricate the arms of the pallet fork as
illustrated.
5. Lubricate the upper hole jewel for the
pallet fork as illustrated.
1. Lubricate the teeth surface of the second
reduction wheel as illustrated.
3 Automatic train bridge
1 Second reduction
wheel & pinion
Type of oil: S-6
2. Lubricate the upper pivot of the second
reduction wheel as illustrated.
Type of oil: S-6
3. Set the automatic train bridge.
4. Tighten the automatic train bridge screws.
(2 pcs.)
Type of oil: AO-3 (Moebius A)
Type of oil: AO-3 (Moebius A)
10
11
REASSEMBLE THE MOVEMENT
TECHNICAL GUIDE Cal. 6R20A
15/24

CONVEX
CONCAVE
STEP SLANT
1. Set the balance complete with stud and
balance bridge.
2. Make sure the hairspring is properly
adjusted.
1. Set the minute wheel & pinion.
2. Lubricate the lateral surface of the hour
wheel as illustrated, and then set the hour
wheel.
2 Hour wheel
1 Minute wheel & pinion
Type of oil: S-6
3. Lubricate the clutch wheel as illustrated.
Type of oil: S-6
12
13
REASSEMBLE THE MOVEMENT
TECHNICAL GUIDE Cal. 6R20A
16/24

1 Auxiliary main plate
1. Set the auxiliary main plate.
2. Tighten the auxiliary main plate screw.
1. Set the day driving wheel.
2. Set the day-date corrector setting unit.
3. Set the day star.
* Make sure that the day driving wheel and day
star are correctly engaged as shown in the
illustration.
Day driving wheel
Day star
Day jumper
4. Set the day jumper.
* Make sure that the day jumper and the day
star are correctly engaged as shown in the
illustration.
Day star
1 Day driving wheel
2 Day-date corrector
setting unit
3 Day star
4 Day jumper
REASSEMBLE THE MOVEMENT
14
15
Align the tip of gear
teeth of the day star with
the notch on the day
driving wheel to ensure
proper orientation.
TECHNICAL GUIDE Cal. 6R20A
17/24

5. Lubricate the shaft of the date star as
illustrated.
Type of oil: S-6
1. Set the date indicator driving wheel.
2. Set the date corrector setting wheel.
3. Set the date star.
* Make sure that the date indicator driving wheel
and date star are correctly engaged as shown in
the illustration.
Date indicator driving wheel
2 Date corrector setting wheel
Date star
Date jumper
4. Set the date jumper.
* Make sure that the date jumper and date star are
correctly engaged as shown in the illustration.
Date star
5. Lubricate the shaft of the date star as
illustrated.
Type of oil: S-6
4 Date jumper
3 Date star
1 Date indicator driving wheel
REASSEMBLE THE MOVEMENT
16
Align the tip of gear
teeth of the date star
with the notch on the
date indicator driving
wheel to ensure proper
orientation.
TECHNICAL GUIDE Cal. 6R20A
18/24

1. Set the sun wheel.
2. Lubricate the sun wheel as illustrated. (4
points)
1 Sun wheel
5 Second sun wheel
3 Sun and planet unit Type of oil: S-6
3. Set the sun and planet unit.
4. Lubricate the sun and planet unit as
illustrated.
Type of oil: AO-3 (Moebius A)
5. Set the second sun wheel.
1. Set and lubricate the planetary reduction
wheel as illustrated.
1 Planetary reduction
wheel
2 Barrel arbor pinion
4 Intermediate power reserve wheel
5 Power reserve wheel
Type of oil: S-6
2. Set the barrel arbor pinion.
3. Lubricate the pinion of the barrel arbor
pinion.
Type of oil: S-6
REASSEMBLE THE MOVEMENT
17
18
Type of oil: S-6
4. Set the intermediate power reserve wheel.
5. Set the power reserve wheel.
6. Lubricate the shaft of the power reserve
wheel as illustrated.
TECHNICAL GUIDE Cal. 6R20A
19/24

1. Lubricate the date jumper as illustrated.
3 Auxiliary train wheel bridge
4 Auxiliary train wheel bridge screws (4 pcs)
Type of oil: AO-3 (Moebius A)
2. Lubricate the day jumper as illustrated.
Type of oil: AO-3 (Moebius A)
3. Set the auxiliary train wheel bridge.
4. Tighten the auxiliary train wheel bridges
screws. (4 pcs)
REASSEMBLE THE MOVEMENT
19
TECHNICAL GUIDE Cal. 6R20A
20/24