Seiko 6R20A Installer manual

PARTS CATALOGUE/TECHNICALGUIDE

Cal. 6R20A

[SPECIFICATIONS]

Cal. No.

Item

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

3 hands (hour, minute and second hands)

Date/Day indication

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

2/24

PARTS CATALOGUE Cal. 6R20A

Second sun wheel

1009 004

Date indicator

driving wheel

0802 036

ws Day-date corrector

setting unit

1001 029

Intermediate power

reserve wheel

0817 047

q; Power reserve

wheel

1019 002

Sun and planet unit

1001 025

Sun wheel

1009 003

qd Planetary reduction

wheel

1026 002

Barrel arbor pinion

1010 267

Minute wheel and

pinion

0261 006

Cannon pinion

Day star

0970 003

Day driving wheel

0898 001

wa Date jumper

0810 017

Auxiliary main plate

0102 023

Hour wheel

Day jumper

0810 017

Date star

0970 002

Auxiliary main plate

screw

0012 201

;

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



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



Center wheel bridge screw

0012 354



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

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

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: AO-3 (Moebius A)

Type of oil: S-6

TECHNICAL GUIDE Cal. 6R20A

7/24

PREPARATION

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.

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

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.

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

TECHNICAL GUIDE Cal. 6R20A

1,2. Lubricate the upper pivot hole jewel

for the third wheel and pinion and

ﬁfth wheel and pinion.

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.

10/24

Type of oil: AO-3 (Moebius A)

Type of oil: S-6

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