Seiko 4205B, 4206B, 4207B, 4208B, 4225A Technical Manual

1

PARTS CATALOGUE / TECHNICAL GUIDE

Cal. 4205B / 4206B / 4207B

4208B / 4225A / 4227A

Movement

Time indication

Outside diameter ø17.5 mm

Casing diameterMovement size ø17.2 mm

Height

5.6 mm

Three hands (Hour, minute and second hands)

Vibrations per hour 21,600 (6 beats per second)

Additional
mechanism

Automatic winding

Jewels 17 jewels

21 jewels

The illustrations refer to Cal. 4206B (x 2.0)

4227A4207B4205B

Cal. No.

Item

[SPECIFICATIONS]

Date calendar
Day and date calendar
Instant calendar (date)

setting device
Instant calendar (day

and date) setting device

4206B

4225A

4208B

ø23.8 mm

ø23.4 mm

5.6 mm

Auxiliary hand winding
mechanism

17 jewels 21 jewels 21 jewels 21 jewels

2

PARTS CATALOGUE

30 0310 421

Balance complete
with stud

28 0012 123

Stud screw

29 0171 426

Balance cock

27 0012 484

Balance cock screw

Diashock

26 0505 421

Transmission wheel
and pinion

25 0831 421

Pawl lever with jewel

23 0012 485

Framework for automatic
device screw

Disassembling procedures Figs. : 1 ~ 61

Reassembling procedures Figs. : 61 ~ 1

Lubricating: Type of oil Oil quantity

Moebius A or AO-32 Liberal quantity

SEIKO Watch Oil S-4 Normal quantity

SEIKO Watch Oil S-6 Extremely small

20 Cannon pinion

19 0802 422

Date driving wheel

18 0817 421

Intermediate date driving
wheel and pinion

17 0261 422

Minute wheel

16 Hour wheel

15 0972 423

Day-date corrector finger

14 0810 420

Date jumper

13 0811 420

Date jumper spring

12 Date dial

11 0808 423

Date dial guard

10 0873 422

Day jumper

9 0012 485

Date dial guard screw

8 0012 797

Day jumper screw

7 0556 422

Date finger

6 0012 485

Date driving wheel
screw

5 Day star with dial disk

3 Holding ring for dial

2 Dial

1 Hour, minute and

second hands

21 0012 488

Oscillating weight
without pinion screw

Cal. 4205B, 4206B, 4207B, 4208B, 4225A, 4227A

4 0963 420

Snap for day star with
dial disk

22 0500 424

Oscillating weight

24 0193 420

Framework for automatic
device with ball bearing

Ex.: Cal. 4206B

33 0301 422

Jewelled pallet fork
and staff

32 0161 420

Pallet cock

31 0012 485

Pallet cock screw

Please see the remarks on the following pages.

➡➡

3

PARTS CATALOGUE

61 Main plate

0100 421 (4205B/4206B)
0100 423 (4207B/4208B)
0100 430 (4225A/4227A)

Diashock

60 Winding stem

59 0283 421

Winding pinion

58 0282 422

Clutch wheel

57 0390 420

Setting lever axle

56 0383 420

Setting lever

55 0384 420

Yoke

54 0388 421

Setting lever
spring

53 0012 484

Setting lever
spring screw

Dial leg pin

51 0251 421

Escape wheel and
pinion

50 0121 420

Center wheel bridge

0540 421
Dial leg holder

49 0012 485

Center wheel
bridge screw

48 0105 420

Lower plate for
balance cock

47 0542 421

Locking seat for idle
wheel

45 0363 420

Sliding crown
wheel spring

46 0237 421

Intermediate
ratchet wheel

44 0012 484

Screw for locking
seat for idle wheel

43 0241 421

Fourth wheel and
pinion

41 Second wheel

pinion

42 0231 421

Third wheel and
pinion

40 0201 420

Complete barrel
with mainspring

39 0285 420

Ratchet wheel

38 0381 420

Click

37 0112 430 (Cal. 4205B, 4206B)

0112 432 (Cal. 4207B, 4208B, 4225A, 4227A)
Barrel and train wheel bridge

36 0396 420

Friction spring for second
wheel pinion

34 0012 485

Barrel and train wheel bridge
screw (B)

35 0012 484

Barrel and train wheel bridge
screw (A)

52 Center wheel with

cannon pinion

➡➡

Please see the remarks on the following pages.

Cal. 4205B, 4206B, 4207B, 4208B, 4225A, 4227A