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Seiko 6R20A Technical Manual & Parts Catalogue
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Seiko 6R20A Technical Manual & Parts Catalogue

Seiko 6R20A Technical Manual & Parts Catalogue

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PARTS CATALOGUE / TECHNICAL GUIDE
[SPECIFICATIONS]
Cal. No.
Item
Movement
Movement
Outside diameter
size
Casing diameter
Height
Time indication
Vibration per hour
Basic mechanism
Additional mechanism
Original
Crown
First click
operation
Second click
Loss/gain
Number of Jewels
Cal. 6R20A
l 3 hands (hour, minute and second hands)
l Date/Day indication
l Power reserve indicator
28,800 Hz/hour (8 beats per second)
l Mechanical watch
l 3 hands
l Automatic winding with auxiliary hand winding mechanism
l Date hand, Day hand, and Power reserve indicator
l Date/Day correction function
l Second hand stop mechanism
l Clearance 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 -5 seconds and +25 seconds per day
29 jewels
/24
6R20A
Ø 27.4 mm
Ø 27.0 mm
6.5 mm
(x 1.0)

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Summary of Contents for Seiko 6R20A

  • Page 1 PARTS CATALOGUE / TECHNICAL GUIDE Cal. 6R20A [SPECIFICATIONS] Cal. No. 6R20A Item Movement (x 1.0) Movement Ø 27.4 mm Outside diameter size Ø 27.0 mm Casing diameter 6.5 mm Height l 3 hands (hour, minute and second hands) Time indication...

  • Page 2: Parts Catalogue

    PARTS CATALOGUE Cal. 6R20A Disassembling procedures Figs.: 1 Reassembling procedures Figs.: y h 3 Hour hand 1 Second hand 2 Minute hand 4 Power reserve indicator 5 Date hand 6 Day hand 7 Dial 9 Auxiliary train wheel bridge 026 025 8 Auxiliary train wheel bridge screw (4 pcs.)
  • Page 3 PARTS CATALOGUE Cal. 6R20A qs Barrel arbor pinion 00 267 qd Planetary reduction wheel 026 002 q; Power reserve qf Second sun wheel wheel 009 004 09 002 qg Sun and planet unit qa Intermediate power 00 025 reserve wheel...
  • Page 4 PARTS CATALOGUE Cal. 6R20A e; Oscillating weight 0509 266 Balance bridge (complete set) ea Balance bridge screw 0171 117 0012 420 es Balance staff (balance complete with stud and balance bridge) Balance complete set without stud 0310 048 ed Pallet bridge screw (2pcs.)
  • Page 5 0012 067 Remarks The correct parts for the following are determined based on the design of the cases. Refer to "SEIKO Watch Par ts Catalogue (SEIKO WATCH SERVICE SITE)" to choose corresponding parts. Holding ring for dial Date indicator Winding stem...
  • Page 6 TECHNICAL GUIDE Cal. 6R20A pRepARAtion how to Remove And instAll the bAlAnCe stAff how to remove how to install Initial phase Initial phase Set the balance complete with stud and balance bridge Set a new balance complete with stud to the main plate.

  • Page 7: Technical Guide

    TECHNICAL GUIDE Cal. 6R20A TECHNICAL GUIDE Cal. 6R20A PREPARATION PREPARATION . Lubricate the lower shock absorbing cap jewel, and set it to the lower hole jewel with frame. Type of oil: AO-3 (Moebius A) 2. Set the lower hole jewel with frame (with the cap jewel attached) to the main plate with lower shock absorbing frame.
  • Page 8 TECHNICAL GUIDE Cal. 6R20A TECHNICAL GUIDE PREPARATION . 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.
  • Page 9 TECHNICAL GUIDE TECHNICAL GUIDE Cal. 6R20A PREPARATION . Lubricate at the t wo points in the point of contact between the magic lever and the first reduction wheel and arbor. Type of oil: S-4 . S e t t h e m a g i c l e v e r t o t h e f i r s t reduction wheel and arbor.
  • Page 10 TECHNICAL GUIDE Cal. 6R20A PREPARATION ,2. Lubricate the upper pivot hole jewel for the third wheel and pinion and fifth wheel and pinion. Type of oil: AO-3 (Moebius A) 3. Lubricate the upper hole jewel for the forth wheel and pinion.
  • Page 11 TECHNICAL GUIDE Cal. 6R20A ReAssemble the movement 1. Set the center wheel on the front side. 3. Cannon pinion Turn the main plate upside down. 2. Lubricate the point of contact between the center wheel and the cannon pinion as illustrated.
  • Page 12 TECHNICAL GUIDE Cal. 6R20A ReAssemble the movement 1. Lubricate the winding stem as illustrated. 2. Clutch wheel Type of oil: S-6 2. Winding pinion 2. Day-date corrector setting transmission wheel A 2. Set the winding stem to the main plate.
  • Page 13 TECHNICAL GUIDE Cal. 6R20A ReAssemble the movement 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.
  • Page 14 TECHNICAL GUIDE Cal. 6R20A ReAssemble the movement 1 Barrel & train wheel bridge 1. Set the barrel & train wheel bridge. 2. Tighten the barrel & train wheel bridge screws. (3 pcs.) 1. Slide the pawl lever aside, and then set the ratchet wheel.
  • Page 15 TECHNICAL GUIDE Cal. 6R20A ReAssemble the movement 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.
  • Page 16 TECHNICAL GUIDE Cal. 6R20A ReAssemble the movement 1. Set the balance complete with stud and balance bridge. 2. Make sure the hairspring is properly adjusted. CONCAVE CONVEX STEP SLANT 1. Set the minute wheel & pinion. 2 Hour wheel 2. Lubricate the lateral surface of the hour wheel as illustrated, and then set the hour wheel.
  • Page 17 TECHNICAL GUIDE Cal. 6R20A ReAssemble the movement 1. Set the auxiliary main plate. 2. Tighten the auxiliary main plate screw. 1 Auxiliary main plate 1. Set the day driving wheel. 4 Day jumper 2. Set the day-date corrector setting unit.
  • Page 18 TECHNICAL GUIDE Cal. 6R20A ReAssemble the movement 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.
  • Page 19 TECHNICAL GUIDE Cal. 6R20A ReAssemble the movement 5　Second sun wheel 1. Set the sun wheel. 2. Lubricate the sun wheel as illustrated. (4 points) Type of oil: S-6 3 Sun and planet unit 1　Sun wheel 3. Set the sun and planet unit.
  • Page 20 TECHNICAL GUIDE Cal. 6R20A ReAssemble the movement 1. Lubricate the date jumper as illustrated. Type of oil: AO-3 (Moebius A) 4 Auxiliary train wheel bridge screws (4 pcs) 3 Auxiliary train wheel bridge 2. Lubricate the day jumper as illustrated.
  • Page 21 TECHNICAL GUIDE Cal. 6R20A how to Adjust the hAiRspRing 1. Names of the parts A: Stud B: Regulator pin C: Regulator arm D: Stud support Maximum clearance Minimum clearance 2. Rotate B to fine-tune the position of the outer end of the hairspring...
  • Page 22 TECHNICAL GUIDE Cal. 6R20A ReAssemble the movement 1. Set the oscillating weight and tighten the screw. * Make sure that the oscillating weight is correctly positioned. 22/24...
  • Page 23 TECHNICAL GUIDE Cal. 6R20A MOUNTING OF CASING . Pull out the crown to the second click. Confirming the setting While turning the crown clock wise to turn the hands, look through the circular positions of date wheel holes of auxiliar y train wheel bridge...
  • Page 24 TECHNICAL GUIDE Cal. 6R20A MOUNTING OF CASING . Set the power reserve indicator *Wind the mainspring of the barrel complete fully, and then set the power reserve indicator with pointing its tip to the ”full” position of the power reserve indication on the dial.