Seiko A860A, A861A Parts Catalogue /technical Manual

1

PARTS CATALOGUE / TECHNICAL GUIDE

Cal. A860A
Cal. A861A

[SPECIFICATIONS]

Cal. No.

Item

A860A A861A

(x 1.0)The illustrations refer to Cal. A860A.

Module

Module size Outside diameter ø32.0 mm

31.6 mm between 3 o’clock and 9 o’clock sides

31.7 mm between 6 o’clock and 12 o’clock sides

–Casing diameter

Height 7.1 mm (Including the battery portion)

Display medium Nematic Liquid Crystal, FEM (Field Effect Mode)

Liquid crystal driving system

Multiplex driving system

Display system • Time display

• Stopwatch display (In 1/100 second increments for the first 20 minutes)

• Alarm display

Additional mechanism • Speaking function (Current time, stopwatch measurements, hourly

time signal, alarm time and selected digits to be adjusted)

• Battery life indicator

• Alarm test system

Loss/gain Monthly rate at normal temperature range: less than 20 seconds
Regulation system

Nil

Measuring gate by quartz tester Any gate can be used.
Battery SEIKO CR2025, Maxell CR2025, Sony CR2025, Matsushita CR2025,

Eveready ECR2025
Battery life is approximately 2 years.
Voltage: 3.0 V

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PARTS CATALOGUE

Cal. A860A, A861A

Disassembling procedures Figs. : 1 → 21
Reassembling procedures Figs. : 21 ← 1

Lubricating: Types of oil Oil quantity

Silicone oil 500,000 Normal quantity

➡➡

Please see the remarks on the following pages.

1 Case back screw

2 Case back

3 Case back gasket

4 Module

5 Spacer screw

6 Spacer

7 4580 009

Speaker block

8 Conductive plate for the side button

9 Conductive plate for the front button

Button B

Button A

Button C

Button spring clip

Button D

(Front button)

3

PARTS CATALOGUE

Cal. A860A, A861A

110 151
Installing direction
indication sheet

➡➡

Please see the remarks on the following pages.

(Reversed battery guard)

(Reversed liquid crystal panel frame)

10 4225 435

Battery clamp

11 Battery

(See the front page.)

12 4245 280

Switch spring (A)

13 4408 068

Washer for switch spring (B)

14 4245 270

Switch spring (B)

15 4395 038

Battery guard

16 4270 371

Battery connection (-)

17 4003 190

Circuit block

18 4313 117

Connector

19 4246 087

Speaker lead
terminal

21 4512 033

Liquid crystal
panel frame

20 4510 355

Liquid crystal
panel

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TECHNICAL GUIDE

Cal. A860A, A861A

• The explanation here is only for the particular points of Cal. A860A and A861A.

• For the repairing, checking and measuring procedures, refer to the “TECHNICAL GUIDE, GENERAL

INSTRUCTIONS”.

I. STRUCTURE OF THE CIRCUIT BLOCK

Input terminal (+)

Crystal unit

Input terminal (–)

C-MOS-IC

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 follow either of the two methods below to reset the circuit.

• METHOD 1
To reset the circuit of a module:

Short-circuit the AC terminal of the circuit block and the
battery positive surface with conductive tweezers as
illustrated at right.

* When the circuit is reset , “AM 12:00 oo” is displayed as the seconds start counting immediately.
* After resetting the circuit, set the time. (See “HOW TO USE”.)

AC terminal

Tweezers

Battery (+) side

• METHOD 2
To reset the circuit of a complete watch:

Press and hold buttons “A”, “B”, “C” and “D” at the same
time for 2 to 3 seconds.

* The display will become blank, indicating that the circuit

is reset.

Button CButton B

Button D

Button A