Casio ABX-68B, Repair Manual, Page: 50 / 52

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15-4-4 Confirmation
When all parts have been assembled, install the battery and with the crown pulled out, set temporarily
the hand/second and push in the crown to see if the watch runs.
If the hand/second moves normally, remove the hand/second and install the wheel/hour, washer, dial
and hands (hour, minute and second) to the movement.
If the hand/second does not move normally, repeat the disassembly and reassembly procedures.
(Refer to Hand Attachment and Removal in WATCH BASIC REPAIR MANUAL (RANKS C AND D).)
In the case of a waterproof watch, always make sure to perform the waterproof inspection after
repair is completed.
16. Clock Repair (Heat Seal Replacement)
In some digital clocks, the LCD and P.C.B. ass’y are joined with a heat seal. (Fig. 16-1)
Thus, thermal compression bonding of the heat seal must be performed when replacing the LCD,
replacing the P.C.B. ass’y or the display is defective due to a cracked heat seal.
Furthermore, since thermal compression bonding cannot be repeated on a seal once it has cracked, a
new heat seal must be always be used.
Tool used
1) Peel off the old heat seal from the LCD and P.C.B. ass’y.
2) Carefully wipe the bonding surfaces of the LCD and P.C.B. ass’y with a solvent such as acetone
(also referred to as dimethylketone/CH3- CO-CH3) to completely remove all paste of the old heat
seal.
Although isopropyl alcohol ((CH3)2CHO) or other solvents may also be used to wipe the bonding
surfaces, since they do not effectively remove the paste, acetone yields the best results.
Dampen a cloth with acetone and wipe off any paste remaining on the terminal surfaces by wiping
in the perpendicular direction (in the direction of the wiring leading from the components).
3) Attach the heat seal to the LCD by thermal compression bonding.
(This work is generally performed easier by joining the heat seal to the LCD first.)
There are two ways of performing thermal compression bonding: a method that uses a soldering
iron and silicon rubber, and a method that uses a soldering iron and heat seal chips.
Use a soldering iron of at least 60 W when using with silicon rubber, and at least 30 W when using
with heat seal chips.
4) Put one side of the heat seal on the terminal of the LCD.
Be sure the black carbon lines of the heat seal and terminals of the LCD are overlapped exactly.
LCD
Heat seal
P.C.B. ass’y
Fig. 16-1
NO. Code No. Tool name
1 Aceton
2-1 1901 9525 Soldering iron UNI MAX (220 V)
2-2 1901 9532 Soldering iron UNI MAX (117 V)
2-3 1901 9526 Soldering iron UNI MAX (240 V)
3 1901 9516 Heat seal tip (J34674-1)
4 1901 9515 Tip B (J34622-2)
5 5041 2091 Screw (3mm X 5)
6 5021 1134 Screw (1.7mm X 7) X 2pcs.
7 1901 9514 LCD fixing plate
8 6311 9609 Nut (A41984-1) X 2pcs.