Casio ABX-68B, Repair Manual, Page: 12 / 52

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3. Quality Evaluation and Replacement of Electronic Parts
Tool used
3-1 Capacitors/Chip
Capacitors/chip consist of two extremely thin metal plates
(electrodes), combined as shown in the drawing, sur-
rounded by a ceramic covering. The function of the ca-
pacitor/chip is to store electrical charge. (Fig. 3-1) It has
the characteristic of allowing the flow of alternating cur-
rent but not direct current.
The capacitors/chip may be damaged by an internal short
circuit to crack. (Fig. 3-2)
In quartz watches, capacitors/chip are typically used in
the voltage doubling circuits (VSS1, VSS2, VSS3) that
produce the driving voltage for the LCD display, and in
the pulse generators (VC, VCC/VC1, VC2) for driving the
LSI or in the power supply (VCH) for the LSI block. In
addition, as one method of adjusting the accuracy of the
watch, a capacitor/chip is selected corresponding to the
variation in accuracy of the oscillator/quartz instead of a
capacitor/trimmer. Quality evaluation of capacitors/chip
is performed using a multi-meter according to the follow-
ing procedure.
1) Remove the capacitor/chip to be inspected from the P.C.B.
2) Set the multimeter to the 1 K
Ω
or 10 K
Ω
range.
3) Place the probe of the multimeter against two electrodes of the capacitor/chip to observe the state
of charging and discharging. If the capacitor/chip is acceptable, the multimeter will display a cer-
tain constant resistance value since electricity initially is charged within the capacitor/chip (the
resistance value varies according to the type of capacitor/chip). When charging is completed, the
resistance value reaches infinity, and the needle returns to its original position. (Fig. 3-3) If the
capacitor/chip is defective, the needle will point to 0
Ω
(indicating a short) or remain at
∞
(indicating
an open circuit).
Fig. 3-2
Fig. 3-1
Fig. 3-3
Ceramic
Terminals
for solder
Crack Short circuit
Capacitor/Chip
NO. Code No. Tool name
1 1904 5153 HP-fingerstall (two set)
2 1904 5277 Multimeter
3 1901 9523 Precision tweezers
4-1 1904 1667 Soldering iron (110 V/117 V)
4-2 1904 1668 Soldering iron (220 V)
5 1901 9868 Solder wick
6 1901 9401 Solder
7 Lead wire
8 Alligator clip
9 IC clip