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Troubleshooting - Casio JD-4000BK Service Manual

Dec. 1994

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10. TROUBLESHOOTING

1. Intermittent display
START
Is the Heat seal defective ?
Is the battery contact weak ?
Are there short circuit around the pins
of the LSI (HC3009-01-F1) ?
Is the soldering weak ?
Replace the PCB ass'y
2. Erratic display
START
Is the Heat seal defective ?
Is the LCD defective ?
Are the voltage V0 ~ V4 OK ?
Are there short circuit around the pins of the
LSI (HC3009-01-F1) or between the 2 pins of
the crystal oscillator (·1) ?
Are there short circuit around
the pins of the RAM and ROM ?
Replace the PCB ass'y
Y
N
Y
N
N
Y
N
Y
N
Y
N
N
Y
N
N
— 20 —
Replace
Clean and adjust pressure of contact
Y
Resolder
Resolder
Replace
Replace
Check or replace the chip
capacitors C4 ~ C8
Y
Resolder
Y
Resolder

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