Casio JD-4000BK Service Manual page 22

3. No display
START
Is the battery contact weak?
N
Is the battery switch contact weak?
N
Is the AC key contact weak?
N
Are there short circuit around
the pins of the LSI?
N
Is the voltage VCC 3[V] ?
Y
Does the ceramic oscillator oscillate ?
Y
Are the voltage V0 ~ V4 OK ?
N
Are the voltage VD1 ~ VD4 OK ?
Y
Are the voltage VT1 ~ VT4 OK ?
Y
Are the voltage VREG 2 and
VREG 4 OK ?
Y
Is the voltage VREG 3 OK ?
Y
Is the voltage SW OK ?
Y
Replace the PCB ass'y
Y
Clean and adjust pressure of contact
Y
Clean and adjust pressure of contact
Y
Clean or replace the rubber key
Y
Resolder
Check or replace the electrolytic
N
capacitor C1
N
Are the chip capacitors C22, C23 defective ?
Replace the ceramic oscillator
Y
Is the heat seal defective ?
N
Is the LCD defective ?
N
N
Check or replace the chip
capacitor C11, C12
N
Check or replace the chip
capacitor C13, C14
N
Check or replace the chip
capacitor C9 or C16
N
Check or replace the chip
capacitor C18 or C25
N
Check or replace the chip
capacitor C10
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Y
N
Y
Replace
Y
Replace
Replace