Table of fault symptoms and countermeasures (for repair)
** The following fault symptoms assume that a product which operated perfectly at the time of shipping has become defective.
Symptom Individual symptom Possible causes Defect location, countermeasures
1 The power cannot be switched on at all. Blown fuse Replace the fuse on the POWER circuit board.
None of the power supplies is put out. IC1150 and D1140 on the POWER circuit board and
their surroundings
+1.8 V is not put out. IC20 and D2 on the MAIN circuit board and their
surroundings
Check that +1.8 V is applied to C13 on the MAIN circuit
board.
The +3.3 V power supply is not put out. IC1410 and L1271 on the POWER circuit board and
their surroundings
POWER circuit board fuse protector FP1400
The +5 V power supply is not put out. IC1302 and D1261 on the POWER circuit board and
their surroundings
Check that +5 V is applied to C15 on the MAIN circuit
board.
The +7 V power supply is not put out. POWER circuit board D1261
Check that +7 V is applied to C19 on the MAIN circuit
board.
The +15 V power supply is not put out. IC1201 on the POWER circuit board and its
surroundings
Power circuit board resistor R1211
The +20 V power supply is not put out. D1271 on the POWER circuit board and its
surroundings
The -15 V power supply is not put out. D1403 on the POWER circuit board and its
surroundings
Microcomputer-related defect IC2, IC14, and IC34 on the MAIN circuit board and their
surroundings
Defective connection between MAIN-JACK
circuit board and POWER-JACK circuit board
Confirmation of the connection cable
Pay attention to the orientation.
Defective oscillation circuit X1, X3, X5 on the MAIN circuit board and their
surroundings
Confirm that X1 oscillates at 8 MHz and X3 and X5 at
27 MHz.
Defective reset circuit IC6 and IC11 on the MAIN circuit board and their
surroundings
Output of +5 V for the output of IC6 on the MAIN circuit
board and output of +3.3 V for the output of IC11
Memory-related defects IC23, IC24, IC25, IC36, and IC38 on the MAIN circuit
board
2 Display-related Nothing is displayed on the LCD. Defective connection between MAIN and LCD
relay circuit board
Connection confirmation, connecting cable replacement
Defective connection between relay circuit
board and LCD
Connection confirmation, FFC cable replacement
Defective LCD control circuit IC1, IC9, and IC13 on the MAIN circuit board and their
surroundings
Defective contrast -15 V power supply IC12, Q7, and Q8 on the MAIN circuit board and their
surroundings
Confirm that approximately -10 V to -13 V is put out to
C6 on the MAIN circuit board.
Defective LCD unit Re
lacement of the LCD unit
Defective microcom
uter on the scratch side IC14 on the MAIN circuit board and its surroundin
s
Dark LCD Defective backlight power supply IC8 on the MAIN circuit board and its surroundings
Confirm that +5 V is put out for the output of IC8.
Defective backli
ht LED in the LCD Re
lacement of the LCD unit
Wire break in the FFC cable of the LCD
circuit board
Replacement of the LCD unit or the FFC cable
The LCD display shows incorrect
characters.
Defective connection between relay circuit
board and LCD
Connection confirmation, FFC cable replacement
Defective LCD control circuit IC1, IC9, and IC13 on the MAIN circuit board and their
surroundings
Defective LCD unit Re
lacement of the LCD unit
Some or all LEDs do not li
ht. Defective LED
arts Re
lacement of the res
ective LEDs
Defective connection between MAIN and CP Connection confirmation
FFC cable re
lacement
Defective connection between CP1 and CP3 Connection confirmation
FFC cable re
lacement
Defective connection between CP1 and CP5 Connection confirmation
cable re
lacement
Defective LED decoding circuit on the CP
circuit board
IC3101, IC3102, IC3103, IC3104, Q3101, Q3102,
Q3103, and Q3104 on the CP circuit board and their
surroundings
Defective o
eration of the UI microcom
uter IC2 on the MAIN circuit board and its surroundin
s
Related to the
power supply
Each power supply is normal, but there
is no operation.
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