NAD C 542 - Manual (Page 23)

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TROUBLESHOOTING GUIDE
SET POWER SWITCH TO ON.
IS POWER TURNED ON ?
CHECK FUSES
M507, M512-M514 OPEN ?
M507,M512-M514 DEFECTIVE CRYSTAL X301 DEFECTIVE.
MICROPROCESSOR IC U401 DEFECTIVE.
MOTOR DRIVE TRANSISTOR Q104,
Q105, Q106, Q107 DEFECTIVE.
CAN TRAY BE OPENED ?
CAN TRAY BE CLOSED ?
DOES INITIAL READING OCCUR ?
CAN DISC BE PLAYED ? CHECK TRACKING SERVO CIRCUIT CORRECT ? SERVO IC U101 OR U202 DEFECTIVE.
CHECK DISC OR MECHANISM AND CONNECTOR
CHECK OUTPUT PULSE AT PIN 61,62,63 OF U201
CHECK OUTPUT SIGNAL AT PIN 13,16 OF U302
AUDIO OUTPUT IS CORRECT ? IS POWER SUPPLY NORMALLY ? CHECK POWER SUPPLY PATTERNS.
OK
CHECK POWER SUPPLY
CIRCUIT NORMAL ?
IC U302 DEFECTIVE.
CHECK OUTPUT SIGNAL AT PIN 1,7 OF U305, U306 IC U305 OR U306 DEFECTIVE.
CHECK MUTE CIRCUIT Q301, Q302, Q303, Q304
LINE OUT PLUG OR PATTERNS DEFECTIVE.
MUTE CIRCUIT DEFECTIVE.
IC U201 DEFECTIVE.
M101 SWITCH, DEFECTIVE
OR PATTERN AND CONNECTOR OPEN.
IS OSCILLATOR CIRCUIT
OSCILLATING ?
POWER SUPPLY PATTERNS OPEN
OR U501-U507 DEFECTIVE.
IS THERE OPEN/ CLOSE KEY SIGNAL
INPUT ? U401 PIN 66, 65
IS LOADING MOTOR DRIVE CIRCUIT
OPERATION NORMAL ?
CHECK OPEN/ CLOSE SIGNAL AT U401
PIN 65 PIN 66
TRAY OPEN H L
TRAY CLOSE L H
LOADING MOTOR AND LEAD WIRE DEFECTIVE
OR LOADING PART OF MECHANISM DEFECTIVE.
CHECK LASER LIGHT ? DOES LENS MOVE UP AND DOWN ?
RF SIGNAL OUTPUT ?
U101 DEFECTIVE.
FEED MOTOR OR WIRING DEFECTIVE.
CHECK FOCUS SIGNAL OUTPUT ?
U101 DEFECTIVE.
CHECK CONNECTION OR PICKUP. CHECK LASER CIRCUIT CORRECT ?
CONNECTION OR PICKUP DEFECTIVE.
YES
YES
YES
YES
YES
YES
YES
YES NO
NO
NO
NO
YES
YES
YES YES YES
NO
YES YES
YES
YES
YES
YES
YES
YES
YES
NO NO NO
NO
NO NO
NO
NO
NO NO
NO
NO
NO
CHECK CLOCK PULSE AT PIN4 OF U302 M302 OR U302 DEFECTIVE.
YES
NO
NO
NO
NO
NO