Troubleshooting Guide - NAD C 541 Service Manual

TROUBLESHOOTING GUIDE

SET POWER SWITCH TO ON.
IS POWER TURNED ON ?
YES
CAN TRAY BE OPENED ?
YES
CAN TRAY BE CLOSED ?
YES
DOES INITIAL READING OCCUR ?
YES
CAN DISC BE PLAYED ?
YES
AUDIO OUTPUT IS CORRECT ?
YES
OK
NO CHECK FUSES
M507, M512-M514 OPEN ?
YES
M507,M512-M514 DEFECTIVE
NO
IS THERE OPEN/ CLOSE KEY SIGNAL
INPUT ? U401 PIN 39, 40
NO YES
CHECK OPEN/ CLOSE SIGNAL AT U401
PIN 39
TRAY OPEN H
TRAY CLOSE L
YES
IS LOADING MOTOR DRIVE CIRCUIT
OPERATION NORMAL ? U701, PIN 2,10
YES
LOADING MOTOR AND LEAD WIRE DEFECTIVE
OR LOADING PART OF MECHANISM DEFECTIVE.
NO
CHECK LASER LIGHT ?
YES
CHECK LASER CIRCUIT CORRECT ?
YES
CONNECTION OR PICKUP DEFECTIVE.
NO
CHECK TRACKING SERVO CIRCUIT CORRECT ?
YES
CHECK DISC OR MECHANISM AND CONNECTOR
NO
IS POWER SUPPLY NORMALLY ?
YES
CHECK CLOCK PULSE AT PIN4 OF U302
YES
CHECK OUTPUT PULSE AT PIN 42,43,44 OF U301
YES
CHECK OUTPUT SIGNAL AT PIN 13,16 OF U302
YES
CHECK OUTPUT SIGNAL AT PIN 1,7 OF U305, U306
YES
CHECK OUTPUT SIGNAL AT PIN 7,1 OF U305, U306
YES
CHECK MUTE CIRCUIT Q301, Q302, Q303, Q304
YES
LINE OUT PLUG OR PATTERNS DEFECTIVE.
NO
CHECK POWER SUPPLY
CIRCUIT NORMAL ?
YES
IS OSCILLATOR CIRCUIT
OSCILLATING ?
NO
M101 SWITCH, DEFECTIVE
OR PATTERN AND CONNECTOR OPEN.
NO
PIN 40
MICROPROCESSOR IC U401 DEFECTIVE.
L
H
NO
MOTOR DRIVE IC U701 DEFECTIVE.
NO
DOES LENS MOVE UP AND DOWN ?
RF SIGNAL OUTPUT ?
FEED MOTOR OR WIRING DEFECTIVE.
NO
U101 DEFECTIVE.
NO
SERVO IC U101 OR U201 DEFECTIVE.
NO
CHECK POWER SUPPLY PATTERNS.
NO
M302 OR U302 DEFECTIVE.
NO
IC U301 DEFECTIVE.
NO
IC U302 DEFECTIVE.
NO
IC U305 OR U306 DEFECTIVE.
NO
IC U305 OR U306 DEFECTIVE.
NO
MUTE CIRCUIT DEFECTIVE.
20
NO
POWER SUPPLY PATTERNS OPEN
OR U501-U507 DEFECTIVE.
NO
CRYSTAL M401 DEFECTIVE.
NO
YES
YES
U101 DEFECTIVE.
NO
CHECK FOCUS SIGNAL OUTPUT ?
YES
CHECK CONNECTION OR PICKUP.