NAD C 720BEE, Service Manual

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TROUBLESHOOTING GUIDE
SWITCH THE POWER ON
IS THE AMBER LED AMBER
YES
NO
CAN PRESSING ANY KEY MAKE
OK
IS IT RED?
NO
YES
CHECK THE PROTECT
CIRCUIT
NO
CHECK THE 5V SUPPLY
CIRCUIT(ON POWER BOARD)
YES
CHECK THE AMBER LED CONTROL
IS IT GREEN?
CIRCUIT(Q701,Q702,Q703,LED701)
NO
IS THE AMBER LED RED?
YES
CHECK THE 12V POWER
SUPPLY CIRCUIT
YES
NO
NO
IS THE STANDBY
SIGNAL LOW LEVEL?
CHECK THE STANDBY
CONTROL CIRCUIT (IC704-26)
IS THE ABMER
LED GREEN?
YES
NO
IS THE VFD DISPLAY
NORMAL?
NO
IS THE VFD POWER SUPPLY
NORMAL(IC701-1,2,37,38)?
YES
YES
NO
CHECK THE VFD POWER
SUPPLY(ON POWER BOARD)
CHECK THE uPD16311 AT PIN
10,11,12,13 OF IC703
CHECK -30V AND 5V SUPPLY
SOME KEYS IS USELESS?
IS THE TUNER'S FUNCTION
NORMAL?
YES
NO
IS THE SEARCH FUNCTION
NORMAL?
CHECK THE ANTENNA
CHECK THE
CONNECTERS OF TUNER
IS THE REMOTE DEVICE
NO
YES
CHECK THE IR RECEIVE CIRCUIT
IS THE SPK OUT NORMAL?
IS THE CONTROL SIGNAL
OF SPK A&B NORMAL?
YES NO
NO
CHECK THE CONTROL CIRCUIT
(IC32-4&5 OR RL12/1&RL12/2 )
IS THE PRE-OUT NORMAL?
YES
NO
CHECK THE POWER AMP
CIRCUIT SECTION
IS THE MUTE SIGNAL OFF?
YES
CHECK THE MUTE CONTROL
CIRCUIT (IC32-7)
NO
IS THE SELECTED INPUT
RELAY ON?
NO
YES
CHECK THE CONTROL CIRCUIT
(IC33-4,5,6,7,13,14)
CHECK THE PRE AMP CIRCUIT IS THE VOLUME CONTROL
CIRCUIT NORMAL?
(NOTE THE IN/OUT MODULES)
CHECK THE VOLUME
CONTROL CIRCUIT
IS THE POWER
SUPPLY LOWER THAN THE
LOWERST WORK VOLTAGE?
NO
CHECK THE POWER SUPPLY
IS THE SPK OUT NOTING ?
CHECK THE PRE-IN SIGNAL
YES
NO
IS THE ZONE 2 OUT NORMAL?
YES
CHECK IC31(NOTE THE +/-16V
SUPPLY AND PIN 14,15,16 )
IS THE SUB OUT NORMAL?
YES
NO
CHECK THE SUB OUT CIRCUIT
(NOTE IC34 AND Q310)
THE UNIT WORK NORMALLY?
YES
THE uPD16311(IC703) IS
NO
YES
NO
YES
NO
YES
OF uPC16311(IC703-14,33,34,35)
NO
SPECIAL FUNCTION
TUNER SECTION
Simultaneously press ''FM''+"CD": C -version (230V) factory reset
Simultaneously press ''FM''+"DISC": AH -version (120V) factory reset
Simultaneously press ''FM''+"AM": displays software version
Press "AM"+"TAPE": all icons in the VFD DISPLAY light up
In addition, in tuner mode, press the "MEMORY" key on ce , and then press the "DISPLAY" key o nce .This will
allow you to change the current display ; to a familiar name, a nd it can be stored with the "MEMORY" key.
DEFECTIVE
LIGHT?
NORMAL?
YES
YES
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