Troubleshooting Guide - NAD C 355BEE Service Manual

TROUBLESHOOTING GUIDE

PUSH THE POWER SUPPLY
SWITCH TO ON
NO
IS THE AMBER LED AMBER
LIGHT?
YES
NO
CAN PRESSING ANY KEY MAKE
ARE ALL POWER SUPPLIES OK?
THE UNIT WORK NORMALLY?
YES
IS THE ABMER LED GREEN?
NO
IS THE SPK OUT NORMAL?
YES
IS THERE SIGNAL OUTPUT?
IS THE IDLE CURRENT NORMAL?
NO
IS THE REMOTE CONTROL OK? IS THE IR IN/OUT NORMAL?
YES
IS THE REMOTE HANDSET ITSELF
NORMAL?
NO
IS THE 12V SUPPLY NORMAL? IS THE 18V SUPPLY NORMAL?
YES
DID THE 12V SUPPLY SHORT
GROUND?
OK
CHECK THE AMBER LED CONTROL
CIRCUIT(Q72,Q73,Q74,LED D717)
CHECK 12V SUPPLY
NO
IS IT RED?
YES
YES
YES
NO
NO
IS THE STANDBY SINGAL LOW
LEVEL?
YES
YES
YES
SOME KEYS IS USELESS?
NO
NO
NO
IS THE OUTPUT DC LEVEL
NORMAL?
YES
NO
IS THE POWER AMP INPUT
YES
IS THE VOLUME CONTROL CIRCUIT
NORMAL?
ARE THE TWO MODULES NORMAL?
NO
IS THE THD HIGH? IS THE S/N RATE BAD?
YES
NO
YES
NO
YES
NO
YES
NO
YES
23
YES
NO
CHECK THE 5V SUPPLY CIRCUIT
IS IT GREEN?
(ON POWER BOARD)
CHECK THE LED CONTROL
CIRCUIT(Q72,Q73,Q74,LED D717)
AND PROTECET CIRCUIT
CHECK THE POWER SUPPLIES
CIRCUIT
YES
CHECK THE PROTECT CIRUIT
NO
CHECK THE STANDBY CONTROL
CIRCUIT
CHECK THE KEYS CONNECTION
CHECK MCU AND RELAY
CONTROL CIRCUIT
CHECK THE SERVO CIRCUIT
YES
CHECK THE POWER AMP CIRCUIT
NORMAL?
SECTION
NO
YES
CHECK THE MUTE CONTROL
IS THE MUTE SIGNAL OFF?
CIRCUIT
NO
NO
CHECK THE VOLUME CONTROL
CIRCUIT
YES
NO
CHECK THE MODULES CIRCUIT
YES
CHECK THE TONE CIRCUIT
YES
TURN THE TRANSFORMER
ADJUST THE IDLE CURRENT OR
CHECK THE IDLE CURRENT
CIRCUIT
CHECK THE POWER AMP CIRCUIT
(IF SOME TRANSISTORS ARE
DEFEATED)
CHECK THE IR IN/OUT
CONNECTION OR CIRCUIT(PARTS)
REPLACE THE BTTERIES OR
ANOTHER REMOTE CONTROL
HANDSET
CHECK THE IR CONTROL CIRCUIT
(INCLUDE THE IR RECEIVER AND
MCU)
CHECK THE 18V SUPPLY
CHECK THE CONNECTION
AND CHECK IF THE RELATIONAL
TRANSISTORS ARE DEFEATED