Troubleshooting A Guide - NAD M22 Service Manual

No Pow er or Pow er shuts off
immediately
NO
Logo Amber LED on?
YES
Touch Pow er key
YES
NO
Logo led turn w hite?
YES
B

TROUBLESHOOTING A GUIDE

Check STB board
5V RIGHT?
YES
Check LED board
5VL RIGHT?
YES
Check Q110 Q111 Q114 Q115 Q116 circuit
Check PWM signal
Change LED board
NO
Logo led turn red?
YES
Check PSU board
+/-VB +/-VAUX +/-VDR RIGHT?
YES
Check MCU Board
VPP VPI +/-17.5V +/-VDR RIGHT?
Check MCU Board
YES
Check U104,
Check LED control signal
Change MCU board
NO check IC301 circuit
change STB board
NO
Check L104 C175 C176
Logo led turn off?
YES
Check STB board
NO
STB 3V RIGHT?
YES
Check U1 U5 PWM circuit
Change PSU Board
NO Check Q123 Q124 circuit
Change MCU Board
10
NO Check MCU board:Q131 circuit
Check STB Board:Q301 K301 circuit