YES
Check STB board
Check LED board
5V RIGHT?
check IC301 circuit
NO
NO
Logo Amber LED on?
No Pow er or Pow er shuts off
immediately
5VL RIGHT?
NO
Check L104 C175 C176
YES
Check Q110 Q111 Q114 Q115 Q116 circuit
Change LED board
YES
NO
B
Touch Pow er key
Logo led turn w hite?
YES
change STB board
Check PWM signal
YES
Logo led turn off?
Logo led turn red?
YES
NO
YES
Check PSU board
+/-VB +/-VAUX +/-VDR RIGHT?
NO
Check STB board
STB 3V RIGHT?
YES
Change PSU Board
Check U1 U5 PWM circuit
NO
Check STB Board:Q301 K301 circuit
Check MCU board:Q131 circuit
YES
Check MCU Board
VPP VPI +/-17.5V +/-VDR RIGHT?
Check MCU Board
NO
Change MCU Board
Check Q123 Q124 circuit
YES
Check U104,
Change MCU board
Check LED control signal
TROUBLESHOOTING A GUIDE
10
Summary of Contents for M22
Page 1: ...NAD SERVICE MANUAL M22 STEREO AMPLIFIER M22 STEREO AMPLIFIER...
Page 6: ...6...
Page 25: ...PCB LAYOUT 1 MCU VM1 0 BOARD Top Layer Bottom Layer 25...
Page 26: ...2 2 AMP VM1 0 BOARD Top Layer Bottom Layer...
Page 27: ...2 3 NC400 OEM VM1 0 BOARD Bottom Layer Top Layer...
Page 29: ...5 SMPS VM1 0 BOARD Bottom Layer Top Layer...
Page 30: ...3 6 SMPS STB VM1 0 BOARD Bottom Layer Top Layer...