TROUBLESHOOTING A GUIDE
10
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 Regulated Supply Board
VPP VPI +/-17.5V +/-VDR RIGHT?
NO
Check Regulated Supply Board
Check Q123 Q124 circuit
YES
Check U104,
Change MCU board
Check LED control signal
Summary of Contents for M27
Page 1: ...NAD SERVICE MANUAL M27 SEVEN CHANEL M27 SEVEN CHANEL AMPLIFIER AMPLIFIER...
Page 6: ...6...
Page 26: ...1 MCU BOARD 26 PCB LAYOUT TOP Layer Bottom Layer...
Page 27: ...27 2 REGULATED SUPPLY BOARD Top Layer Bottom Layer...
Page 28: ...28 3 AMP BOARD Top Layer Bottom Layer...
Page 29: ...29 4 NC400 OEM BOARD Bottom Layer Top Layer...
Page 31: ...31 8 SMPS BOARD Bottom Layer Top Layer...
Page 32: ...32 9 SMPS STB BOARD 1 2 Bottom Layer Top Layer...
Page 33: ...33 9 SMPS STB BOARD 2 2 Bottom Layer Top Layer...
