NAD M55 - Test & Debug Flow

3-5
3. Test & debug flow
TEST
Check the AC Voltage
Power PCBA(110V or 220V)
NO
Replace power PCBA or
AC transformer.
YES
Switch on the Power PCBA
Is the DC Voltage
outputs OK?
(5V,3.3V,9V,12V,15V)
Repair or Replace Power PCBA
NO
Make sure the main PCBA don't
short on VCCs and switch it on.
YES
Is 3.3V,1.8V and 2V DC
outputs normal on main
PCBA?
Check the regulators or related diodes.
NO
YES
Insert the upgrade disc to update
the FLASH memory code.
Update FLASH
successfully?
A
YES
NO
1. Check 27MHz system clock.
2. Check system reset circuit.
3. Check FLASH R/W enable signal LOE#,WRLL.
4. Check servo related circuit.
5. Check FLASH Memory related circuit.