NAD L55, Service Manual

Page: 16 / 55

2-7
Is LED On?
Check Power Circuit
Check the oscillation of X901
and Replace IC91 or X901
Check S902-S907, S909
Check Solder
Replace IC92
Check Solder
Check R904, 906, 909, 910,
R911, 916, 919, 924
Replace IC91 OK
START
Power On Check Power Circuit.
4. Front Circuit (Digitron & Key)
NO
Check Q901, Q904, D902
Check L901
YES
YES
YES
YES
YES
YES
YES YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO NO
NO
NO
NO NO
Is LED Off ?
Does bar appear
on FLD ?
Does "Main Error"
appear on FLD?
Check waveform of
IC91 Pin 14
Does all the buttons
work normally?
Does remote control
work normally?
Does waveform of
IC92 Pin 1 appear?
Is IC91 Pin 24 connected
to IC92 Pin 1 ?
Is 5V applied to
IC92 Pin 3 ?
Is 5.2V applied
to CN61 Pin 12 ?
Is HIGH State appear
on IC91 Pin 2 ?