NAD T531AH Schematics
NOTES) Warning
NOTES) Parts that are shaded are critical
NOTES) With respect to risk of fire or
NOTES) electricial shock.
NOTES : Symbol denotes AC ground.
Symbol denotes DC chassis ground.
3-18 3-19
CIRCUIT DIAGRAM
1. POWER(SMPS) CIRCUIT DIAGRAM
IMPORTANT SAFETY NOTICE
WHEN SERVICING THIS CHASSIS, UNDER NO CIRCUMSTANCES SHOULD THE ORIGINAL DESIGN BE
MODIFIED OR ALTERED WITHOUT PERMISSION
FROM THE NAD ELECTRONICS CORPORATION. ALL
COMPONENTS SHOULD BE REPLACED ONLY WITH
TYPES IDENTICAL TO THOSE IN THE ORIGINALCIR-
CUIT. SPECIALCOMPONENTS ARE SHADED ON THE
SCHEMATIC FOR EASY IDENTIFICATION.
THIS CIRCUIT DIAGRAM MAY OCCASIONALLY DIFFER FROM THE ACTUAL CIRCUIT USED. THIS WAY,
IMPLEMENTATION OF THE LATEST SAFETY AND
PERFORMANCE IMPROVEMENT CHANGES INTO
THE SET IS NOT DELAYED UNTILTHE NEW SERVICE
LITERATURE IS PRINTED.
NOTE :
1. Shaded( ) parts are critical for safety. Replace only
with specified part number.
2. Voltages are DC-measured with a digital voltmeter
during Play mode.
Power oscillator dead.
Q101 is defective
Q101 failure caused D101 failure.
D101 is defective.
VF+ power dead.
D107 is defective.
-24VApower dead.
D108 is defective.
3.3V power dead.
IC106 and IC107 are defective.
Power control is abnormal.
Q107 and Q108 are defective.
8V Power dead.
IC105 is defective.
Power dead.
IC104 is defective.
Power dead.
IC108 is defective.
If fuse fails atstarup.
Q101 and Q102 are defective.
3-20 3-21
5
56
TRACKING LOOP
FOCUS LOOP
SLED LOOP
SPINDLE LOOP
WAVEFORM
IC204 is defective.
Scratched CD Audio abnormal.
IC203 is defective.
AD Converter Error
- No tracking/Focus control
2. DVD DSP CIRCUIT DIAGRAM
3-22 3-23
3. DRIVE & RF CIRCUIT DIAGRAM
4
1
1
6
2
3
TRACKING LOOP
FOCUS LOOP
SLED LOOP
SPINDLE LOOP
WAVEFORM
IC2A2 is defective.
No fucus & tracking control.
Q2A1, Q2A2 are defective.
CD/DVD LD will not be on.
3-24 3-25
4. MPEG CIRCUIT DIAGRAM
• NO DVD SCREEN DISPLAY
• NO VCD SCREEN DISPLAY.
• NO CD SOUND OUT.
• NO 2CH AUDIO OUT
• NO 2CH AUDIO OUT
1
7
2
4
3
5
6
WAVEFORM
IC302, IC303 are defective.
A/V out bad.
3-26 3-27
• WAVEFORMS
IC2A1 Pin 42, Focus Error
IC2A1 Pin 36, Pi
IC2A1 Pin 41
Tracking Error
IC301 Pin 139
Component Y
IC2A1 Pin 41
VBR TRACKING Error
IC2A1 Pin 57,
RF
IC201 Pin 88, SLED Drive(FMO)
IC201 Pin 18, SLED FG
IC2A1 Pin42, Focus Error(in Focus Search)
IC201 Pin 83, Focus Drive(FDO)
IC301 Pin 133, Composite IC301 Pin 151, Chrominance
(Super video out Mode)
Tek
Stop :
2.50MS/s
4 Acqs
M20.0µs
2 Apr 1999
14:47:27
Glitch
Ch1
Ch3
500mV
[T ]
T
3
IC301 Pin 145, Luminance
(Super video out Mode)
Tek
Stop :
1 00kS/s
3290 Acqs
M 500µs
CH1
280/mV
Edge Slope
Type
<Edge>
Source
Ch1
Coupling
DC
Level
280mV
Mode
&
Holdoff
3
Ch3
1.00V
[ T ]
Slope
T
IC301 Pin 159,
MPEG Clock(27MHz)
IC301 Pin 145
Component Pb
IC301 Pin 151
Component Pr
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