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NAD
SERVICE
MANUAL
T753
T 753
Surround Sound Receiver
Surround
Sound
Receiver
DRAFT DATE: 20 FEB 2004


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2
SAFETY INFORMATION
AH VERSION
C VERSION


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3
SERVICE SAFETY PRECAUTIONS
1. Replacing the fuses
CAUTION:
FOR CONTINUED PROTECTION AGAINST THE RISK OF FIRE REPLACE ONLY WITH SAME TYPE OF
FUSE.
Reference Designator
Part Number
Description
F751*AH
33-0191001-00-88
Fuse 10A 250V Time Lag 5x20 MM UL/CSA
F751*C
33-0181006-00-88
Fuse 6.3A 250V Time Lag 5x20 MM
UL/CSA/SEMKO/VDE
F752*AH
33-0111006-00-48
Fuse 1.6A 250V Time Lag 5x20 MM
UL/CSA/VDE/SEMKO
F752*C
33-0151006-00-48
Fuse 800mA 250V Time Lag 5x20 MM
UL/CSA/VDE/SEMKO
NOTE:
<*AH > : USA, CANADIAN MODEL ONLY.
<*C >
: EUROPEAN MODEL ONLY.
2. Safety check out
(Only U.S.A. model)
Before returning the product to the customer, make leakage current or resistance measurements to determine
that exposed parts are acceptably insulated from supply circuit.
CONTENTS
DESCRIPTION
PAGE
SPECIFICATIONS ............................................................................................................................ 4 - 5
REAR PANEL / FRONT PANEL VIEW .................................................................................................. 6
DISASSEMBLY INSTRUCTIONS .......................................................................................................... 7
WIRING DIAGRAM ................................................................................................................................ 8
BLOCK DIAGRAM ................................................................................................................................. 9
SPECIAL FUNCTION .......................................................................................................................... 10
DETAILS & WAVEFORMS ON SYSTEM & TEST & DEBUGGING .................................................... 10
ADJUSTMENT POINTS DIAGRAM / AMPLIFIER ADJUSTMENT ....................................................... 11
PCB LAYOUT ............................................................................................................................... 12 - 26
SCHEMATIC DIAGRAM ............................................................................................................... 27 - 43
IC BLOCK DIAGRAM ................................................................................................................... 44 - 51
EXPLODED VIEW ........................................................................................................................ 52 - 53
EXPLODED VIEW PARTS LIST................................................................................................... 54 - 55
ELECTRICAL PARTS LIST .......................................................................................................... 56 - 68
PACKING DIAGRAM .......................................................................................................................... 69
VERSION HISTORY .......................................................................................................................... 70
Parts marked with the symbol
are critical with regard to the risk of fire and electric shock.
Replace only with parts recommended by the manufacturer.


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4
SPECIFICATIONS
POWER AMPLIFIER SECTION
Rated distortion
(Rated power level into 8 ohms, THD 20 Hz-20 kHz FL/C/FR)
0.1 %
(Rated power level into 8 ohms, THD 20 Hz-20 kHz SL/SR/BS)
0.1 %
Input Sensitivity
(ref. 8 ohms, 1 kHz)
127 ± 20 mV
S/N Ratio
(A-wtd, 1kHz, 1 W, 8 ohm, SL/SR/BL)
- 72 dB
Frequency Response
(20 Hz - 20 kHz)
0 ± 1.0 dB
Channel Balance
(1 dB to -40 dB, 1 kHz)
2 dB
(-41 dB to -50 dB, 1 kHz)
3 dB
Audio muting at 1 kHz
55 dB
Subwoofer out, 500 mV in (THD at 2 V O/P, 100 Hz)
0.5 %
Crosstalk
(500 mV input, 10 W, 1 kHz)
-57 dB
Controls
Bass
(at 500 mV in, 1 W out, 100 Hz)
± 10 dB ± 2 dB
Treble
(at 500 mV in, 1 W out, 10 kHz)
± 10 dB ± 2 dB
DOLBY DIGITAL SECTION
Channel Difference(FL ref. Track 30)
± 1.2 dB
Frequency Resporse at Dolby config.2
SL Track 46 200 - 20 kHz
± 0.8 dB
SR Track 47 200 - 20 kHz
± 0.8 dB
C Track 44 200 - 20 kHz
± 0.8 dB
Harmonic Distortion
(1 W, Audio LPF, Dolby Congfig 1)
FL Track 65 997 Hz
0.08 %
FR Track 67 997 Hz
0.08 %
SL Track 68 997 Hz
0.08 %
SR Track 69 997 Hz
0.08 %
C Track 66 997 Hz
0.08 %
S/N Ratio
(31 for O/P 1 W, Track 35)
CCIR / ARM
65 dB
Audio LPF
70 dB
A-wtd
70 dB
Channel Separation
(1 W, 20 kHz LPF)
Track 65 997 Hz
60 dB
DOLBY PRO LOGIC II SECTION
Frequency Resporse
I/P mode : L, R
: 1 V in, 1 W, Ch L/R
40 Hz
0 ± 2.0 dB
20 Hz
0 ± 2.0 dB
I/P mode : L=R
: 1 V in, 1 W, Ch /L/R
40 Hz
0 ± 2.0 dB
Ch C
20 kHz
0 ± 2.0 dB
I/P mode : L=-R
: 1 V in, 1 W, Ch SL/SR
40 Hz
0 ± 2.0 dB
20 kHz
0 ± 2.0 dB
S/N Ratio (200 mV in, 1 W, A-WTD w/ 1 k termination)
I/P mode : L, R
: 1 kHz, Ch L/R
65 dB
I/P mode : L=R
: 1 kHz, Ch C
65 dB
I/P mode : L=-R
: 1 kHz, Ch SL/SR
65 dB
THD (2.2 V in, 1 W, w/ 80 kHz LPF, 1 kHz)
0.2 %


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5
DTS SECTION
Output Level (Vol 0 dB)
: FL/FR/C/SL/SR
Track 6 1 kHz
0.3 ± 1.3 W
Channel Difference (FL ref): FL/FR/C/SL/SR
Track 6 1 kHz
± 1.0 dB
Harmonic Distortion (Audio Filter) : FL/FR/C/SL/SR
Track 10-14
1 kHz
0.08 %
Frequency Response (20 Hz to 20 kHz)
Track 26-30
+2/-1.5
Subwoofer Output Level
1 kHz ref at pre-out (FL)
Play Track 10, charge to 15
12.5 ± 1.5 dB
AM TUNER SECTION
Input level is expressed as the reading in open circuit
of 75-ohm source impedance signal generator
Usable sensitivity
(999/1000 kHz)
30 dBuV
S/N Ratio
(5 mV in)
38 dB
THD
(5 mV in)
3 %
IF Rejection
(450 kHz)
36 dB
Image Rejection
(F+2xIF)
28 dB
Selectivity
17 dB
Output
170 -20/+30 mV
Loop sensitivity
(20 dB S/N)
999/1000 kHz
66 dB
603/600 kHz
66 dB
1404/1400 kHz
66 dB
Frequency Response
(100 - 2.3 kHz, 5 mV)
± 6 dB
FM TUNER SECTION
*C
*AH
Input level is expressed as the reading in open circuit
of 75-ohm source impedance signal generator
Usable sensitivity
(98 MHz)
15 dBµV
15 dBuv
S/N Ratio
(60 dB, IHF wtd)
Mono
63 dB
63 dB
Stereo
63 dB
63 dB
Frequency Response
(20 Hz - 15 kHz, 60 dBµ)
0 ± 1.5 dB
0 ± 1.5 dB
Channel Separation
(60 dBµ)
100 Hz
30 dB
30 dB
1 k
38 dB
38 dB
10 kHz
30 dB
30 dB
Alternate Channel Selectivity (40 dBµ, ± 400 kHz)
60 dB
45 dB
Capture Ratio
(40 dBµ)
3 dB
3 dB
AM Suppression (60 dBµ, 100% Mod. FM, 30% Mod. AM)
48 dB
48 dB
Image Rejection
(119.4 MHz)
65 dB
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I.F. Rejection
(10.7 MHz)
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78 dB
Pilot Suppression
(98 MHz)
60 dB
60 dB
THD (60 dBµ, L=R 75 kHz for AH, 40 kHz Dev for C)
Mono
0.25 %
0.25 %
Stereo
0.35 %
0.35 %
Auto-Search Sensitivity
On
24 dBµ
24 dBµ
Off
15 dBµ
15 dBµ
RDS decode Sensitivity
26 dBµ
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PHYSICAL SPECIFICATIONS
Dimensions (Width x Height x Depth)
435 x 170 x 423 mm
Net Weight
20.50 Kg (45.10 lbs)
Shipping Weight
24.0 Kg (52.80 lbs)