NAD C-730 Service manual
NAD
SER VICE MANUAL
C 730
STEREO
RECEIVER
C 730
STEREO
RECEIVER
2
SERVICE SAFETY PRECAUTIONS
1. Replacing the fuses
CAUTION: FOR CONTINUED PROTECTION AGAINST THE RISK OF FIRE REPLACE ONLY
WITH SAME TYPE OF FUSE.
Reference No Part Number Description
M151 *AH 5120-0037-0 FU T3.15A 250V UL/CSA 5X20MM
M152 *C 5100-2530-1B T2.5A/250V IEC
M154 *AH 5120-0052-0 FUSE T1.6A 250V 5X20MM UL/CSA
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 the supply circuit.
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.
CONTENTS
DESCRIPTION PAGE
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4
REAR PANEL / FRONT PANEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
DISASSEMBLY INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
ADJUSTMENT POINTS DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
INSTRUMENT SETUP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
ALIGNMENT PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-11
IMPORTANT NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
PCB LAYOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-14
SCHEMATIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15-19
IC BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-23
ELECTRICAL PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24-33
EXPLODED VIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
EXPLODED VIEW PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35-36
PACKING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
3
SPECIFICATIONS
POWER AMPLIFIER SECTION
1. Rated Distortion
(THD 20Hz-20KHz, 30W, 8 ohm) ≤0.08%
(THD 1KHz, 30W, 4 ohm) ≤0.1%
2. Input Sensitivity (ref. 30W 8 ohm, 1KHz) 350+/-30mV
3. S/N Ratio (A-wtd, 1K ohm, 500mV CD in, 1KHz) ≥-85dB
4. Frequency Response (500mV CD in, 1W, 20Hz-20KHz) 0±0.8dB
5. Channel Balance
Volume maximal output 30W (ref), 1KHz ≤1dB
1dB to -40dB, 1KHz ≤2dB
-41dB to -50dB, 1KHz ≤3dB
6. Audio Muting at 1KHz ≥-52dB
7. Headphone Output in 0.1% (600 ohm load, 500mV CD in, 1KHz) ≥10V
8. Crosstalk (2V input, 10W, 1KHz) ≤-63dB
PRE - AMPLIFIER SECTION
1. Rated Distortion (THD, 2V CD input, 4V output, 1KHz) ≤0.08%
2. Frequency Response (500mV CD in, 20Hz-20KHz) 0±0.08dB
3. S/N Ratio (A-wtd, 500mV CD in, 1KHz) ≥-85dB
4. Tone Control Response
Bass (500mV in,1W out ,100Hz) boost / cut 9±2dB
Treble (500mV in,1W out ,10KHz) boost / cut 9±2dB
AM TUNER SECTION
Frequency Range: AH 530 - 1710 KHz Step 10 KHz
C 531 - 1602 KHz Step 9 KHz
Input level is expressed as the reading in open-circuit
of 75-ohm source impedance signal generator.
1. Usable Sensitivity (999/1000KHz) ≤30dBµV
2. S/N Ratio (5mV input) ≥38dB
3. THD (5mV input) ≤3%
4. IF Rejection (450KHz) ≥36dB
5. Image Rejection (F+2xIF) ≥28dB
6. Selectivity ≥17dB
7. Output 130mV±26mV
8. Loop Sensitivity (20dB S/N) 999/1000KHz ≤66dB
603/600KHz ≤66dB
1404/1400KHz ≤66dB
9. Frequency Response (100-2.3KHz, 5mV) 0±6dB
4
FM TUNER SECTION
Frequency Range: AH 87.5 - 108 MHz Step 50 KHz
C 87.5 - 108 MHz Step 50 KHz
Input level is expressed as the reading in open-circuit
of 75-ohm source impedance signal generator.
*C *AH
1. Usable Sensitivity (Mono, 98MHz) ≤15dBµ ≤15dBµ
2. S/N Ratio (60dBµ, IHF wtd) Mono ≥72dB ≥72dB
Stereo ≥66dB ≥66dB
3. THD (60dBµ, L=R, 75KHz Dev. for AH, 40KHz Dev. for C)
Mono ≤0.3% ≤0.3%
Stereo ≤0.35% ≤0.35%
4. IF Rejection (10.7MHz) ≥78dB ≥65dB
5. Image Rejection (119.4MHz) ≥85dB ≥85dB
6. Capture Ratio (40dBµ) ≤3dB ≤3dB
7. AM Suppression (60dBµ, 100%mod FM, 30%mod AM) ≥48dB ≥48dB
8. Pilot Suppression (60dBµ) ≥60dB ≥60dB
9. Frequency Response
(60dBµ, 20Hz - 15KHz in, 75µS for AH, 50µS for C and 0±1.5dB 0±1.5dB
Japan)
10. Channel Separation (60dBµ, IHF wtd) 100Hz ≥30dB ≥30dB
1KHz ≥38dB ≥38dB
10KHz ≥30dB ≥30dB
11. Alternate Channel Selectivity (±400KHz, IHF) ≥60dB ≥45dB
12. Muting Level 18±3dBµ 18±3dBµ
13. Output 750mV±150mV 500mV±100mV
14. Blend on Separation (60dBµ IHF wtd) 6±2dB 6±2dB
15. RDS Decode Sensitivity ≤26dBµ ≤26dBµ
16. Auto-search Sensitivity OFF ≤15dBµ ≤15dBµ
ON ≤24dBµ ≤24dBµ
PHYSICAL SPECIFICATIONS
Dimensions (Width x Height x Depth) 435 x 109 x 305 mm
Net weight 7.2 kg (15.87 lbs)
Shipping weight 9.2 kg (20.5 lbs)
5
REAR PANEL / FRONT PANEL
REAR PANEL
FRONT PANEL
1. POWER ON / OFF
2. STAND-BY INDICATOR
3. BLEND
4. MEMORY
5. FM MUTE / MODE
6. AM / FM
7. DISPLAY
8. PRESET / TUNE
9. PRESET / TUNE AND
10. DISPLAYAREA
11. VOLUME
12. HEADPHONE SOCKET
13. INPUT SELECTORS
14. BASS & TREBLE
15. TONE DEFEAT
16. BALANCE
1. FM ANTENNA
2. AM ANTENNA
3. DISC INPUT
4. CD INPUT
5. VIDEO INPUT
6. AUX INPUT
7. TAPE 2 IN, OUT
8. TAPE 1 IN, OUT
9. PRE OUT
10. NAD-LINK IN, OUT
11. SOFT CLIPPING
12. 12V TRIGGER OUT
13. SPEAKERS
14. AC LINE CORD
15. SWITCHED AC OUTLET (AH version only)
6
DISASSEMBLY INSTRUCTIONS
1. Remove machine screws M 4.0 x 6.0 ( 1 to 4 ) from the side panels.
Remove tapping screw 3.0 x 8.5 ( 5 ) from the back panel.
Refer to Figure No.1.
Figure No.1
2. Pull both sides of the TOP COVER slightly outwards 6 and tilt approx. 35˚ and then remove
in the direction as indicated by the arrow 7 . Refer to Figure No.2.
Figure No.2.
5
4
3
1
2
7
6
6
7
BLOCK DIAGRAM
TUNER
IN
AUDIO
OUT
LA1837
AM/FM IF
FRONT END
VT
ENV172D3G1
AC INPUT
RELAY
AUDIO IN
LC72723M
TUNE
ST/MO, MUTE, SMETER
data
AM
OSC/IF
LC7218
FM
OSC/IF
PLL
VT
MAIN
POWER
SUPPLY
DIODE
MATRIX
IN-OUT
NAD LINK
OUT
SPEAKER
RELAY
AMP.
POWER
AC INPUT
POWER
SUPPLY
STAND BY
Protect
+5V CPU
MUTE
out
ce data clk RDS-CLK RDS-SIG RDS-DATA
CPU
(#1)=Power On
(#2)=Protect (Flash 2Hz)
(#1)+(#2)=Standby
VFD
VOLUME
MOTORIZE
AM LOOP ANT FM ANT
Locking SW,
Tone defeat
Trigger Out
KEY MATRIX
SENSOR
REMOTE
CD
DISC
VIDEO
(#1)
(#2)
TC9273
S1 1
S2S3S4S5S6S7S8S9S10
AUX
OUT
TAPE-1
TAPE-2
OUT
IN
TAPE-2
L R
12 17
PRE OUT
TAPE-1
IN (Mon)
8
WIRING DIAGRAM
3PIN BLACK
35PIN BLACK
P39 P40 P41 P42 P43 P44 P45 P46 P47 P48
SECONDARY BOARD
TRANSFORMER
3PIN BLACK
P33 P34 P35 P36
P32
PRIMARY BOARD
KEY BOARD
BROWN
RED
BLUE
BLUE
LED BOARD
4PIN BLACK
PSU BOARD
AC INPUT
POWER SWITCH BOARD
TUNER BOARD
BLACK
SPEAKER BOARD
3PIN BLACK
6PIN BLACK
MAIN BOARD
BLACK
6PIN BLACK
BLACK
PHONE BOARD
BLUE
GREEN
OSC RF
Testing
Point
TP2
Testing
Point
TP1
Testing
Point
TP3
Testing
Point
TP4
9
ADJUSTMENT POINTS DIAGRAM
1. TUNER
2. MAIN BOARD
FM
SIGNAL
GENERATOR
OUTPUT
TERMINAL
OUTPUT
TERMINAL
DISTORTION
ANALYZER
DISTORTION
ANALYZER
AC
VOLTMETER
OSCILLOSCOPE
AC
VOLTMETER
OR
OSCILLOSCOPE
AC
VOLTMETER
OR
OSCILLOSCOPE
OUTPUT
TERMINAL
OUTPUT
TERMINAL
L
R
ANTENNA
TERMINAL
ANTENNA
TERMINAL
ANTENNA
TERMINAL
AM LOOP
ANTENNA
(Accessory)
AM LOOP
ANTENNA
60cm
DIGITAL
MILLIVOLT
METER
VT
J911,
GND
FM
SIGNAL
GENERATOR
AM
SIGNAL
GENERATOR
FM
SIGNAL
GENERATOR
RDS
GENERATOR
FM
STEREO
GENERATOR
P901
DC
MILLIVOLT
METER
UNIT
UNIT
UNIT
UNIT
INSTRUMENT SETUP
1. FM MEASUREMENT
Fig. 1
Fig. 2
2. RDS MEASUREMENT
Fig. 3
3. AM MEASUREMENT
Fig. 4
10
ALIGNMENT PROCEDURES
AMPLIFIER SECTION
Step Item Connection Adjustment Adjust for
1 Left Channel Voltmeter to TP1, TP2 on Amp Board R868 2mV±0.2mV
2 Right Channel Voltmeter to TP3, TP4 on Amp Board R867 2mV±0.2mV
11
FM/RDS SECTION
INPUT
- FM mono: 1kHz, 75kHz devi., 60dB/µV
- FM stereo: 1kHz, 67.5kHz devi., 60dB/µV
Pilot signal 19kHz 7.5kHz devi.
OUTPUTS
- Connect the non-inductive type resistor of 8 ohms to all
speaker terminals otherwise noted.
Item
FM
IF/RF
Stereo
Distortion
Stereo
Separation
Muting
Level
Signal
output
Step
1
DC voltmeter L941
0±100mV
3
Distortion
analyzer
Distortion
analyzer
Oscilloscope
Oscilloscope
L942
R956
R941
Minimum
Minimum
2 AC voltmeter
IFT on the
front end
IFT on the
front end
Maximum
Maximum
separation
Connection
of instrument
Fig.1 –
–
Fig.2
Fig.2
Fig.1
Channel L
or R 1kHz
99.0MHz
1kHz 75kHz devi.
65dBf (60dB)
99.0MHz Ext.
mod. 65dBf
(60dB)
FM SG
output
Stereo modulator output
Tuning
frequency
99.0MHz
99.0MHz
Channel L
or R 1kHz
99.0MHz Ext.
mod. 65dBf
(60dB)
99.0MHz
mod. 65dBf(60dB)
RDS 2% MOD
99.0MHz
1KHz 75KHz devi
33dBµ
99.0MHz
mod.65dBf(60dB)
99.0MHz 18dB
99.0MHz
99.0MHz
Pilot
Suppression
Signal
Strength
Indicator
RDS
MIN
7 bars just
lit
VTVM
VFD Signal
Bars
L903 FOR L
L904 FOR R
R991
Channel L or
R pilot on
signal
–
Fig.2
Fig.1
Fig.3
99.0MHz
99.0MHz
–
– – –
99.0MHz
Output
indicator
Adjustment
point
Adjust
for
Remarks
FM MUTE/MODE
switch: ON/AUTO
Repeat the steps
1 to 3 until no further adjustment is
necessary.
FM MUTE/MODE
switch: ON/AUTO
Don’t turn more
than +/-180˚
Repeat stereo
distortion and
stereo separation
alignment until
THD at minimum
and separation at
maximum.
Adjust such that
output just unmute
Decode the RDSprogram station
AM SECTION
AM Modulation: 400Hz, 30%
For AH Version
Step
1 –
2
3
530kHz
600kHz
990kHz
600kHz
400Hz 30% mod.
60dB/m
AM SG
output
Tuning
frequency
Output
indicator
Adjustment
point
600kHz
400Hz 30% mod.
60dB/m
AC
voltmeter
AC
voltmeter
Digital
DC
voltmeter
L972
OSC coil
on RF
block M971
RF coil
on RF
block M971
Adjust
for
1.35±0.2V
Maximum
Maximum
Step
1 –
2
3
522kHz
or
531kHz
603kHz
999kHz
600kHz
400Hz 30% mod.
60dB/m
AM SG
output
Tuning
frequency
Output
indicator
Adjustment
point
600kHz
400Hz 30% mod.
60dB/m
AC
voltmeter
AC
voltmeter
Digital
DC
voltmeter
L972
OSC coil
on RF
block M971
RF coil
on RF
block M971
Adjust
for
1.3±0.2V (522kHz)
1.35±0.2V (531kHz)
Maximum
Maximum
For C Version
IMPORTANT NOTES
1. Show the software version
Press “PRESET/TUNE” and
“TUNE UP”.
2. Light UP all the icon on the
VFL
Press “PRESET/TUNE” and
“TUNE DOWN”.
3. CPU Resets
Press “PRESET/TUNE” and
“TUNE DOWN” and any one
key.
4. AM Step 10K/9K Change
Add or delete the AM step
jumper - J201 in the key PCB.
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