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C 426 SERVICE MANUAL
STEREO
AM/FM TUNER
NAD
AM/FM TUNER
STEREO
C 426
SERVICE SAFETY PRECAUTIONS
1. 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
PCB LAYOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-14
SCHEMATIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-17
IC BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-22
ELECTRICAL PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23-31
EXPLODED VIEW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
EXPLODED VIEW PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
PACKING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
-2-
SPECIFICATIONS
AM BAND SPECIFICATION
Frequency Range CA 530 - 1710 KHz Step 10 KHz
EU 531 - 1602 KHz Step 9 KHz
FREQ (KHz) UNIT LIMIT
1. Usable sensitivity 999 dBuV <= 30
(400Hz, -20dB, direct input) /1000
2. S/N RATIO 999 dB >= 38
(5mV input) /1000
3. THD (5mV input) 999 % <= 3
/1000
4. IF Rejection (450KHz) 603 dB >= 36
(ref. to item 8) /600
5. Image Rejection (F+2xIF) 1404 dB >= 25
(ref. to item 8) /1400
6. Selectivity 999 dB >= 17
(ref. to item 8) /1000
7. Output 999 mV 100 ~ 180
(30%, 10mV) /1000
8. Loop sensitivity 20dB S/N 999/1000 dB <= 68
603 / 600 dB <= 68
1404 / 1400 dB <= 68
9. Frequency response 100 - 2.3KHz 999 /1000 dB 0 +/- 6dB
(400 Hz, 5mV)
FM BAND SPECIFICATION
Frequency Range CA/EU 87.5 - 108MHz Step 50 KHz
FREQ UNIT LIMIT
1. Usable sensitivity MONO 98MHz dBu <= 15
IHF (3% THD)
2. S/N RATIO
(60dBu A filter) MONO 98MHz dB >= 72
(60dBu A filter) STEREO 98MHz dB >= 68
3. THD (60dBu Audio LPF) MONO 98MHz % < 0.4
(60dBu Audio LPF) STEREO 98MHz % < 0.6
L = R, C=40KHz Dev.
4. IF Rejection (10.7MHz) CA&EU 98MHz dB > 80
(refer to item 1)
5. Image Rejection (119.4 MHz) CA&EU 98MHz dB >= 70
(refer to item 1)
-3-
6. Capture ratio (40dBu) dB <3
7. AM Supression 98MHz dB > 60
@ 60dBu 100% mod FM, 30% mod AM
8. Pilot suppression L&R 98 MHz dB > 60
9. Frequency response 20Hz & 10KHz dB 0 +/- 1.5
( 1KHz Ref ) UL 75Us,CE50Us
10. Channel Separation @ 30 Hz dB >= 28
(60dBu IHF wtd) 1 KHz dB >= 38
10KHz dB >= 28
11. Alternate channel selectivity +/-400KHz, IHF UL dB >= 35
CE dB > 60
12. Muting level dBu 18 +/-6.
13. Output CA 98MHz mV 350~600
EU 550~900
14. RDS decode sensitivity. dBu <= 30
15. Auto-search sensitivity ON dBu <= 30
OFF dBu >= 15
16. Blend ON separation@1KHz 98MHz dB 6 +/-2
-4-
REAR PANEL / FRONT PANEL
REAR PANEL
1 2 3 4 5 6 7
1. FM ANTENNA TERMINAL 5. IR IN
2. AM ANTENNA TERMINAL 6. +12V TRIGGER IN
3. OUTPUT (L, R) 7. AC MAINS INPUT
4. RS-232
FRONT PANEL
1 2 3 4 5 6 7 8 9 10 11
1. STANDBY LED 7. MEMORY
2. STANDBY BUTTON 8. PRESET/TUNE
3. FM/AM 9. REMOTE SENSOR
4. FM MUTE/MODE 10. VFD
5. BLEND 11. PRESET/TUNE CONTROL KNOB:
6. DISPLAY
IMPORTANT NOTES
1. Show the software version
Press "DISPLAY" and "FM/AM".
2. Light UP all the icon on the VFD
Press "FM/AM" & "PRESET/TUNE".
3. Factory test resets
When VFD all Light press any key.
4. AM Step 10K/9K Change
When AM band, press "FM MUTE/MODE" & "PRESET/TUNE".
5. Shipment resets (clear)
When pressing "MEMORY" & "PRESET/TUNE" to VFD all Light, press any key.
-5-
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.
4 5
3
2
1
Figure No.1
2. Pull both sides of the TOP COVER slightly outwards 6 and tilt approx. 35