NAD L-76 Service manual

SERVICE MANUAL

L76

A/V RECEIVER

L76

A/V RECEIVER

1-3

SECTION 1

SUMMARY

CONTENTS

PRODUCT SAFETY SERVICING GUIDELINES.......................................................................................... 1-4

SERVICING PRECAUTIONS ....................................................................................................................... 1-5

* General Servicing Precautions

* Insulation checking prodedure

* Electrostatically Sensitive Devices

SPECIFICATIONS ......................................................................................................................................... 1-6

LOCATION OF CUSTOMER CONTROLS ......................................................................................... 1-7 ~ 1-8

EXPLODED VIEW ............................................................................................................................. 1-9 ~ 1-10

1-4

PRODUCT SAFETY SERVICING GUIDELINES

CAUTION : DO NOT ATTEMPT TO MODIFY THIS PRODUCT IN ANY WAY. NEVER PERFORM CUSTOMIZED INSTALLATIONS WITHOUT MANUFACTURER’S APPROVAL. UNAUTHORIZED MODIFICATIONS WILL NOT ONLY VOID THE WARRANTY, BUT MAY LEAD TO YOUR BEING LIABLE FOR ANY RESULTING PROPERTY DAMAGE OR USER INJURY.

SERVICE WORK SHOULD BE PERFORMED ONLY AFTER YOU ARE THOROUGHLY FAMILIAR WITH ALL OF THE FOLLOWING SAFETY CHECKS AND SERVICING GUIDELINES. TO DO OTHERWISE, INCREASES THE RISK OF POTENTIAL HAZARDS AND INJURY TO THE USER.

WHILE SERVICING, USE AN ISOLATION TRANSFORMER FOR PROTECTION FROM AC LINE SHOCK.

SAFETY CHECKS

AFTER THE ORIGINAL SERVICE PROBLEM HAS BEEN CORRECTED. A CHECK SHOULD BE MADE OF THE FOLLOWING.

SUBJECT : FIRE & SHOCK HAZARD

1. BE SURE THAT ALL COMPONENTS ARE POSITIONED IN SUCH A WAY AS TO AVOID POSSIBILITY OF ADJACENT COMPONENT SHORTS. THIS IS ESPECIALLY IMPORTANT ON THOSE MODULES WHICH ARE TRANSPORTED TO AND FROM THE REPAIR SHOP.

2. NEVER RELEASE A REPAIR UNLESS ALL PROTECTIVE DEVICES SUCH AS INSULATORS, BARRIERS, COVERS, SHIELDS, STRAIN RELIEFS, POWER SUPPLY CORDS, AND OTHER HARDWARE HAVE BEEN REINSTALLED PER ORIGINAL DESIGN. BE SURE THAT THE SAFETY PURPOSE OF THE POLARIZED LINE PLUG HAS NOT BEEN DEFEATED.

3. SOLDERING MUST BE INSPECTED TO DISCOVER POSSIBLE COLD SOLDER JOINTS, SOLDER SPLASHES OR SHARP SOLDER POINTS. BE CERTAIN TO REMOVE ALL LOOSE FOREIGN PARTICLES.

4. CHECK FOR PHYSICAL EVIDENCE OF DAMAGE OR DETERIORATION TO PARTS AND COMPONENTS. FOR FRAYED LEADS, DAMAGED INSULATION (INCLUDING AC CORD). AND REPLACE IF NECESSARY FOLLOW ORIGINAL LAYOUT, LEAD LENGTH AND DRESS.

5. NO LEAD OR COMPONENT SHOULD TOUCH A RECEIVING TUBE OR A RESISTOR RATED AT 1 WATT OR MORE. LEAD TENSION AROUND PROTRUDING METAL SURFACES MUST BE AVOIDED.

6. ALL CRITICAL COMPONENTS SUCH AS FUSES, FLAMEPROOF RESISTORS, CAPACITORS, ETC. MUST BE REPLACED WITH EXACT FACTORY TYPES, DO NOT USE REPLACEMENT COMPONENTS OTHER THAN THOSE SPECIFIED OR MAKE UNRECOMMENDED CIRCUIT MODIFICATIONS.

7. AFTER RE-ASSEMBLY OF THE SET ALWAYS PERFORM AN AC LEAKAGE TEST ON ALL EXPOSED METALLIC PARTS OF THE CABINET, (THE CHANNEL SELECTOR KNOB, ANTENNA TERMINALS. HANDLE AND SCREWS) TO BE SURE THE SET IS SAFET TO OPERATE WITHOUT DANGER OF ELECTRICAL SHOCK. DO NOT USE A LINE ISOLATION TRANSFORMER DURING THIS TEST USE AN AC VOLTMETER, HAVING 5000 OHMS PER VOLT OR MORE SENSITIVITY, IN THE FOLLOWING MANNER; CONNECT A 1500 OHM 10 WATT RESISTOR, PARALLELED BY A .15 MFD, 150V AC TYPE CAPACITOR BETWEEN A KNOWN GOOD EARTH GROUND (WATER PIPE, CONDUIT, ETC.) AND THE EXPOSED METALLIC PARTS, ONE AT A TIME. MEASURE THE AC VOLTAGE ACROSS THE COMBINATION OF 1500 OHM RESISTOR AND .15 MFD CAPACITOR. REVERSE THE AC PLUG AND REPEAT AC VOLTAGE MEASUREMENTS FOR EACH EXPOSED METALLIC PART.

VOLTAGE MEASURE MUST NOT EXCEED 75 VOLTS R.M.S. THIS CORRESPONDS TO 0.5 MILLIAMP AC ANY VALUE EXCEEDING THIS LIMIT CONSTITUTES A POTENTIAL SHOCK HAZARD AND MUST BE CORRECTED IMMEDIATELY.

SUBJECT : GRAPHIC SYMBOLS

SUBJECT : TIPS ON PROPER INSTALLATION

1. NEVER INSTALL ANY PRODUCT IN A CLOSED-IN RECESS, CUBBYHOLE OR CLOSELY FITTING SHELF SPACE. OVER OR CLOSE TO HEAT DUCT, OR IN THE PATH OF HEATED AIR FLOW.

2. AVOID CONDITIONS OF HIGH HUMIDITY SUCH AS: OUTDOOR PATIO INSTALLATIONS WHERE DEW IS A FACTOR, NEAR STEAM RADIATORS WHERE STEAM LEAKAGE IS A FACTOR, ETC.

3. AVOID PLACEMENT WHERE DRAPERIES MAY OBSTRUCT REAR VENTING. THE CUSTOMER SHOULD ALSO AVOID THE USE OF DECORATIVE SCARVES OR OTHER COVERINGS WHICH MIGHT OBSTRUCT VENTILATION.

4. WALL AND SHELF MOUNTED INSTALLATIONS USING A COMMERCAL MOUNTING KIT MUST FOLLOW THE FACTORY APPROVED MOUNTING INSTRUCTIONS A PRODUCT MOUNTED TO A SHELF OR PLATFORM MUST RETAIN ITS ORIGINAL FEET (OR THE EQUIVALENT THICKNESS IN SPACERS) TO PROVIDE ADEQUATE AIR FLOW ACROSS THE BOTTOM, BOLTS OR SCREWS USED FOR FASTENERS MUST NOT TOUCH ANY PARTS OR WIRING. PERFORM LEAKAGE TEST ON CUSTOMIZED INSTALLATIONS.

5. CAUTION CUSTOMERS AGAINST THE MOUNTING OF A PRODUCT ON SLOPING SHELF OR A TILTED POSITION, UNLESS THE PRODUCT IS PROPERLY SECURED.

6. A PRODUCT ON A ROLL-ABOUT CART SHOULD BE STABLE ON ITS MOUNTING TO THE CART. CAUTION THE CUSTOMER ON THE HAZARDS OF TRYING TO ROLL A CART WITH SMALL CASTERS ACROSS THRESHOLDS OR DEEP PILE CARPETS.

7. CAUTION CUSTOMERS AGAINST THE USE OF A CART OR STAND WHICH HAS NOT BEEN LISTED BY UNDERWRITERS LABORATORIES, INC. FOR USE WITH THEIR SPECIFIC MODEL OF TELEVISION RECEIVER OR GENERICALLY APPROVED FOR USE WITH T.V.’S OF THE SAME OR LARGER SCREEN SIZE.

8. CAUTION CUSTOMERS AGAINST THE USE OF EXTENSION CORDS, EXPLAIN THAT A FOREST OF EXTENSIONS SPROUTING FROM A SINGLE OUTLET CAN LEAD TO DISASTROUS CONSEQUENCES TO HOME AND FAMILY.

THE LIGHTNING FLASH WITH ARROWHEAD SYMBOL, WITHIN AN EQUILATERAL TRIANGLE, IS INTENDED TO ALERT THE USER TO THE PRESENCE OF UNINSULATED “DANGEROUS VOLTAGE” WITHIN THE PRODUCT’S ENCLOSURE THAT MAY BE OF SUFFICIENT MAGNITUDE TO CONSTITUTE A RISK OF ELECTRIC SHOCK.

THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THE USER TO THE PRESENCE OF IMPORTANT OPERATING AND MAINTENANCE (SERVICING) INSTRUCTIONS IN THE LITERATURE ACCOMPANYING THE APPLIANCE.

1-5

SERVICING PRECAUTIONS

CAUTION : Before servicing the A/V Receiver covered by this service data and its supplements and addends, read and follow the SAFETY PRECAUTIONS. NOTE : if unforeseen circumstances create conflict between the following servicing precautions and any of the safety precautions in this publication, always follow the safety precautions.

Remember Safety First:

General Servicing Precautions

1. Always unplug the A/V Receiver AC power cord from the AC power source before: (1) Removing or reinstalling any component, circuit board,

module, or any other assembly.

(2) Disconnecting or reconnecting any internal electrical plug or

other electrical connection.

(3) Connecting a test substitute in parallel with an electrolytic

capacitor.

Caution : A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in an explosion hazard.

2. Do not spray chemicals on or near this A/V Receiver or any of its assemblies.

3. Unless specified otherwise in this service data, clean electrical contacts by applying an appropriate contact cleaning solution to the contacts with a pipe cleaner, cottontipped swab, or comparable soft applicator. Unless specified otherwise in this service data, lubrication of contacts is not required.

4. Do not defeat any plug/socket B+ voltage interlocks with which instruments covered by this service manual might be equipped.

5. Do not apply AC power to this A/V Receiver and/or any of its electrical assemblies unless all solid-state device heat sinks are correctly installed.

6. Always connect test instrument ground lead to the appropriate ground before connecting the test instrument positive lead. Always remove the test instrument ground lead last.

Insulation Checking Procedure

Disconnect the attachment plug from the AC outlet and turn the power on. Connect an insulation resistance meter(500V) to the blades of the attachment plug. The insulation resistance between each blade of the attachment plug and accessible conductive parts (Note 1) should be more than 1M-ohm. Note 1 : Accessible Conductive Parts including Metal panels, Input terminals, Earphone jacks, etc.

Electrostatically Sensitive (ES) Devices

Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive (ES) Devices. Examples of typical Es devices are integrated circuits and some field effect transistors and semiconductor chip components. The following techniques should be used to help reduce the incidence of component damage caused by static electricity.

1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging wrist strap device, which should be removed for potential shock reasons prior to applying power to the unit under test.

2. After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.

3. Use only a grounded-tip soldering iron to solder or unsolder ES devices.

4. Use only an antistatic solder removal device. Some solder removal devices not classified a “anti-static” can generate electrical charges sufficient to damage ES devices.

5. Do not use freonpropelled chemicals. These can generate electrical charge sufficient to damage ES devices.

6. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most replacement ES devices are packaged with leads electrically shorted together by conductive foam, aluminum foil, or comparable conductive material).

7. lmmediately before removing the protective material from the leads of a replacement ES device, touch the protective material to the chassis or circuit assembly into which the device will be installed.

Caution : Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.

8. Minimize bodily motions when handing unpackaged replacement ES devices. (Normally harmless motion such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity sufficient to damage an ES device.)

1-6

SPECIFICATIONS

Amplifier Section

Output Power (Front) :

F.T.C Rating: 60 watts RMS per channel minimum, both channels driven into 8 ohms from 20 Hz to 20kHz with no more than 0.09% total harmonic distortion

Surround Output Power (0.5% THD, 1 kHz, 8 ohms) :

40 + 40 Watt (Front) 40 Watt (Center) 40 + 40 Watt (Rear)

Total Harmonic Distortion (Front) :

0.02 % (at 60 watts, 1 kHz)

Delay Time :

DOLBY DIGITAL : REAR : 0 - 15 ms

CENTER : 0 - 5 ms

DOLBY PRO LOGIC : MOVIE : 10 - 25 ms

MUSIC : 0 - 15 ms EMULATION : 10 - 25 ms

Audio Input Sensitivity/Impedance :

*LINE : 200 mV/47 k ohms

Output Level / Impedance :

TAPE REC : 185 mV/2.2 k ohms

Frequency Response :

*LINE : 20 Hz - 65 kHz, +1/ -3 dB

Signal-to-Noise Ratio : 1 Watt

*LINE : 70 dB (IHF-A)

Tone Control :

BASS : ±10 dB at 100 Hz TREBLE : ±10 dB at 10 kHz

Digital Audio Section

Sampling Frequency :

32 kHz, 44.1 kHz, 48 kHz

DIGITAL Input Level/Impedance

COAXIAL : 0.5 Vp-p/75 ohms OPTICAL : -15 dBm ~ -21 dBm

ideo Section

Input Sensitivity /Impedance : 1.0 Vp-p/75 ohms Output Level /Impedance : 1.0 Vp-p/75 ohms

*LINE means TAPE, AUX, VIDEO 1, VIDEO 2, DVD

Improvements may result in specifications and features

changing without notice. lllustrations may differ slightly from production models.

FM Tuner Section

(Without notes 100.1 MHz, 65 dBf)

Tuning Range :

87.5 MHz - 108.0 MHz : 50 kHz steps

AM Suppression Ratio: 45 dB

Total Harmonic Distortion (1 kHz) :

Mono : 0.4% Stereo : 0.5%

Frequency Respones : 30 Hz - 15 kHz, +1/ -1. 5 dB Stereo Separation (1 kHz) : 40 dB

Signal-to-Noise Ratio :

Mono : 75 dB Stereo : 70 dB

AM Tuner Section

Tuning Range: 522 kHz - 1,620 kHz (9 kHz steps)

Usable Sensitivity : 55 dB/m Total Harmonic Distortion : 0.8% at 85 dB/m Signal-to-Noise Ratio : 45 dB at 85 dB/m

General

Power Requirements : 230V AC, 50Hz Power Consumption : 1.2A

Dimensions (W x H x D) : 285 x 133 x 348 Weight (net) : 8.8kg

1-7

LOCATION OF CUSTOMER CONTROLS

FRONT PANEL

REAR PANEL

POWER STANDBY/ON button

VFL Display

PHONES

S-VIDEO Signal jacks

BASS/TREBLE Tone Controls

AUDIO Signal jacks

BALANCE Control

MASTER VOLUME Control

Dolby Digital / DTS / PCM DIGITAL IN jacks

SOURCE SELECTOR Control

VIDEO Signal jacks

PRE OUT jack

SPEAKER terminals

DIGITAL OUT jacks

1-8

VFL DISPLAY

REMOTE CONTROL

1. POWER ON/OFF button (L76/L56)

2. DEVICE SELECTOR buttons

3. PROGRAM buttons (L56)

4. CLEAR button (L56)

5. REPEAT button (L56)

6. INPUT SOURCE SELECTOR buttons(L76), NUMERIC buttons (L76/L56)

7. OSD ON/OFF buttons (L76), DVD SET UP button (L56)

8. MUTE button (L76)

9. PRESET UP/DOWN buttons (L76), SLOW buttons (L56)

10. TEST TONE button (L76), ZOOM button (L56)

11. SURROUND MODE button (L76), RANDOM button (L56)

12. VOLUME UP/DOWN buttons (L76)

13. AM button (L76), TITLE button (L56)

14. FM button (L76), MENU button (L56)

15. ARROW buttons (L76/L56)

16. ENTER button (L76/L56)

17. DIGITAL INPUT/ RDS button (L76), DVD DISPLAY button (L56)

18. SLEEP button (L76), RETURN button (L56)

19. OPEN/CLOSE button (L56)

20. STOP button (L56)

21. PAUSE button (L56)

22. REV SCAN/SKIP button (L56)

23. PLAY button (L56)

24. FOR SCAN/ SKIP button (L56)

25. SURROUND LEVEL UP/DOWN buttons (L76)

26. CENTER LEVEL UP/DOWN buttons (L76)

27. SUBWOOFER LEVEL UP/DOWN buttons (L76)

SURROUND MODE indicator

DEVICE SELECTOR

AMP

TUNER

TAPE

PROGRAM

SETUP

SLOW

PRESET

SLOW

TITLE

DISP

SURR.

DVD

AUX

10+

 



DVD

CAB/SAT

VCR

CLEAR

VIDEO 1

TAPE

/ZOOM

TV/VIDEO

TEST

LEARN

RANDOM

SURR. MODE

ENTER

CHANNEL VOLUME

CENTER

HTR L76

OFF

MACRO

REPEAT

VIDEO 2

TUNER

MUTE

VOL

SLEEP

RTN

SUB

TUNED indicator

INPUT SOURCE, FREQUENCY, LEVEL indicator

RDS indicator

MEMORY indicator

TUNER MUTE indicator

DELAY TIME, PRESET CHANNEL indicator

EXPLODED VIEW

DESCRIPION

AL PANEL

SIDE BAR RUBBER , TRANS KHG1A198 2

VOLUME KNOB ASS'Y

VOLUME KNOB ASS'Y(B)

VOLUME KNOB ASS'Y(A)

6 7

WINDOW,FIP

INDICATOR,POWER

KNOB, DISPLAY

KNOB, POWER

WINDOW, SENSOR

PANEL, SUB

FAN

COVER, FAN CMH1A117

SINK, HEAT(F)

SINK, HEAT(R) CMY1A116 17 18

FOOT 19

FOOT CUSHION 20

PCB MOUNT CHE1A023 6 21

HOLDER, PCB 1 22

PANEL , REAR

AC CORD

AC CORD BUSHING 25

TOP CABINET 26

LOCKER C:KRE1A037 10

27 28 29

PCB , AUDIO INPUT 30

PCB , VIDEO INPUT 31

PCB , SVIDEO INPUT 32

PCB , GUIDE 33 34

PCB , SURROUND CUP11550-1/2

PCB , FRONT AMP CUP11397-1 36

PCB , SURROUND AMP CUP11397-2 37

PCB , SPEAKER CUP11431-1 38

PCB , SUB TRANS CUP11431-3 39

PCB , AC OUTLET CUP11431-2 40

PCB , CONNRCTOR CUP11431-4 41

PCB , MAIN CUP11395-1 42

PCB , TRANS CUP11395-2 43

PCB , PSU CUP11395-3 44

PCB , HEADPHONE CUP11551-7 45

TRANS , MAIN

TRANS , SUB

TUNER,MODULE

MOTOR

PARTS-NO Q,ty KKM1A105XC37 KKM2A062C37

KGK1A063YA KGK1A064XA KGK2A064WA CGU1A244A8 CGL1A188 CBT1A745M7K10213 CBT1A756M7K102 CGU1A245A10 CGW1A299 CDD1A013

CMY1A115 1

CUA1A190CHASSIS , BOTTOM CKL1A060 CHG1A171

CHE170

C:CKF1A212WK1

C:CJA2B043Z

KHR1A028 CKC1B082S35 1 CMH1A119SUPPORT, H/S 12

CUP11551-1PCB , U-COM 1

CUP11551-4 CUP11551-5 CUP11551-6

C:CLT5V026YE

C:CLT5L052ZE

C:HNVTFCE1E319A

BDMMDN4RB4MRC

1 2

1 1 3 1

1.2

1 1 1 1

1 1 4 4

1 1CUP11551-2/3 1 1 1

1 1 1 1 1 1 1 1 1 1 1 1

SCREW

SPECIAL SCREW 53 54

SCREW 55

SCREW 56

SCREW 57

SCREW 58

SPECIAL SCREW 59

SCREW 60

SCREW

SCREW 63

SCREW 64

SCREW 65

SCREW

SCREW67

CTS3+8J CHD1A016 CTB3+6JSCREW CTB3+6F CTB3+10G CTWS3+10G CSN2+4 CHD1A012 CTB3+16J CTB3+8J

CTW3+16J CTW3+8J CTB4+6J CTB4+6FFZ 4 CTB3+6JFZ CTB3+10GFZ

C:14 C:19

4 4 7 7 10 1 2 15 12 8 4SCREW CTW3+14J61

5 4

X10

X21

X10

1-9 1-10

1. BLOCK DIAGRAM

2-22 2-23

BLOCK DIAGRAM

2-24 2-25

2. WIRING DIAGRAM

2-26 2-27

3. SCHEMATIC DIAGRAMS

MAIN SCHEMATIC DIAGRAMS

2-28 2-29

u-COM & GUIDE CIRCUIT DIAGRAM

2-30 2-31

INPUT SCHEMATIC DIAGRAM

2-32 2-33

+ 31 hidden pages

NAD L-76 Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual