NAD M12 Service Manual Download

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SUBJECT: GRAPHIC SYMBOLS

PRODUCT SAFETY SERVICING GUIDELINES FOR AUDIO PRODUCTS

A.C. VOLTMETER

GOOD EARTH GROUND
SUCH AS THE WATER
PIPE. CONDUIT. ETC

PLACE THIS PROBE
ON EACH EXPOSED
METAL PART

CAUTION

: DO NOT ATTEMPT TO MODIFY THIS

PRODUCT IN ANY WAY, NEVER PERFORM CUSTOM-
IZED INSTALLATIONS WITHOUT MANUFACTURER’S
APPROVAL. UNAUTHORIZED MODIFICATIONS WILL
NOT ONLY VOID THE WARRANTY, BUT MAY LEAD TO
YOUR BEING LIABLE FOR ANY RESULTING PROP-
ERTY DAMAGE OR USER INJURY.

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

WHILE SERVICING, USE AN ISOLATION TRANS-
FORMER FOR PROTECTION FROM A.C. LINESHOCK.

SAFETY CHECKS

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

SUBJECT : FIRE & SHOCK HAZARD
1

.BE SURE THAT ALL COMPONENTS ARE POSI-

TIONED IN SUCH A WAY AS TO AVOID POSSIBILITY
OF ADJACENT COMPONENT SHORTS.THIS IS ESPE-
CIALLY IMPORTANT ON THOSE MODULES WHICH
ARE TRANSPORTED TO AND FROM THE REPAIR
SHOP.

. NEVER RELEASE A REPAIR UNLESS ALL PROTEC-

TIVE 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 POLAR-
IZED LINE PLUG HAS NOT BEEN DEFEATED.

. SOLDERING MUST BE INSPECTED TO DISCOVER

POSSIBLE COLD SOLDER JOINTS, SOLDER
SPLASHES OR SHARP SOLDER POINTS. BE CER-
TAIN TO REMOVE ALL LOOSE FOREIGN PARTICLES.

. CHECK FOR PHYSICAL EVIDENCE OF DAMAGE

OR DETERIORATION TO PARTS AND COMPONENTS.
FOR FRAYED LEADS, DAMAGED INSULATION
(INCLUDING A.C. CORD). AND REPLACE IF NECES-

. NO LEAD OR COMPONENT SHOULD TOUCH A

RECIVING TUBE OR A RESISTOR RATED AT 1 WATT
OR MORE. LEAD TENSION AROUND PROTRUNING
METAL SURFACES MUST BE AVOIDED.

. 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 UNRECOM-
MENDED CIRCUIT MODIFICATIONS.

. AFTER RE-ASSEMBLY OF THE SET ALWAYS PER-

FORM AN A.C. 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 SAFE TO
OPERATE WITHOUT DANGER OF ELECTRICAL
SHOCK. DO NOT USE A LINE ISOLATION TRANS-
FORMER DURING THIS TEST USE AN A.C. VOLTME-
TER, HAVING 5000 OHMS PER VOLT OR MORE SEN-
SITIVITY, IN THE FOLLOWING MANNER; CONNECT A
1500 OHM 10 WATT RESISTOR, PARALLELED BY A
.15 MFD. 150.V A.C TYPE CAPACITOR BETWEEN A
KNOWN GOOD EARTH GROUND (WATER PIPE,
CONDUIT,ETC.) AND THE EXPOSED METALLIC
PARTS, ONE AT A TIME. MEASURE THE A.C. VOLT-
AGE ACROSS THE COMBINATION OF 1500OHM
RESISTOR AND .15 MFD CAPACITOR. REVERSE THE
A.C. PLUG AND REPEAT A.C. VOLTAGE MEASURE-
MENTS FOR EACH EXPOSED METALLIC PART. VOLT-
AGE MEASURED MUST NOT EXCEED 75 VOLTS
R.M.S. THIS CORRESPONDS TO 0.5 MILLIAMP A.C
ANY VALUE EXCEEDING THIS LIMIT CONSTITUTES A
POTENTIAL SHOCK HAZARD AND MUST BE COR-
RECTED IMMEDIATELY.

THE LIGHTNING FLASH WITH APROWHEAD SYMBOL. WITHIN AN EQUILATERAL TRIANGLE, IS INTENDED
TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF UNINSULATED “DANGEROUS VOLTAGE”
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 SERVICE
PERSONNEL TO THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN SERVICE LITERATURE.