Daewoo DTH-21S8, Service Manual

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SAFETY PRECAUTIONS
CAUTION : DO NOT ATTEMPT TO MODIFY THIS PRODUCT IN ANY WAY.
NEVER PERFORM CUSTOMIZED INSTALLATIONS WITHOUT MANUFAC-
TURER'S APPROVAL. UNAUTHORIZED MODIFICATIONS WILL NOT ONLY VOID
THE WARRANTY, BUT MAY LEAD TO YOUR BEING LIABLE FOR ANT RESULT-
ING PROPERTY DAMAGE OR USER INJURY.
SERVICE WORK SHOULD BE PERFORMED ONLY AFTER YOU ARE THOR-
OUGHLY 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 A.C. 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 TRANS-
PORTED 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 SOL-
DER JOINTS, SOLDER SPLASHES OF SHARP SOLDER POINTS. BE CER-
TAIN 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 A.C. CORD), AND REPLACE IF NECESSARY. FOLLOW ORIGI-
NAL 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 PRO-
TRUDING METAL SURFACES MUST BE AVOIDED.
6. ALL CRITICAL COMPONENTS SUCH AS FUSES, FLAMEPROOF RESISTOR,
CAPACITORS, ETC. MUST BE REPLACED WITH EXACT FACTORY TYPES.
DO NOT USE REPLACEMENT COMPONENTS OTHER THAN THOSE SPECI-
FIED OR MAKE UNRECOMMENDED CIRCUIT MODIFICATIONS.
7. AFTER RE-ASSEMBLY OF THE STE ALWAYS PERFORM AN A.C. LEAKAGE
TEST ON ALL EXPOSED METALLIC PARTS OF THE CABINET. (THE CHAN-
NEL SELECTOR KNOB, ANTENNA TERMINALS, HANDLE AND SCREWS) TO
BE SURE THE SET IS SAFE TO OPERATE WITHOUT DANGER OF ELECTRI-
CAL SHOCK. DO NOT USE A LINE ISOLATION TRANSFORMER DURING THIS
TEST USE AN A.C. 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 A.C. TYPE CAPACI-
TOR BETWEEN A KNOWN GOOD EARTH GROUND (WATER POPE, CON-
DUIT, ETC.) AND THE EXPOSED METALLIC PARTS, ONE AT A TIME.
MEASURE THE A.C. VOLTAGE ACROSS THE COMBINATION OF 1500 OHM
RESISTOR AND .15 MFD CAPACITOR. REVERSE THE A.C. PLUG AND
REPEAT A.C. VOLTAGE MEASUREMENTS FOR EACH EXPOSED METALLIC
PART. VOLTAGE MEASURED MUST NOT EXCEED .75 VOLTS R.M.S THIS
CORRESPONDS TO 0.5 MILLIAMP A.C. NAY VALUE EXCEEDING THIS LIMIT
CONSTITUTES A POTENTIAL SHOCK HAZARD AND MUST BE CORRECTED
IMMEDIATELY.
SUBJECT : X-RADIATION
1. BE SURE PROCEDURES AND INSTRUCTIONS TO ALL SERVICE PERSON-
NEL COVER THE SUBJECT OF X-RADIATION. THE ONLY POTENTIAL
SOURCE OF X-RAYS IN CURRENT T.V. RECEIVERS IS THE PICTURE TUBE.
HOWEVER, THIS TUBE DOES NOT EMIT X-RAYS WHEN THE HIGH VOLT-
AGE IS AT THE FACTORY SPECIFIED LEVEL. THE PROPER VALUE IS GIVEN
IN THE APPLICABLE SCHEMATIC. OPERATION AT HIGHER VOLT-AGES MAY
CAUSE A FAILURE OF THE PICTURE TUBE OR HIGH VOLTAGE SUPPLY
AND UNDER CERTAIN CIRCUMSTANCES, AMY PRODUCE RADIA-TION IN
EXCESS OF DESIRABLE LEVELS.
2. ONLY FACTORY SPECIFIED C.R.T ANODE CONNECTORS MUST BE
USED.DEGAUSSING SHIELDS ALSO SERVE AS X-RAY SHIELD IN COLOR
SETS. ALWAYS RE-INSTALL THEM.
3. IT IS ESSENTIAL THAT SERVICE PERSONNEL HAVE AVAILABLE AN ACCU-
RATE AND RELIABLE HIGH VOLTAGE METER. THE CALIBRATION OF THE
METER SHOULD BE CHECKED PERIODICALLY AGAINST A REFERENCE
STANDARD. SUCH AS THE ONE AVAILABLE AT YOUR DISTRIBUTOR.
4. WHEN THE HIGH VOLTAGE CIRCUITRY IS OPERATING PROPERLY THERE
IS NO POSSIBILITY OF AN X-RADIATION PROBLEM. EVERY TIME A COLOR
CHASSIS IS SERVICED, THE BRIGHTNESS SHOULD BE RUN UP AND DOWN
WHILE MONITORING THE HIGH VOLTAGE WITH A METER TO BE CERTAIN
THAT THE HIGH VOLTAGE DOES NOT EXCEED THE SPECIFIED VALUE AND
THAT IT IS REGULATING CORRECTLY. WE SUGGEST THAT YOU AND YOUR
SERVICE ORGANIZATION REVIEW TEST PROCEDURES SO THAT VOLTAGE
REGULATION IS ALWAYS CHECKED AS A STANDARD SERVICING
PROCEDURE, AND THAT THE HIGH VOLTAGE READING BE RECORDED ON
EACH CUSTOMER’S INVOICE.
5. WHEN TROUBLESHOOTING AND MAKING TEST MEASUREMENTS IN A
PRODUCT WITH A PROBLEM OF EXCESSIVE HIGH VOLTAGE, AVOID BEING
UNNECESSARILY CLOSE TO THE PICTURE TUBE AND THE HIGH VOLTAGE
SUPPLY. DO NOT OPERATE THE PRODUCT LONGER THAN IS NECESSARY
TO LOCATE THE CAUSE OF EXCESSIVE VOLTAGE.
6. REFER TO HV, B+ AND SHUTDOWN ADJUSTMENT PROCEDURES
DESCRIBED IN THE APPROPRIATE SCHEMATIC AND DIAGRAMS (WHERE
USED).
SUBJECT : IMPLOSION
1. ALL DIRECT VIEWED PICTURE TUBES ARE EQUIPPED WITH AN INTEGRA
IMPLOSION PROTECTION SYSTEM. BUT CARE SHOULD BE TAKEN TO
AVOID DAMAGE DURING INSTALLATION. AVOID SCRATCHING THE TUBE.
OF SCRATCHED REPLACE IT.
2. USE ONLY RECOMMENDED FACTORY REPLACEMENT TUBES.
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 VENTILA-
TION.
4. WALL AND SHELF MOUNTED INSTALLATIONS USING A COMMERCIAL
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 SPAC-
ERS)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 MOUNT-
ING TO THE CART. CAUTION THE CUSTOMER ON THE HAZARDS OF TRY-
ING 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 SERVICE PERSONNEL TO THE PRES-ENCE
OF UNINSULATED “DANGEROUS VOLTAGE”
THAT MAY BE OF SUFFICIENT MAGNITUDE TO CON-
STITUTE 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 ON SERVICE LITERATURE.
SUBJECT : GRAPHIC SYMBOLS
10WATT
GOOD EARTH GROUND
SUCH AS THE WATER
PIPE, CONDUIT, ETC.
1500 OHM
A.C. VOLTMETER
PLACE THIS PROBE
ON EACH EXPOSED
METAL PART
0.15 uF