Sanyo DP32640 Service Manual

Sanyo DP32640 Service Manual Manual pdf 2 page image

– 2 –SAFETY PRECAUTIONSWARNING: The chassis of this receiver has a floatingground with the potential of one half the AC line voltage inrespect to earth ground. Service should not be attempted byanyone not familiar with the precautions necessary whenworking on this type of equipment.The following precautions must be observed:1. An isolation transformer must be connected in the powerline between the receiver and the AC line before any ser-vice is performed on the receiver.2. Comply with all caution and safety-related notes provid-ed inside the cabinet, on the chassis, and on the back.3. When replacing a chassis in the cabinet, always be certainthat all the protective devices are installed properly, suchas control knobs, adjustment covers, shields and barriers.4. Before replacing the back cover of the set, thoroughlyinspect the inside of the cabinet to see that no stray partsor tools have been left inside.Before returning any television to the customer, theservice technician must perform the following safetychecks to be sure that the unit is completely safe tooperate without danger of electrical shock.ANTENNA COLD CHECKRemove AC plug from the 120 VAC outlet and place ajumper across the two blades. Connect one lead of an ohm-meter to the jumpered AC plug, and touch the other lead toeach exposed antenna terminal (UHF and VHF antenna ter-minals). The resistance must measure between 1M ohm and5.2M ohm. Any resistance value below or above this rangeindicates an abnormality which requires corrective action.LEAKAGE CURRENT CHECKPlug the AC line cord directly into a 120 VAC outlet. (Do notuse an isolation transformer for this check.) Use an AC volt-meter, that has 5000 ohms per volt or more sensitivity.Connect a 1500 ohm 10 watt resistor, paralleled by a 0.15 μF150 VAC capacitor, between a known good earth ground(water pipe, conduit, etc.) and all exposed metal parts of thecabinet (antennas, handle bracket, metal cabinet, screwheads, metal overlays, control shafts, etc.). Measure the ACvoltage across the 1500 ohm resistor. The AC voltageshould not exceed 750 mV. A reading exceeding 750 mVindicates that a dangerous potential exists. The fault mustbe located and corrected. Repeat the above test with thereceiver power plug reversed.NEVER RETURN A RECEIVER TO THE CUSTOMERWITHOUT TAKING THE NECESSARY CORRECTIVE ACTION.PRODUCT SAFETY NOTICEWhen replacing components in a receiver, always keep inmind the necessary product safety precautions. Pay specialattention to the replacement of components marked with ain the parts list and in the schematic diagrams. To ensuresafe product operation, it is necessary to replace those com-ponents with the exact same PARTS.SERVICING ELECTROSTATICALLY SENSITIVE DEVICESSemiconductors (solid-state devices) that can be damagedby static electricity are referred to as ElectrostaticallySensitive (ES) devices. Examples of typical ES devices are:Integrated Circuits (IC), Field-Effect Transistors (FET), and“chip” components. The following techniques should beobserved strictly, to reduce the occurrence of semiconduc-tor damage due to electrostatic discharge.1. Immediately prior to handling any semiconductor com-ponent or an assembly containing a semiconductordevice or devices, discharge the electrostatic buildup onyour body by touching a known earth ground. You mayalso obtain and wear a commercially available discharg-ing wrist strap device.CAUTION: Be sure to remove the wrist strap beforeapplying power to any unit being serviced.2. After removing an ES equipped assembly, place it on aconductive surface, such as, aluminum foil, to preventbuildup or exposure to static electricity.3. Use only grounded-tip soldering irons to solder or unsol-der ES devices.4. Use only anti-static solder removal devices. Some suc-tion-type devices can generate static electricity adequateto damage ES devices.5. A replacement ES device will come packaged in protectivematerial (conductive foam, aluminum foil, or some compa-rable conductive material). Do Not remove an ES devicefrom its protective packaging unless you are prepared toinstall it immediately.6. Precisely prior to removing an ES device from its protectivepackaging, touch the protective packaging to the chassis orassembly in which the device will be installed.CAUTION: Be sure that no power is applied to the chassisor circuit assembly.7. Incidental body movements, such as, lifting a foot froma carpeted floor or the rubbing of fabric together cangenerate static electricity sufficient to damage ES devices.Therefore, minimize all body movements while handlingexposed (unpackaged) ES devices.SAFETY INSTRUCTIONS