SANYO 20930-00 CHASSIS
Service Manual

SAFETY INSTRUCTIONS
SAFETY PRECAUTIONS
WARNING: The chassis of this receiver has a floating ground with the potential of one half the AC line voltage in respect to earth ground. Service should not be attempted by anyone not familiar with the precautions necessary when working on this type of equipment. The following precautions must be observed: 1. An isolation transformer must be connected in the power line between the receiver and the AC line before any service is performed on the receiver. 2. Comply with all caution and safety-related notes provided on the side of the cabinet, inside the cabinet, on the chassis, and the picture tube. 3. When replacing a chassis in the cabinet, always be certain that all the protective devices are installed properly, such as control knobs, adjustment covers, shields and barriers. DO NOT OPERATE THIS TELEVISION RECEIVER WITHOUT THE PROTECTIVE SHIELD IN POSITION AND PROPERLY SECURED. 4. Before replacing the back cover of the set, thoroughly inspect the inside of the cabinet to see that no stray parts or tools have been left inside. Before returning any television to the customer, the service technician must perform the following safety checks to be sure that the unit is completely safe to operate without danger of electrical shock.
AC OUTLET To be touched to all of exposed metal parts. 2000 ohm 10 watt READING SHOULD NOT EXCEED 1400 mV. AC VOLTMETER (5000 ohms per volt or more sensitivity)

TELEVISION RECEIVER

Good earth ground such as a water pipe, conduit, etc.

Voltmeter Hook-up for Leakage Current Check.

X-RADIATION PRECAUTION
The primary source of X-RADIATION in solid-state receivers is the picture tube. The picture tube is specially constructed to limit X-Ray emission. For continued X-RADIATION protection, the replacement tube must be the same type as the original (including the suffix letter in the part numbers). Excessive high voltage may produce potentially hazardous X-RADIATION. To avoid such hazards, the high voltage must be maintained within specific limits. Refer to the XRADIATION WARNING NOTE on the CHASSIS SCHEMATIC in this service manual for specific high voltage limits. If the high voltage exceeds specified limits, check the components specified on the chassis schematic diagram and take the necessary corrective action. Carefully follow the instructions for the +B Voltage Check and the High Voltage Check to maintain the high voltage within the specified limits.

ANTENNA COLD CHECK
Remove AC plug from the 220 VAC outlet and place a jumper across the two blades. Connect one lead of an ohmmeter to the jumpered AC plug, and touch the other lead to each exposed antenna terminal (UHF and VHF antenna terminals). The resistance must measure 10M ohm or over. Any resistance value below this range indicates an abnormality which requires corrective action.

LEAKAGE CURRENT CHECK
Plug the AC line cord directly into a 220 VAC outlet. (Do not use an isolation transformer for this check.) Use an AC voltmeter, that has 5000 ohms per volt or more sensitivity. Connect a 2000 ohm 10 watt resistor, between a known good earth ground (water pipe, conduit, etc.) and all exposed metal parts of the cabinet (antennas, earphone jack, screwheads, metal overlays, control shafts, etc.). Measure the AC voltage across the 2000 ohm resistor. The AC voltage should not exceed 1400 mV. A reading exceeding 1400 mV indicates that a dangerous potential exists. The fault must be located and corrected. Repeat the above test with the receiver power plug reversed. NEVER RETURN A RECEIVER TO THE CUSTOMER WITHOUT TAKING THE NECESSARY CORRECTIVE ACTION.

PRODUCT SAFETY NOTICE
When replacing components in a receiver, always keep in mind the necessary product safety precautions. Pay special attention to the replacement of components marked with a star (5) in the parts list and in the schematic diagrams. To ensure safe product operation, it is necessary to replace those components with the exact same PARTS.

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