HITACHI 42HDT20
Service Manual

PT2-E/G AVC1-U

SAFETY PRECAUTIONS
NOTICE: Comply with all cautions and safety-related notes located on or inside the cover case and on the chassis or plasma module. WARNING: Since the chassis of the AVC unit and Plasma Panel unit is connected to both sides of the AC power supply during operation, whenever the receiver is plugged in, service should not be attempted by anyone unfamiliar with the precautions necessary when working on this type of receiver. 1. When service is required, an isolation transformer should be inserted between power line and the receiver before any service is performed on a �HOT� chassis receiver. 2. When replacing a chassis in the receiver, all the protective devices must be put back in place, such as barriers, nonmetallic knobs, insulating cover-shields, and isolation resistors, capacitors, etc. 3. When service is required, observe the original lead dress. 4. Always use manufacturer�s replacement components. Critical components as indicated on the circuit diagram should not be replaced by another manufacturer�s. Furthermore, where a short circuit has occurred, replace those components that indicate evidence of over heating. 5. Before returning a serviced receiver to the customer, the service technician must thoroughly test the unit to be certain that it is completely safe to operate without danger of electrical shock, and be sure that no protective device built into the receiver by the manufacturer has become defective, or inadvertently defeated during servicing. Therefore, the following checks should be performed for the continued protection of the customer and service technician. Leakage Current Cold Check With the AC plug removed from the 120V AC 60Hz source, place a jumper across Line 1 and Line 2 of the three plug prongs, do not connect with the third prong, which is physical ground. Using an insulation tester (DC500V), connect one of its leads to the AC plug jumper and touch with the other lead each exposed metal part (antennas, screwheads, metal overlays, control shafts, etc.), particularly any exposed metal part having a return path to the chassis shoud have a minimum resistor reading of 4M� and a maximum resistor reading of 7.14M�. Any resistance value below or above this range indicates an abnormality which requires corrective action. An exposed metal part not having a return path to the chassis will indicate an open circuit.
DEVICE UNDER TEST

Leakage Current Hot Check This check must be done considering the AVC or the PDP monitor as one instrument each. With any of the instruments completely reassembled (being the instrument either the AVC center or the PDP monitor), plug the AC line cord directly into a 120V AC outlet. (Do not use an isolation transformer during this test.) Use a leakage current tester or a metering system that complies with the American National Standards Institute (ANSI) C101.0 Leakage Current for Appliances. In the case of the PDP monitor set the AC switch first in the ON position and then in the OFF position, measure from a known earth ground (metal waterpipe, conduit, etc.) to all exposed metal parts of the instrument (antennas, handle bracket, metal cabinet, screw heads, metallic overlays, control shafts, etc.), especially any exposed metal parts that offer an electrical return path to the chassis. Any current measured must not exceed 0.5 milliamps. Reverse the instrument power cord plug in the outlet and repeat test.

(READING LEAKAGE SHOULD NOT BE ABOVE 0.5mA) CURRENT TESTER TEST ALL EXPOSED METAL SURFACES EARTH GROUND

3-WIRE CORD ALSO TEST WITH PLUG REVERSED (USING AC ADAPTER PLUS AS REQUIRED)

AC LEAKAGE TEST ANY MEASUREMENTS NOT WITHIN THE LIMITS OUTLINED ABOVE ARE INDICATIVE OF A POTENTIAL SHOCK HAZARD AND MUST BE CORRECTED BEFORE RETURNING THE RECEIVER TO THE CUSTOMER.

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