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1. Safety Precautions
1.1. General Guide Lines
1. It is advisable to insert an isolation transformer in the AC supply
before servicing a hot chassis.
2. When servicing, observe the original lead dress, especially the
lead dress in the high voltage circuits.
If a short circuit is found, replace all parts which have been
overheated or damaged by the short circuit.
3. After servicing, see to it that all the protective devices such as
insulation barriers, insulation papers, shields, and isolation R-C
combinations, are properly installed.
4. When the receiver is not to be used for a long period of time,
unplug the power cord from the AC outlet.
5. Potential, as high as 31.5kV , is present when this monitor is in
operation. Operation of the Projection Monitor without the rear
cover involves the danger of a shock hazard from the power
supply. Servicing should not be attempted byanyone who is not
thoroughly familiar with the precautions necessary when working
on high voltage equipment. Always discharge the anode of the
projection tube to the Projection Monitor chassis before handling
the tube.
6. After servicing make the following leakage current checks to
prevent the customer from being exposed to shock hazards.
1.2. Leakage Current Cold Check
1. Unplug the AC cord and connect a jumper between the two
prongs on the plug.
2. Turn on the Projection Monitor's power switch.
3. Measure the resistance value, with an ohmmeter, between the
jumpered AC plug and each exposed metallic cabinet part on the
projection monitor, such as screw heads, connectors, control
shafts, etc. When the exposed metallic part has a returnpath to
the chassis, the reading should be between 4 M
When the exposed metal does not have a return path to the
4
and 20 M
.
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