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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 cord outlet.
5. Potential, as high as 27.0kV is present when this receiver is in
operation. Operation of the receiver without the rear cover
involves the danger of a shock hazard from the receiver power
supply. Servicing should not be attempted by anyone who is not
thoroughly familiar with the precautions necessary when working
on high voltage equipment. Always discharge the anode of the
picture tube to the receiver chassis before handling the tube.
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 receiver's power switch. / Measure the resistance
value, with an ohmmeter, between the jumper AC plug and each
exposed metallic cabinet part on the receiver, such as screw
heads, aerials, connectors, control shafts, etc. When the exposed
metallic part has a return path to the chassis, the reading should
be between 4 M and 20 M . When the exposed metal does not
have a return path to the chassis, the reading must be infinite.
1.3. Leakage Current Hot Check (Fig. 1)
1. Plug the AC cord directly into the AC outlet. Do not use an
isolation transformer for this check.
2. Check a 2 k non-inductive resistor and an AC/DC current meter,
in series with each exposed metallic part on the receiver in turn
and an earth such as a water pipe.
The current from any point should not exceed 0.7 mA peak AC or
2 mA DC. In the case of a measurement being outside of these
limits specified, there is a possibility of a shock hazard and the
receiver should be repaired and rechecked before it is returned to
the customer.
3
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