Panasonic TX-43P950M, Руководство по обслуживанию

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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 30.0kV , 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 by anyone
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 return path to the chassis, the reading should be
between 4 M
Ω
and 20 M
Ω
.
When the exposed metal does not have a return path to the
chassis, the reading must be
.
1.3. Leakage Current Hot Check
(See Fig.1)
1. Plug the AC cord directly into the AC outlet. Do not use an
isolation transformer for this check.
2. Connect a 2k
Ω
, 10W resistor, in series with an exposed
metallic part on the projection monitor and an earth such as
a water pipe.
3. Use an AC voltmeter, with high impedance type, to
measure the potential across the resistor.
4. Check each exposed metallic part, and measure the
voltage at each point.
5. Reverse the AC plug in the AC outlet and repeat each of the
above measurements.
6. The potential at any point should not exceed 1.0V rms. In
case a measurement is outside of the limits specified, there
is a possibility of a shock hazard, and the projection monitor
should be repaired and rechecked before it is returned to
the customer.
Fig. 1
1.4. X-Radiation
Warning :
1. The potential sources of X-Radiation in projection
monitor are the High Voltage section and the projection
tube.
2. When using a projection tube test jig for service, ensure
that jig is capable of handling 31.5kV without causing X-
Radiation.
Note:
It is important use an accurate periodically calibrated high
voltage meter.
1. Set the brightness to minimum.
2. Set the service switch to the service position.
3. Measure the High Voltage. The meter reading should
indicate 31.5(+1.0,-1.5kV) . If the meter indication is out of
tolerance, immediate service and correction is required to
prevent the possibility of premature component failure.
4. To prevent an X-Radiation possibility, it is essential to use
the specified projection tube.
1 Safety Precautions
5
TX-51P950M / TX-51P950X / TX-43P950M / TX-43P950X