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| CT-S1390Y
MANUFACTURE.
IMPORTANT
SAFETY
NOTICE
There are special components
used in Panasonic Monitor sets which are important for safety.
These parts are
shaded on the schematic diagram.
|t is essential that these critical parts should be replaced with manufacturer's
specified
parts to prevent
X-RADIATION,
shock, fire, or other hazards.
Do not modify the original design
without permission of PANASONIC
BROADCAST
& TELEVISION
SYSTEMS
COMPANY.
Safety Precaution
GENERAL GUIDELINES
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. Before turning the monitor on, measure
the resistance
between 130V line and hot side ground (TP92), between
B+ line and cold side ground (TPA5).
Connect the O
side of an ohmmeter to the B+ lines, and the @ side to
ground (ТРА5).
Each line should have more resistance
than specified, as follows:
150У (ТР9Г
11.1V (TPA6)
5000
17.3V (TPA7)
24.5V (TPA8)
186V (TPA10)
5000
100kQ
5. When the monitor is not used for a long period of time,
unplug the power cord from the AC outlet.
6. Potentials, as high as 24.5kV+1.5kV
are present when
this monitor is in operation.
Operation of the monitor
without
the rear cover involves. the danger of a shock
hazard
from
the
monitor
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 chassis ground before
handling the tube.
7. After
servicing,
make
the
following
leakage
current
checks to prevent the customer from being exposed to
shock hazards.
LEAKAGE
CURRENT
COLD
CHECK
1. Unplug the AC cord and connect a jumper between the
two prongs on the plug.
2. Turn on the 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 monitor, such as screwheads,
connectors, control shafts, etc.
When the exposed metallic part has a return path to the
chassis, the reading should be more than 1MQ.
When the exposed metal does not have a return path to
the chassis, the reading must be oo.
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 1.5 kQ, 10 watt resistor, in parallel with a
0.15 uF capacitor, between
each exposed metallic part
on the set and a good earth ground such as a water pipe,
as shown in
Fig. 1.
3. Use a high impedance AC voltage meter to measure the
potential across the resistor.
4. Check
each
exposed
metallic
part,
and
measure
the
voltage at each point.
5. The potential at any point should not exceed 0.75 volts
RMS.
A leakage current tester (Simpson Model 229 or
equivalent) may be used to make the hot checks, leakage
current must not exceed 500uA.
In case a measurement
is outside of the limits specified, there is a possibility
of a shock hazard, and the monitor should be repaired
and rechecked before it is returned to the customer.
Hot-Check Circuit
AC VOLTMETER
TO
INSTRUMENT'S
COLD
EXPOSED
WATER PIPE
METAL PARTS
J (GROUND)
1.5k2, 10W
Fig. 1
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