-900
x
X X Ser-ies
-1200X X XSer-ies
------SAFETY PRECAUTIONS------
1-1 CAUTION:
No modification of any circuit should be attempted.
Service work should only be performed after you are
thoroughly familiar with all of the following safety
checks and servicing gu ide lines.
1-2 SAFETY CHECK
Care should be taken while servicing this CRT display
because of the high voltage used in the deflection cir
cuits. These voltages are exposed in such areas as the
associated flyback and yoke circuits.
1-3 FIRE & SHOCK HAZARD
1-3-1 Insert an isolation transformer between the CRT
display and AC power line before servicing chassis.
1-3-2 1 n servicing pay attention to original lead dress
especially in the high voltage circuit. lf a short cir
cuit is found, replace all parts which have been
overheated.
1-3-3 All the protective devices must be reinstalled per
original design.
1-3-4 Soldering must be inspected possible for cold solder
joints, frayed leads, damaged insulation, solder
splashes or sharp solder points. Be certain to remove
all foreign material.
1-4 LEAKAGE CURRENT COLD CHECK (AC
power supply model only)
1-4-1 Unplug the AC cord and connect a jumper between
the two prongs on the plug.
1-4-2 Turn the CRT display power switch on.
1-4-3 Measure the resistance value with an ohmmeter
between the jumpered AC plug and each exposed
metallic part on the CRT display such as metal
frame, screwhead, control shafts, etc.
When the exposed metallic part has a return path
to the chassis, the reading should be 1.8 megohm
minimum.
1-5 LEAKAGE CURRENT HOT CHECK (AC
power supply model only)
1-5-1 Plug the AC cord directly into the AC outlet. Do
not use an isolation transformer during this check.
1-5-2 Connect a 1500 ohm, 10 watt resistor, paralleled by
a 0.15µF capacitor between each exposed metallic
part and good earth ground (as shown in F ig. 1).
1-5-3 Use an AC voltmeter with 1000 ohm/volt or more
sensitivity and measure the AC voltage across the
combination 1500 ohm resistor and 0.15µF
capacitor.
1-5-4 Move the resistor connection to each exposed metal-
1 ic part and measure the voltage.
1-5-5 Reverse the polarity of the AC plug in the AC outlet
and repeat the above measurement.
1-5-6 Voltage measured must not exceed 7 .5 volt RMS,
from any exposed metallic part to ground. A leak
age current tester may be used in the above hot
check, in which case any current measured must not
exceed 5.0 milliamp. In the case of a measurement
exceeding the 5.0 milliamp value, a rework is
required to eliminate the chance of a shock hazard.
Note: High voltage is present when this CRT display is
operating. Always discharge the anode of the
picture tube to the display monitor chassis to
prevent shock hazard.
AC VOLTMETER
(EARTH
GROUND)
To
INSTRUMl::NT'S
EXPOSED
__ _,__..__-'W',---��-i
MET AL PARTS
1500n, 10W
Fig. 1
1-6 IMP.LOSION PROTECTION
All Panasonic picture tu bes are equipped with an integral
implosion protection system, but care should be ta ken
to avoid damage and scratching during installation. Use
only Panasonic replacement picture tu bes.
1-7 X-RADIATION
WARNING: The only potential source of X-Radiation is
the picture tube. However when the high voltage circuitry
is operating properly there is no possibility of X-Radiation
problem. The basic precaution which must be exerc ised
is to keep the high voltage at the following factory
recommended level.
Note: lt is important to use an accurate periodically
calibrated high voltage meter.
1-7-1 To measure the high voltage, use a high impedance
high voltage meter.
Connect (-) to chassis and (+) to the CRT anode
button.
1-7-2 Turn the Brightness control fully counterclockwise.
1-7-3 Measure the high voltagg. The high voltage rneter
should indicate at the following factory-r€com
mended level.
1-7-4 lf the upper meter indication exceeds the maxirnum
level, immediate service is required to prevent the
possiblity of premature component fci I ure.
1-7-5 To prevent X-Radiation possibility, it is essential to
use the specified picture tube.
1-7-6 The following are the nominal and maxirnum
high voltage at zero beam current at rated voltage.
Model
Nominal
Maximum
M-900xxx
llkV
14.5kV
M-1200xxx
14kV
17.0kV
IMPORTANT SAFETY NOTICE
There are special components used in Panasonic CRT
displays which are important for safety _ These parts are
shaded on the schematic diagram and on the replac1rnent
parts list. lt is essential that these critical parts
shoil
d be
replaced with manufacture's specified parts to Prevent
X-RADIATION, shock, fire or other hazards. Do not
modify the original design without written permiss:�n of
the Panasonic company or this will void the original parts
and labor guarantee.
-1-
