Safety Notice; Safety Precaution; Leakage Current Cold Check - Panasonic BT-H1350Y Service Manual

BT-H1350Y
e PRODUCT COMPLIES WITH DHHS RULES 21 CFR SUBCHAPTER J IN EFFECT AS OF DATE OF
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, It 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
sion of PANASONIC COMMUNICATIONS & SYSTEMS COMPANY.
Safety Precaution LEAKAGE CURRENT COLD CHECK
GENERAL GUIDELINES 1. Unplug the AC cord and connect a jumper between the
| а E - two prongs on the plug.
1. It is advisable to insert an isolation transformer in the КР ~ > г
ёх Е 2. Turn on the monitor's power switch.
AC supply before servicing a hot chassis. . |
6,5 არე : 3. Measure the resistance value, with an ohmmeter,
2. When servicing, observe the original lead dress, especially у
n ; — between the jumpered AC plug and each exposed
the lead dress in the high voltage circuits. If a short . г გ
ў " . н а ш а " 6 metallic cabinet part on the monitor, such as screwheads,
circuit is found, replace all parts which have been
" c connectors, control shafts, etc.
overheated or damaged by the short circuit.
vi Е à | When the exposed metallic part has a return path to the
3. After servicing, see to it that all the protective devices Р P წ
а с а у у s chassis, the reading should be more than 1MQ.
such as insulation barriers, insulation papers, shields, and
isolation R-C combinations, are properly installed.
4. Before turning the monitor on, measure the resistance
When the exposed metal does not have a return path to
the chassis, the reading must be oo.
between B+ line and cold side chassis ground. Connect LEAKAGE CURRENT HOT CHECK (See Fig. 1)
the © side of an ohmmeter to the B+ lines, and the ® 1. Plug the AC cord directly into the AC outlet. Do not
side to chassis ground. Each line should have more use an isolation transformer for this check.
resistance than specified, as follows: 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.
103V (1C804 ©)
20% (1С751 ®©)
18.5V (TPA85)
15V (1C802 Q)
12V (1C802 9)
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
5. When the monitor is not used for a long period of eguivalent) may be used to make the hot checks, leakage
time, unplug the power cord from the AC outlet. current must not exceed 500uA. In case a measurement
6. Potentials, as high as 24.0kV+1kV are present when is outside of the limits specified, there is a possibility
this monitor is in operation. Operation of the monitor of a shock hazard, and the monitor should be repaired
without the rear cover involves. the danger of a shock and rechecked before it is returned to the customer.
hazard from the monitor power supply. Servicing
should not be attempted by anyone who is not Hot-Check Circuit
thoroughly familiar with the precautions necessary when AC VOLTMETER
working on high voltage equipment. Always discharge
the anode of the picture tube to chassis ground before
handiing the tube.
TO
7. After servicing, make the following leakage current INSTRUMENT'S COLD
і EXPOSED WATER PIPE
checks to prevent the customer from being exposed to METAL PARTS 1.5k 2. ТОМ j J (GROUND)
shock hazards.
Fig. 1