Safety Precautions; General Guidelines - Panasonic TH-37LRT12U Service Manual

1 Safety Precautions

1.1.

General Guidelines

1. When conducting repairs and servicing, do not attempt to modify the equipment, its parts or its materials.
2. When wiring units (with cables, flexible cables or lead wires) are supplied as repair parts and only one wire or some of the
wires have been broken or disconnected, do not attempt to repair or re-wire the units. Replace the entire wiring unit instead.
3. When conducting repairs and servicing, do not twist the Faston connectors but plug them straight in or unplug them straight
out.
4. When servicing, observe the original lead dress. If a short circuit is found, replace all parts which have been overheated or
damaged by the short circuit.
5. After servicing, see to it that all the protective devices such as insulation barriers, insulation papers shields are properly
installed.
6. After servicing, make the following leakage current checks to prevent the customer from being exposed to shock hazards.
1.1.1. Leakage Current Cold Check
1. Unplug the AC cord and connect a jumper between the
two prongs on the plug.
2. Measure the resistance value, with an ohmmeter,
between the jumpered AC plug and each exposed metal-
lic cabinet part on the equipment such as screwheads,
connectors, control shafts, etc. When the exposed metal-
lic part has a return path to the chassis, the reading
above 4Mohm.
When the exposed metal does not have a return path to
the chassis, the reading must be
= =
R C
s s
1500 0.22
R =
b
U
500
Figure 1. Leakage Current Test Tool
leakage current
TH-32/37LRT12
test tool
AC N
The GND of test ports
AC IN
.
10k
( V )
0.022 V
1
oscilloscope
U1, U2
AC POWER
SOURCE
N
fix port
L N
SW
leakage current outlet
Figure 2.
1.1.2. Leakage Current Check (See Figure
1 and Figure 2)
1. Plug the AC cord directly into the AC outlet. Do not use
an isolation transformer for this check.
2. Make a leakage current test loop as shown in Figure 1.
3. The method of connecting leakage current test loop is
shown in Figure 2.
4. The measure value of U1(V) should be less than 35Vp
and U2(V) should be less than 0.35Vp.
( V )
U
2
3
TH-32LRT12U-A * TH-37LRT12U/M/A