Sylvania 6842PF M, Руководство по обслуживанию

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2-1-1 L0655SC
SAFETY PRECAUTIONS
General Guidelines
1. 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.
2. After servicing, see to it that all the protective devices such as insulation barriers, insulation papers shields are
properly installed.
3. 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. Measure the resistance value, with an ohmmeter,
between the jumpered AC plug and each exposed
metallic cabinet part on the equipment 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 1M
Ω
and
5.2M
Ω
.
When the exposed metal does not have a return
path to the chassis, the reading must be
∞
.
Leakage Current Hot Check (See Figure 1.)
1. Plug the AC cord directly into the AC outlet. Do not
use an isolation transformer for this check.
2. Connect a 1.5k
Ω
, 10 watts resistor, in parallel with a
0.15µF capacitors, between each exposed metallic
part on the set and a good earth ground such as a
water pipe, as shown in Figure 1.
3. Use an AC voltmeter, with 1000 ohms/volt or more
sensitivity, 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 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 1/2
milliamp. In case a measurement is outside of the
limits specified, there is a possibility of a shock
hazard, and the equipment should be repaired and
rechecked before it is returned to the customer.
Hot-Check Circuit
AC VOLTMETER
TO
APPLIANCES
EXPOSED
METAL PARTS
COLD
WATER PIPE
(EARTH GROUND)
1500 10W
0.15 F
Figure1