Panasonic DMR-E50EB, Service Manual

Page: 5 / 196

Figure 1
1.1.2. 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 , 10 watts resistor, in parallel with a 0.15 F 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 mu3st not exceed 1/2 milliamp. In case a measurement is outsideof
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.
2. PREVENTION OF ELECTRO STATIC DISCHARGE
(ESD) TO ELECTROSTATICALLY SENSITIVE (ES)
DEVICES
Some semiconductor (solid state) devices can be damaged easily by static electricity.
Such components commonly are called Electrostatically Sensitive (ES) Devices.
Examples of typical ES devices are integrated circuits and some field-effect