1.1.2. Leakage Current Hot Check
1 Safety Precautions
1.1. 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, ensure that all the protective devices such as insulation barriers, insulation papers shields are properly installed.
3. After servicing, check for leakage current checks to prevent 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. Using an ohmmeter measure the resistance value, between the jumpered AC plug and each exposed metallic cabinet part on
the equipment such as screwheads, connectors, control shafts, etc. When the exposed metallic part has a return path to the
chassis, the reading should be between 1M
Ω
and 5.2
Ω
.
When the exposed metal does not have a return path to the chassis, the reading must be
.
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. should the measurement is outside of the limits
specified, there is a possibility of a shock hazard, and the equipment should be repaired and re-checked before it is returned
to the customer.
Fig. 1
3
SA-PM4E / SA-PM4EB / SA-PM4EG
Summary of Contents for SA-PM4E
Page 4: ...1 2 Caution for AC Cord 4 SA PM4E SA PM4EB SA PM4EG ...
Page 12: ...7 3 Disc Information 12 SA PM4E SA PM4EB SA PM4EG ...
Page 28: ... Replacement of CD Servo P C B 28 SA PM4E SA PM4EB SA PM4EG ...
Page 30: ...10 2 Checking and Repairing of Transformer P C B 30 SA PM4E SA PM4EB SA PM4EG ...
Page 32: ...10 4 Checking and Repairing of Panel and HP Music Port P C B 32 SA PM4E SA PM4EB SA PM4EG ...
Page 38: ...SA PM4E SA PM4EB SA PM4EG 38 ...
Page 42: ...SA PM4E SA PM4EB SA PM4EG 42 ...
Page 44: ...44 SA PM4E SA PM4EB SA PM4EG ...
Page 56: ...SA PM4E SA PM4EB SA PM4EG 56 ...