2. Connect a1.5k , 10 watts resistor, inparallel with a0.15 F
capacitors, between each exposed metallicpart on the set and a
good earth ground such as awater pipe, as showninFigure 1.
3. Use an AC voltmeter, with 1000 ohms/voltor more sensitivity, to
measure the potential across the resistor.
4. Check each exposed metallicpart, and measure the voltage at
each point.
5. Reverse the AC plug inthe AC outlet and repeat each of the above
measurements.
6. The potential at anypoint shouldnot exceed 0.75 volts RMS. A
leakage current tester (Simpson Model 229 or equivalent) maybe
used to make the hot checks, leakage current must not exceed 1/2
milliamp. Incase ameasurement isoutside of the limits specified,
there isapossibilityof ashock hazard, and the equipment should
be repaired and rechecked before itisreturned to the customer.
2. PREVENTION OF ELECTRO STATIC DISCHARGE
(ESD) TO ELECTROSTATICALLY SENSITIVE (ES)
DEVICES
Some semiconductor(solidstate) devices canbe damagedeasilybystatic electricity. Such
components commonlyare calledElectrostaticallySensitive (ES) Devices. Examples of typical
ES devices are integratedcircuits and some field-effect transistors and semiconductor"chip"
components. The following techniques shouldbe usedtohelpreduce the incidence of
component damage causedbyelectrostatic discharge (ESD).
1. Immediatelybefore handling anysemiconductor component or
semiconductor-equipped assembly, drainoff anyESDon your
bodybytouching aknownearth ground. Alternatively, obtainand
wear acommerciallyavailabledischarging ESDwrist strap, which
shouldbe removed for potential shock reasons prior to applying
power to the unitunder test.
2. After removing an electrical assemblyequipped with ES devices,
place the assemblyon aconductive surface such as alminum foil,
to prevent electrostaticcharge buildup or exposure of the
assembly.
3. Use onlyagrounded-tipsoldering iron to solder or unsolder ES
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