2. Measure the resistance value, with an ohmmeter, 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 ohm and 5.2M ohm. When the
exposed metal does not have a return path to the chassis, the reading must be ∞ ∞ ∞ ∞
1.3. LEAKAGE CURRENT HOT CHECK (See
1. Plug the AC cord directly into the AC outlet. Do not use an isolation transformer for
2. Connect a 1.5K ohm, 10 watts resistor, in parallel with a 0.15 micro farad capacitor,
between each exposed metallic part on the set and a good earth ground such as a
water pipe, as shown in
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.
2. PREVENTION OF ELECTRO STATIC DISCHARGE
(ESD) TO ELECTROSTATICALLY SENSITIVE(ES)