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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 screwheads, connectors, control shafts, 
etc. When the exposed metallic part has a return path to thechassis, 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

.

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 

 .

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 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.

 

 

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 transistorsand semiconductor "chip" components. The following techniques should be used 
to help reduce the incidence of component damage caused by electro static discharge (ESD).

1.  Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any ESD on your body by touching a known earth 

ground. Alternatively, obtain and wear a commercially available discharging ESD wrist strap, whichshould be removed for potential shock reasons prior to 
applying power to the unit under test.

2.  After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as alminum foil, to prevent electrostatic 

charge buildup or exposure of the assembly.

3.  Use only a grounded-tip soldering iron to solder or unsolder ES devices.

4.  Use only an anti-static solder removal device. Some solder removal devices not classified as "anti-static (ESD protected)" can generate electrical charge 

sufficient to damage ES devices.

5.  Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ES devices.

6.  Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most replacement ES devices are 

packaged with leads electrically shorted together by conductive foam, alminum foil or comparableconductive material).

7.  Immediately before removing the protective material from the leads of a replacement ES device, touch the protective material to the chassis or circuit assembly 

into which the device will be installed.

Caution

 

Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.

8.  Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise hamless motion such as the brushing together of your clothes fabric 

or the lifting of your foot from a carpeted floor can generate static electricity (ESD) sufficient todamage an ES device).