Sam4s ER-5115 Servicing Precautions, Precautions for Electrostatically Sensitive Devices ESDs

1-2 Servicing Precautions

WARNING: First read the-Safety Precautions-section of this manual. If some unforeseen circumstance creates a conflict between the servicing and safety precautions, always follow the safety precautions.

WARNING: An electrolytic capacitor installed with the wrong polarity might explode.

1.Servicing precautions are printed on the cabinet. Follow them.

2.Always unplug the units AC power cord from the

AC power source before attempting to:

(a)Remove or reinstall any component or assembly

(b)Disconnect an electrical plug or connector

(c)Connect a test component in parallel with an electrolytic capacitor

3.Some components are raised above the printed circuit board for safety. An insulation tube or tape is sometimes used. The internal wiring is sometimes clamped to prevent contact with thermally hot components. Reinstall all such elements to their original position.

4.After servicing, always check that the screws, components and wiring have been correctly reinstalled. Make sure that the portion around the serviced part has not been damaged.

5.Check the insulation between the blades of the AC plug and accessible conductive parts (examples : metal panels and input terminals).

6.Insulation Checking Procedure:

Disconnect the power cord from the AC source and turn the power switch ON. Connect an insulation resistance meter (500V) to the blades of AC plug.

The insulation resistance between each blade of the AC plug and accessible conductive parts (see above) should be greater than 1 megohm.

7.Never defeat any of the B+ voltage interlocks. Do not apply AC power to the unit (or any of its assemblies) unless all solid-state heat sinks are correctly installed.

8.Always connect an instrument’s ground lead to the instrument chassis ground before connecting the positive lead ; always remove the instrument’s ground lead last.

1-3 Precautions for Electrostatically Sensitive Devices (ESDs)

1.Some semiconductor (solid state) devices are easily damaged by static electricity. Such components are called Electrostatically Sensitive Devices (ESDs); examples include: integrated circuits and some field- effect transistors. The following techniques will reduce the occurrence of component damage caused by static electricity.

2.Immediately before handling any semiconductor components or assemblies, drain the electrostatic charge from your body by touching a known earth ground. Alternatively, wear a discharging wrist- strap device. (Be sure to remove it prior to applying power - this is an electric shock precaution.)

3.After removing an ESD-equipped assembly, place it on a conductive surface such as aluminum foil to prevent accumulation of electrostatic charge.

4.Do not use freon-propelled chemicals. These can generate electrical charges that damage ESDs.

5.Use only a grounded-tip soldering iron when soldering or unsoldering ESDs.

6.Use only an anti-static solder removal device. Many solder removal devices are not rated as anti-static; these can accumulate sufficient electrical charge to damage ESDs.

7.Do not remove a replacement ESD from its protective package until you are ready to install it. Most replacement ESDs are packaged with leads that are electrically shorted together by conductive foam, aluminum foil or other conductive materials.

8.Immediately before removing the protective material from the leads of a replacement ESD, touch the protective material to the chassis or circuit assembly into which the device will be installed.

9.Minimize body motions when handling unpackaged replacement ESDs. Motions such as brushing clothes together, or lifting a foot from a carpeted floor can generate enough static electricity to damage an ESD.