1-2 Servicing Precautions
WARNING: First read
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
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 Electrostatic Sensitive Devices (ESDs)
1. Some semiconductor (solid state) devices are easily damaged by static electricity. Such components are called Electrostatic 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
4.Do not use
5.Use only a
6.Use only an
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.