CAUTION: To prevent damage to the computer when you are removing or installing internal components, observe these precautions:

Keep components in their electrostatic-safe containers until you are ready to install them.

Before touching an electronic component, discharge static electricity by using the guidelines described in this section.

Avoid touching pins, leads, and circuitry. Handle electronic components as little as possible. If you remove a component, place it in an electrostatic-safe container.

The following table shows how humidity affects the electrostatic voltage levels generated by different activities.

CAUTION: A product can be degraded by as little as 700 V.

Typical electrostatic voltage levels

 

 

Relative humidity

 

 

 

 

 

Event

10%

40%

55%

 

 

 

 

Walking across carpet

35,000 V

15,000 V

7,500 V

 

 

 

 

Walking across vinyl floor

12,000 V

5,000 V

3,000 V

 

 

 

 

Motions of bench worker

6,000 V

800 V

400 V

 

 

 

 

Removing DIPS from plastic tube

2,000 V

700 V

400 V

 

 

 

 

Removing DIPS from vinyl tray

11,500 V

4,000 V

2,000 V

 

 

 

 

Removing DIPS from Styrofoam

14,500 V

5,000 V

3,500 V

 

 

 

 

Removing bubble pack from PCB

26,500 V

20,000 V

7,000 V

 

 

 

 

Packing PCBs in foam-lined box

21,000 V

11,000 V

5,000 V

 

 

 

 

34

Chapter 4 Removal and replacement procedures