Removal and replacement procedures 4–4

Equipment guidelines

Grounding equipment must include either a wrist strap or a foot strap at a grounded workstation.
■When seated, wear a wrist strap connected to a grounded system. Wrist straps are flexible straps with a
minimum of one megohm ±10% resistance in the ground cords. To provide proper ground, wear a strap snugly
against the skin at all times. On grounded mats with banana-plug connectors, use alligator clips to connect a
wrist strap.
■When standing, use foot straps and a grounded floor mat. Foot straps (heel, toe, or boot straps) can be used at
standing workstations and are compatible with most types of shoes or boots. On conductive floors or
dissipative floor mats, use foot straps on both feet with a minimum of one megohm resistance between the
operator and ground. To be effective, the conductive strips must be worn in contact with the skin.
The following grounding equipment is recommended to prevent electrostatic damage:
■Antistatic tape
■Antistatic smocks, aprons, and sleeve protectors
■Conductive bins and other assembly or soldering aids
■Nonconductive foam
■Conductive tabletop workstations with ground cords of one megohm resistance
■Static-dissipative tables or floor mats with hard ties to the ground
■Field service kits
■Static awareness labels
■Material-handling packages
■Nonconductive plastic bags, tubes, or boxes
■Metal tote boxes
■Electrostatic voltage levels and protective materials
The following table lists the shielding protection provided by antistatic bags and floor mats.

Unknown user password

If the computer you are servicing has an unknown user password, follow these steps to clear the password:
✎These steps also clear CMOS.
1. Shut down the computer. If you are unsure whether the computer is off or in Hibernation, turn the computer on,
and then shut it down through the operating system.
2. Disconnect all external devices connected to the computer.
3. Disconnect the power from the computer by first unplugging the power cord from the AC outlet and then
unplugging the AC adapter from the computer.
4. Remove the battery (see “Battery” on page 4-7).
5. Remove the real-time clock (RTC) battery (see “RTC battery” on page4-12).
6. Wait approximately 5 minutes.
Material Use Voltage protection level
Antistatic plastic Bags 1,500 V
Carbon-loaded plastic Floor mats 7,500 V
Metallized laminate Floor mats 5,000 V