Changing Jumper Settings; Cmos Clear Jumper - Silicon Graphics 1450 Maintenance Manual

Changing Jumper Settings

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CMOS Clear Jumper

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Follow the instructions in this section to change the settings for the CMOS clear jumper
(JP4), the password clear jumper (JP3), and the recovery boot jumper (JP2).
Observe the following safety and ESD precautions before changing jumper settings:
Caution: ESD can damage disk drives, boards, and other parts. We recommend that you
do all procedures in this chapter only at an ESD-protected workstation. If one is not
available, provide some ESD protection by wearing an antistatic wrist strap attached to
chassis ground—any unpainted metal surface—on your system when handling parts.
Caution: Always handle boards carefully. They can be extremely sensitive to ESD. Hold
boards only by their edges. After removing a board from its protective wrapper or from
the system, place it component-side upon a grounded, static-free surface. If you place the
baseboard on a conductive surface, the battery leads may short out. If they do, this will
result in a loss of CMOS data and will drain the battery. Use a conductive foam pad if
available but not the board wrapper. Do not slide the board over any surface.
Caution: A jumper is a small, plastic-encased conductor that slips over two jumper pins.
Newer jumpers have a small tab on top that you can grip with your fingertips or with a
pair of fine, needle-nosed pliers. If your jumpers do not have such a tab, take care when
using needle-nosed pliers to remove or install a jumper; grip the narrow sides of the
jumper with the pliers. Never grip the wide sides because this can damage the contacts
inside the jumper, causing intermittent problems with the function controlled by that
jumper. Take care to gently grip, but not squeeze, with the pliers or other tool you use to
remove a jumper; you might bend or break the stake pins on the board.
The jumper at pins 1, 2, and 3 controls whether settings stored in CMOS nonvolatile
memory (NVRAM) are retained during a system reset. The jumper is used to restore the
system's CMOS and RTC to default values, as follows:
Changing Jumper Settings
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