3 Preparing to Work on the System



This chapter explains important steps to be performed before you replace field- replaceable units (FRUs). Topics covered in this chapter include the following:

Halting the System

Before you replace FRUs, you must halt the system in an orderly manner.

Caution -

You must halt the system in an orderly manner. When the operating system or any other standalone program has already booted, do not use the
L1-A keys to halt the system. Abruptly aborting program execution may cause damage to data files.

To Halt the System

    1. Preparation.
      a. Save any files you are presently editing.
      b. Quit from any applications that will lose information when the system halts.
    2. Become superuser.
      a. Enter /bin/su to become superuser.
      b. Enter the superuser password.
    3. Halt the system.

    Enter /usr/etc/halt. The system displays system halt messages followed by the > Monitor prompt.

    4. Turn off the power.

    Turn off the power in this order:

      a. External devices (if you have any)
      b. System unit
      c. Monitor

Caution -

Make sure your system is shut off. The green LED at the front of the system unit should not be lit, and the fan should not be running. Do not disconnect the power cord from the system unit's power outlet or the wall outlet. This connection provides the ground path necessary to safely remove and install SBus cards and internal components.

Halting a System That Does Not Respond Normally

To halt a system that is hung, or frozen, and unresponsive to commands:

    1. Press L1-A.

    The system displays the system boot prompt.

Note - On some keyboards, L1-A appears on the front face of the Stop key. On a system that has a terminal as a console, rather than a Sun keyboard and bitmapped monitor, you must press Break instead of L1-A to obtain a boot prompt.

    2. Enter n

    The system displays a help message and an ok prompt.

    3. Enter sync

    The system displays panic and boot messages.

    The sync command helps prevent the system from losing data that was not preserved when the system hung.

    4. Wait for the login prompt.

    Wait until the system boots and displays a system login prompt.

    5. Turn off the power.

    Turn off the power in this order:

      a. External storage devices (if you have any)
      b. System unit
      c. Monitor

Caution -

Make sure your system is shut off. The green LED on the front of the system unit should not be lit, and the fan should not be running. Do not disconnect the power cord from the system unit's power outlet or the wall socket. This connection provides the ground path necessary to safely remove and install the printed circuit boards and components.

The following example shows how to halt a hung system:

For additional information on the halt procedure see Chapter 1 of the Sun System & Network Managers Guide and also the System & Network Administration manual.

Tools Needed

To remove and replace FRUs, you will need the following tools and materials:

Disconnecting Peripherals

If your system unit has external storage devices connected to it, detach the device's SCSI connector from the back of the system unit.

To detach external storage devices from the system unit:

    1. Press in on the finger clips on the connector connecting the device to the system unit.
    2. Pull the connector off.

This action disconnects the SCSI cable from the system unit.

Opening the System Unit

Figure 3-1 shows how to open the system unit. The latch buttons at the sides allow the unit top and unit bottom to disengage.

To open the unit and gain access to the FRUs inside the system unit:

    1. Turn off the power to the system unit.
    2. Remove the top section from the system unit.

    To remove the top section from the system unit do the following in sequence (see Figure 3-1):

      a. Remove the screw holding the lock block to the back panel.
      b. Position the system on the table so that there is enough space to lay the top section of the unit flat in front of the bottom.
      c. Grasp the unit top with your fingers over the latch buttons at the sides. Press down on the unit top and depress the latch buttons.
      d. Rotate the unit top up and toward the front panel. Lay the unit top flat on the table. The unit top and bottom are still connected by the power and data cables leading from the disk drive(s) and power supply in the unit top to the main logic board in the unit bottom.

Note - The unit top contains the power supply and disk drives (see Figure 3-2) and is the heavier of the two sections.

Warning -

Before powering up your system again, be sure to close the unit. See "Closing the System Unit" towards the end of Chapter 5.

    Figure 3-1 Opening the System Unit

Figure 3-3 and Figure 3-4 show the various components of the system unit. The main logic board occupies the unit bottom. The SBus cards plug into the main logic board. Four slots on the main logic board accept the Single Inline Memory Modules (SIMMs).

The unit top contains the power supply in the rear of the top section. Mounted just in front of the power supply is the bracket for both the hard disk drive and the diskette drive. If you have upgraded your SPARCstation IPX from a SPARCstation IPC you may have an earlier version of the disk drive bracket. See Appendix F for information on earlier model disk drive brackets.

Caution -

The lithium battery molded into the NVRAM, located on the main logic board next to the Boot PROM, may explode if mishandled or attempts are made to recharge it or disassemble it.

Caution -

Electronic parts may be damaged by static electricity if touched by a person not wearing a properly grounded wrist strap.

    Figure 3-2 System Unit and Subassemblies

    Figure 3-3 Top View of System Unit and Subassemblies

Attaching a Wrist Strap

A wrist strap (or grounding strap) provides grounding for static electricity between your body and the chassis of the system unit. Electric current and voltage do not pass through the wrist strap.

After you have opened the system unit and before you handle any internal components, attach the wrist strap to your wrist and to the metal casing of the power supply in the top of the system unit. Parts that require the use of a wrist strap are packed with one.

Caution -

If you do not wear a wrist strap, boards, cards and modules can be damaged by harmful electrical charges.

To use a wrist strap:

    1. Wrap the grounding strap twice around your wrist.

    Make sure the adhesive side is against your skin.

    2. Attach the end with the adhesive copper strip to the metal casing of the power supply in the top of the system unit (see Figure 3-2).