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Jumpers, Switches, and Connectors: Dell™ PowerEdge™ 4400 Systems Service Manual

Overview

This topic provides specific information about the jumpers on the system board. It also provides some basic information on jumpers and switches and describes the connectors and sockets on the various boards in the computer.

Jumpers and Switches—A General Explanation

Jumpers and switches provide a convenient and reversible way of reconfiguring the circuitry on a printed circuit board. When reconfiguring the system, you may need to change jumper settings on the system board. You may also need to change jumper or switch settings on expansion cards or drives.

Jumpers

Jumpers are small blocks on a circuit board with two or more pins emerging from them. Plastic plugs containing a wire fit down over the pins. The wire connects the pins and creates a circuit. To change a jumper setting, pull the plug off its pin(s) and carefully fit it down onto the pin(s) indicated.

NOTICE: Make sure the system is turned off before you change a jumper setting. Otherwise, damage to the system or unpredictable results may occur.

A jumper is referred to as open or unjumpered when the plug is pushed down over only one pin or if there is no plug at all. When the plug is pushed down over two pins, the jumper is referred to as jumpered. The jumper setting is often shown in text as two numbers, such as 1-2. The number 1 is printed on the circuit board so that you can identify each pin number based on the location of pin 1.

Figure 1 shows the location and default settings of the jumper blocks on the system board. See Table 1 for the designations, default settings, and functions of the system's jumpers.

Switches

Switches control various circuits or functions in the computer system. The switches that you are most likely to encounter are dual in-line package (DIP) switches, which are normally packaged in groups of two or more switches in a plastic case. Two common types of DIP switches are slide switches and rocker switches (see the following illustration).

1 Rocker switch 2 Slide switch

Each of these switches has two positions, or settings (usually on and off). To change the setting of a slide switch, use a small, pointed object such as a small screwdriver or a straightened paper clip to slide the switch to the proper position. To change the setting of a rocker switch, use the screwdriver or paper clip to press down on the appropriate side of the switch. In either case, do not use a pen, pencil, or other object that might leave a residue on the switch.

System Board Jumpers

Figure 1 shows the location of the configuration jumpers on the system board. Table 1 lists the function of these jumpers.

Figure 1. System Board Jumpers

Jumper	Setting	Description
EN PASSWORD	(default)	The password feature is enabled.
		The password feature is disabled.
CLEAR NVRAM	(default)	The NVRAM configuration settings are retained at system boot.
		The NVRAM configuration settings are cleared at next system boot. (If the NVRAM configuration settings become corrupted to the point where the system will not boot, install the jumper plug and boot the system. Remove the jumper before restoring the NVRAM configuration information.)

System Board Labels

Table 2 lists the connectors and sockets located on the system board.

SCSI Backplane Boards

Figure 2 shows the location of the connectors on the 1 x 8 and 1 x 6 SCSI backplane boards.

Figure 2. Connectors on 1 x 8 and 1 x 6 SCSI Backplane Boards

1 Cooling fan power cable connector (FAN) 2 Power connector (POWER) 3 System-board data cable connector (PLANAR) 4 Ultra2/m SCSI cable connector (SCSIA)

Disabling a Forgotten Password

The computer's software security features include a supervisor password and a user password, which are discussed in detail in "Using the System Setup Program" of the User's Guide. A password jumper on the system board enables these password features or disables them and clears any password(s) currently in use.

To disable a forgotten supervisor password or user password, perform the following steps:

1. Refer to "System Board Jumpers" for  the location of the password jumper (labeled "EN PASSWORD") on the system board.
   
   
2. Turn off the system, including any attached peripherals, and disconnect the system from its electrical outlet.

WARNING: Before you perform this procedure, you must turn off the computer and disconnect it from its AC power source. For more information, see "Safety First—For You and Your Computer."

3. Remove the computer cover.
   
   
4. Remove the interior support panel.
   
   
5. Remove the jumper plug from the EN PASSWORD jumper.
   
   
6. Replace the interior support panel and computer cover, and then reconnect the computer to an electrical outlet and turn it on.
   
   The existing passwords are not disabled (erased) until the system boots with the EN PASSWORD jumper plug removed. However, before you assign a new system and/or user password, you must install the jumper plug.
   

NOTE: If you assign a new system or user password with the jumper plug still removed, the system disables the new password(s) the next time it boots.

7. Repeat steps 2 to 4.
   
   
8. Install the jumper plug on the EN PASSWORD jumper.
   
   
9. Replace the interior support panel and computer cover, and then reconnect the computer to the electrical outlet and turn it on.
   
   
10. Assign a new system and/or user password.
    
    To assign a new system password using the System Setup program, see "Assigning a System Password" in the User's Guide. To assign a new user password using the System Setup program, see "Assigning a User Password" in the User's Guide.

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