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Jumpers, Switches, and Connectors: Dell™ PowerEdge™ 1550
and PowerApp™ 120 Systems Service Manual
This section 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 provide a convenient and reversible way of
reconfiguring the circuitry on a printed circuit board. When installing replacement parts
or reconfiguring the system, you may need to change jumper settings on the system board.
You may also need to change jumper and/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.
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.
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
Table 1. System-Board Jumper Settings
| Jumper |
Setting |
Description |
| RSVD_DEBUG |
 |
(default) |
Reserved (do not change). |
| RSVD_PWR |
|
(default) |
Reserved
(do not change) |
| CMOS CLR |
 |
(default) |
The configuration settings are retained at system boot.
The configuration settings are cleared at next system boot. If the 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 configuration information. |
| PASSWD |
 |
(default) |
The password feature is enabled.
The password feature is disabled. |
| FLASH DISABLE |
|
(default) |
Reserved (do not change). |
 jumpered
 unjumpered |
Table 2 lists the connectors and sockets located on the system board.
Table 2. System Board Connectors and Sockets
| Connector
or Socket |
Description |
| BACKPLANE |
Backplane board interface cable
connector |
| BATTERY |
Battery connector |
| SERIAL |
Serial port connector |
| BANKx_DIMM_n |
DIMM sockets |
| ETHERNET_n |
RJ45 Ethernet NIC connector |
| KEYBOARD/MOUSE |
Keyboard (and mouse, with Y-cable)
connector (front) |
| KEYBOARD |
Keyboard connector (back panel) |
| MOUSE |
Mouse connector (back panel) |
| POWER |
Power connector |
| PROCESSOR_n |
Microprocessor ZIF socket |
| SCSI |
Ultra3 SCSI host adapter connector |
| USB_n |
USB connector |
| VGA |
Video connector (back and front
connectors) |
Figure 2 shows the location of the connectors on the back of
the SCSI backplane board.
Figure 2. SCSI Backplane Board
Connectors
 |
| 1 |
Thumbscrew |
| 2 |
SCSI backplane board |
| 3 |
Power connector (POWER2) |
| 4 |
Control panel connector |
| 5 |
CD-ROM interface and
power connector |
| 6 |
Diskette drive interface
and power connector |
| 7 |
Interface and power connector to hard-disk drives (3) |
|
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.
NOTICE: See "Protecting Against Electrostatic Discharge."
- Turn off the system, including any attached peripherals, and disconnect the AC power
cable from its power source.
- Remove the optional front bezel, if it has one.
- Remove the top cover.
- Refer to "System Board Jumpers"
for the location of the password jumper (labeled PASSWD) on the system board.
- Remove the jumper plug from the PASSWD jumper.
- Replace the top 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 PASSWD
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
and/or user password with the jumper plug still removed, the system disables the new
password(s) the next time it boots. |
- Repeat step 1.
- Install the jumper plug on the PASSWD jumper.
- Replace the top cover and
then reconnect the computer and peripherals to their electrical outlets and turn them on.
- Assign a new system and/or user password.
To assign a new system and/or user password, see Using the System
Setup Program.
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