Dell PowerEdge 1800 - Manual (Page 139)

Jumpers, Switches, and Connectors
139
Jumpers, Switches, and Connectors
This section provides specific information about the system jumpers. It also provides some basic
information on jumpers and switches and describes the connectors on the various boards in the
system.
Jumpers—A General Explanation
Jumpers 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 circuit boards 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.
Figure A-1 shows an example of a jumper.
Figure A-1. Example Jumpers
CAUTION:
Ensure that 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 A-2 shows the location and default settings of the system jumper blocks. See Table A-1 for the
designations, default settings, and functions of the system's jumpers.