Hardware Reference
In-Depth Information
power supply and heavily shrink-wrapped or insulated where the connector lugs attached,
to prevent electric shock.
Thissolvedtheergonomicproblemofreachingtheswitch,butitstilldidn'tenableremote
or automated system power-up without special hardware. Plus, you now had a 120V AC
switch mounted in the chassis, with wires carrying dangerous voltage through the system.
Some of these wires are hot anytime the system is plugged in (all are hot when the sys-
tem's turned on), creating a dangerous environment for the average person when messing
around inside the system.
Caution
At least two of the remote power switch leads to a remote-mounted AC power switch in an
AT/LPX supply are energized with 120V AC at all times. You can be electrocuted if you
touch the ends of these wires with the power supply plugged in, even if the unit is turned
off! For this reason, always make sure the power supply is unplugged before connecting or
disconnecting the remote power switch or touching any of the wires connected to it.
The four or five wires are usually color-coded as follows:
•
Brown and blue
—These wires are the live and neutral feed wires from the 120V
power cord to the power supply. These are always hot when the power supply is
plugged in.
•
Black and white
—These wires carry the AC feed from the switch back to the power
supply. These leads should be hot only when the power supply is plugged in and the
switch is turned on.
•
Green or green with a yellow stripe
—Thisisthegroundlead.Itshouldbeconnected
to the PC case and should help ground the power supply to the case.
On the switch, the tabs for the leads are usually color-coded; if not, you'll find that most
switches have two parallel tabs and two angled tabs. If no color-coding is on the switch,
plug the blue and brown wires onto the tabs that are parallel to each other and the black
and white wires to the tabs that are angled away from each other. If none of the tabs are
angled, simply make sure the blue and brown wires are plugged into the most closely
spaced tabs on one side of the switch and the black and white wires on the most closely
spaced tabs on the other side (see
Figure 18.17
)
.
Figure 18.17
Power supply remote pushbutton switch connections.
