Hacking the Xbox

Chapter 5 - Replacing a Broken Power Supply 75
1. Verify that the power outlet is functional by plugging a lamp
into it. Use a 100 watt lamp minimum to accurately simulate
the load of the Xbox.
2. Visually inspect the power cord for kinks and cuts.
3. Verify that the power cord plug is firmly seated in the Xbox
power receptacle, and that the Xbox still does not turn on
despite these checks.
4. Visually inspect the inside of the Xbox for char marks or
ruptured capacitors. If char marks are visible on the
motherboard, you may have to replace the Xbox
motherboard (i.e., buy a new Xbox). If there are char marks on
the power supply, most likely the power supply was
damaged and you may begin replacing it. (Keep in mind that
a power supply failure may also damage the motherboard,
so there is still a chance that the Xbox will not work once the
power supply is replaced.)
5. Verify that the main power supply connector and the front
panel circuit assembly connector are firmly seated. (The
location of the front panel circuit assembly connector is
illustrated in Figure 3-3 of Chapter 3, “Installing a Blue
LED.”) The power switch for the Xbox is connected to the
motherboard through the front panel circuit assembly
connector.
6. While the Xbox is off but still plugged, use a voltmeter to
verify that the 3.3V standby voltage (3.3VSB) is within
specification. Measure 3.3VSB by probing the sixth wire in
the power supply connector from the end closest to the
front panel, and any of the black wires on the power
connector. You can measure power supply voltages by
inserting the tips of a voltmeter probe into the free space
between the power wires and the power connector. (There is
a metal collar around the power wires inside the
motherboard power connector’s body.) If the value of
3.3VSB is not between 3.14 to 3.47 volts, you may need to
replace the power supply.
7. Press the power button on the Xbox to turn it “on”
(presumably, if the power supply is broken the Xbox won’t
do much). If the power supply makes noise or smokes,
unplug the box and proceed with replacing the power supply.
If the box seems dead, measure each of the primary voltages
coming from the power supply. The yellow wire should have a
voltage between 11.4 to 12.6 volts; the red wire should have
between 4.8 to 5.25 volts; and the orange wire should have
between 3.14 to 3.47 volts. (All of these voltages are
referenced with respect to the black wire.) Also, check that
the voltage on the Power OK signal (located at pin 12, the
pin farthest from the front panel) is above 3.1 volts.