Troubleshooting Procedures; Troubleshooting A Power Supply Problem - Texas Instruments Extensa 450 Series Maintenance Manual

Try rebooting the system (CTRL-ALT-DEL); restore system from diskettes, if
necessary.
If the computer is capable of running the Setup program; check the serial and
parallel port configurations, and other features that may affect system
operation.
Run Diagnostics to further isolate problem area (See Paragraph 5.3.5).
For indicated hardware failures, cycle power and repeat self test to verify that a
hard failure has occurred.
Remove and replace suspect hardware (as described in Section 6 of this
manual) and retest the system using the diagnostic tests as described in
paragraph 5.3.5.
The detailed block diagram, shown in Figure 5-2, is useful in performing fault
analysis of various internal subsystems. For example, an LCD hardware problem
can be traced to either the LCD, Inverter Board, VR Board, or Battery Board. Other
subsystem problems can be isolated in a similar fashion using the detailed block
diagram as a troubleshooting tool.
5.3

Troubleshooting Procedures

The built-in self test program and the disk resident diagnostics program (PC-Doctor)
are useful tools in computer troubleshooting. However, if the computer has a power,
keyboard or display problem, you first solve this problem before running
diagnostics. If the computer powers up and displays messages on the LCD or emits
a series of beeps, skip to Paragraph 5.4.3 for further instructions.
5.3.1

Troubleshooting a Power Supply Problem

If the computer does not power up when the Power Switch is set to the ON position,
you most likely have a malfunction in the power subsystem (loss of power at the AC
Outlet, faulty AC Adapter, discharged Battery Packs, or faulty Power Supply Board).
With a power problem, all LEDs are extinguished, the LCD screen is blank, the
system does not respond when the standby switch several times consecutively and
no drive activity can be heard. The computer is unable to load software and
displays no visible signs of activity.
To fault isolate a power problem, check the following:
AC Adapter and Battery- Plug in the AC adapter and double check all
connections on the Adapter and computer. Ensure that the Notebook Power
switch is set to the On position and that the system is not in Standby or sleep
mode.
Measure the voltage at the AC Outlet or plug in a known good appliance (EG. a
lamp) to verify that voltage is present. If the voltage is O.K., try replacing the
AC Adapter
Check to see that the battery pack is installed correctly (try using a recharged
battery pack if batteryis discharged).
Troubleshooting 5-3