Hardware Reference
In-Depth Information
This technique is also effective because so few parts are needed to make up a PC, and the known-
good parts don't always have to be the same (for example, a lower-end video card can be substituted
in a system to verify that the original card had failed).
Troubleshooting by the Bootstrap Approach
Another variation on this theme is the “bootstrap approach,” which is especially good for what seems
to be a dead system. In this approach, you take the system apart to strip it down to the bare-minimum
necessary, functional components and then test it to see whether it works. For example, you might
strip down a system to the chassis/power supply, bare motherboard, CPU (with heatsink), one bank of
RAM, and a video card with display and then power it up to see whether it works. In that stripped
configuration, you should see the POST or splash (logo) screen on the display, verifying that the
motherboard, CPU, RAM, video card, and display are functional. If a keyboard is connected, you
should see the three LEDs (capslock, scrlock, and numlock) flash within a few seconds after
powering on. This indicates that the CPU and motherboard are functioning because the POST routines
are testing the keyboard. After you get the system to a minimum of components that are functional, you
should reinstall or add one part at a time, testing the system each time you make a change to verify it
still works and that the part you added or changed is not the cause of a problem. Essentially, you are
rebuilding the system from scratch using the existing parts, but doing it one step at a time.
Many times, problems are caused by corrosion on contacts or connectors, so the mere act of
disassembling and reassembling a PC will “magically” repair it. Over the years, I've disassembled,
tested, and reassembled many systems only to find no problems after the reassembly.
Some useful troubleshooting tips include the following:
• Eliminate unnecessary variables or components that are not pertinent to the problem.
• Reinstall, reconfigure, or replace only one component at a time.
• Test after each change you make.
• Keep a detailed record (write it down) of each step you take.
• Don't give up! Every problem has a solution.
• If you hit a roadblock, take a break or work on another problem. A fresh approach the next day
often reveals things you overlooked.
• Don't overlook the simple or obvious. Double- and triple-check the installation and
configuration of each component.
• Keep in mind that the power supply is one of the most failure-prone parts in a PC. A high-
output (500W or higher) “known-good” spare power supply is highly recommended to use for
testing suspect systems.
• Cables and connections are also a major cause of problems, so keep replacements of all types
on hand.
Before starting any system troubleshooting, you should perform a few basic steps to ensure a
consistent starting point and to enable isolating the failed component:
1.
Turn off the system and any peripheral devices. Disconnect all external peripherals from the
system, except for the keyboard and video display.
2.
Make sure the system is plugged into a properly grounded power outlet.
3.
Make sure that a keyboard and video display are connected to the system. Turn on the video
