Troubleshooting
Troubleshooting Overview
So, you have a computer with a problem. Where do you start? Sometimes, that answer is obvious. If you have a machine that won't power on, the first thing to check is if the power is connected. Then, check the power supply. Is the voltage switch set correctly? Is the power supply on-off switch in the on position? If the answer to these is yes, the next thing to do is try a known good power supply. If that works, you have found the problem. Occasionally, that won't work either, but then you have reason to suspect a bad motherboard; there aren't too many other possibilities.
More often, however, the source of the problem won't be so obvious, or it will seem obvious, but nothing you try works. While experience helps more than anything else, there are certain principles and concepts that ease the job of diagnosing a computer.
All Might Not Be What It Seems
All might not be what it seems. The best example is when the computer locks up, as discussed in Chapter 9, "Input Devices." Many people see that the pointer freezes and assume that their mouse just broke. They buy a new mouse, and unless the computer locks up immediately, they think the the problem is solved. Here's what happened to me on two laptops. The machines wouldn't go into standby or hibernation, and attached printers stopped printing. In every case, the error messages blamed the problem on the driver of an item that was working normally: in one case, it was the keyboard driver; in another, a COM port driver; in the third, a network adapter driver. The problem, however, had nothing to do with these drivers. In fact, keyboard and COM port drivers rarely, if ever, exhibit any problems. The problem in each case turned out to be the recent installation of a USB device; a scanner, a Web cam, and a hard drive. Even with the device disconnected, the mere presence of one of these drivers in the system caused these problems. Uninstalling the drivers, and in the case of the Web cam, removing every vestige of the software, solved the problem. The oddest thing is that all three of the USB devices worked perfectly.
So, to repeat the question, how do you know where to start? For those who work in technical support for certain notorious hardware and software companies, the answer is anywhere but with their product. However, if you're trying to find the real reason, the first thing you'll have to accept is that a given problem could be caused by almost any component in a system. Therefore, the troubleshooting procedure should start with the most likely culprit and then proceed to the next most likely once the most likely has been ruled out. If nothing is obvious, there are other ways to find the problem, which we discuss throughout this chapter.
Note There comes a point at which it is not worthwhile to diagnose a problem, such as when you'll be spending more time and/or money than the computer is worth, or when it would be easier to simply back up the data, if desired, format the hard drive, reinstall the OS and programs, and restore the data.
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