By Anthony Olszewski
These notes are only meant to illustrate how I go about working on a machine. I'm not
anyone to work on their own system. In any event, if you do any damage, direct or
incidental, you are assuming complete responsibility and liability!
These notes are only meant to illustrate how I go about working on a machine. I'm not encouraging anyone to work on their own system. In any event, if you do any damage, direct or incidental, you are assuming complete responsibility and liability!
Let's start off with some terminology. The case with all the cards, floppy drives, motherboard,
drive, and, maybe, CD-ROM and tape backup is called "the system box." It is not the CPU and it
not the hard drive. The CPU (or processor) is the specific chip on the motherboard that is the
ringleader of the whole
little computer circus. The CPU is your 286, 386, or 486 chip actually on the motherboard. The
drive is the component that stores your programs and data. |
When you open up the case, removing the cover, the large circuit board fastened to the bottom (or side in a tower system) is the motherboard. The device that is about the same size as a 1.44 drive, but does not have any openings is your hard drive. Older hard drives could be the same size as 1.2 floppy drives (half-height form) or even double that (full-height form).
We're going to learn how to find a hardware component that has failed. Here we are ignoring, for the most part software inconsistencies and hardware incompatibilities. Right now, I'm not concerned with why your modem stopped working after you installed a sound card. Before us is a machine that was working and either stopped working, would not start working, or has started to freeze intermittently. Perhaps the machine is an unknown quantity, given away or purchased at a discount.
First off, if the machine is under any kind of warranty or if it belongs to somebody else -- STOP RIGHT HERE! Just notify them of the problem and let then decide how to handle it. If your tech efforts come to naught, quite likely, you will be blamed for breaking the machine. Any warranty might be voided.
If you are not the owner of the system carefully question the owner and\or operator about the machine and how the problem arised. Then ignore everything that they said. I only mean this as half a joke. People often have some wacky idea of what caused the problem or are lying. Very often, I discover, after examining the machine, that some drunk or clown worked on the machine, screwing it up. A good percentage of my business comes from "brotherinlawitis." I've also run across several computers that were clearly sabotaged. This could be random vandalism, an act of vengeance, or an employee bidding to get a new system.
Theft of components is far from unknown. Investigate the possibility of pilferage if out of the blue the system can't seem to find a hard drive. The same goes if the amount of memory suddenly decreases. The computer can't locate items if the're not there! With a modern ZIF (Zero Insertion Force) socket, the processor itself pops right out like bread from a toaster. A thief might even replace the stolen items with cheaper, less powerful hardware -- perhaps postponing indefinitely discovery of the crime.
If somebody tells you that they checked out the machine with a multimeter, either you are conversing with a highly trained technician or a boob. I've found that the more elaborate the description of the testing, the less qualified is the person doing the testing.
I don't pay much attention to beeps. Most machines give you one beep to let you know that everything was OK. COMPAQ gives two beeps as an OK. Some brands are silent as a sign that all is well. Various BIOS manufacturers use different numbers of beeps to signify problems, but I have a hard time counting the sounds, for they often repeat. Sometimes the number of repeats holds some meaning. Very often the whole thing is a wild goose chase. Just be aware that if your system starts chirping like a cricket on LSD, it has self-diagnosed a hardware error condition.
Turn the machine on and see what happens. Make sure that the power cord is plugged into a good source of power. If possible see if another system will work out of the same outlet. If you see nothing on the display, concentrate on the system box. Is the power LED lit? Are the floppy drive(s), hard drive(s) and keyboard LEDs lighting in the usual pattern? Can you feel the fan blowing air in the back? If these conditions are all true and you have made sure that the monitor is on and securely connected to the display adapter, try these tests. If your machine normally boots to DOS, hit enter twice then type in "dir" and then enter again. If your hard drive LED starts flickering, but you see nothing, the display is probably shot. Monitors are extremely dangerous to open and usually need to be replaced anyhow. If your machine boots to WINDOWS, start it from a boot disk to get directly to DOS in order to test the system. Very often, without a display, you can exit from windows by typing "ALT-F" then "x", then enter.
If the system still seems dead, or at least unconcious, now we've got to open the case. First unplug the power cord from the back of the machine. DON'T JUST TURN IT OFF! It's too easy to turn the machine back on by mistake. After you remove the screws holding the cover on the case, it's often necessary to start the cover to open with a regular screwdriver. I mean that you have to use a regular screwdrive to pry open the case a little. Study the case first and be gentle, slow, and methodical. THINK! You ain't crackin' a safe at the First National!
On old COMPAQ systems the fasteners really require a TORX screwdriver. In a pinch you might be able to get by with an ALLEN wrench or even a small standard screwdriver. Considering that you can buy the proper TORX tool at any auto parts store for a couple of dollars, trying to economize is a little silly.
|Most new cases don't use screws or other fasteners at all. Generally the front of the system (where the floppy drive and LED lights are) just pops out, being held in place by a number of springy, expanding-tension catch-gizmos (to use the technical term). The sides of the case will then lift and slide out.||