Classic Computer Magazine Archive COMPUTE! ISSUE 130 / JUNE 1991 / PAGE 75

Keep your power clean and pure. (PC maintenance) (column)
by Mark Minasi

PCs are big investments for homes or small businesses, so protecting that investment is important. The single biggest environmental threat to your PC comes from the very electric power that the machine needs to survive. Worse yet, power troubles don't come right out and announce themselves; they arrive in the guise of other problems. It's often hard to catch power problems in the act.

Have you ever experienced the following?

* A hardware problem that seems to jump around? One day it's memory, the next the disk, but it isn't repeated.

* A memory error that comes and goes?

* A PC that occasionally freezes up for no reason?

One of the most likely causes of these problems is either bad power itself or a bad power supply.

Surge of Power

AC power seems a fairly reliable thing; it keeps TVs, toasters, lamps, and the like running almost 100 percent of the time--at least in most of the U.S. And, it seems, one outlet's as good as any other. That toaster works just as well in the outlet on one side of the kitchen as in the outlet on the other side of the kitchen.

PCs should be as robust in their power needs, but they aren't sadly. Like all other computers, PCs have a fairly refined taste when it comes to electricity. You see, your PC needs power the way you and I need air; it'll die quickly without it, and if it's dirty, performance will suffer.

Problems with power fall into three categories: power surges, low voltage (brownouts), and no power (blackouts).

First, consider power surges. Surges come and go in a millisecond. You don't see them, they don't make the lights flicker, nor do they make the toaster burn your breakfast. They're too brief for any of those things. But every one of those zaps can damage chips in your PC.

Your PC's chips are composed of silicon crystals; crystals are highly organized molecules, groups of atoms frozen into a particular pattern. Add some unwanted energy--a power surge, in this case--and a few atoms fall out of place.

Once that happens, the chip's effectiveness is diminished somewhat because the fallen atoms generally remain out of place. This isn't always true, however. Some chips are self-healing to a certain extent, but much of this damage is cumulativ. One day, you'll get that final zap that pushes the last critical atom out of place, and your PC is history.

What can you do about power surges? There are three things: But power protection equipment, check that you're not causing any surges in your office or home, and leave the computer on all the time.

Don't Turn Your PC Off!

"What?" I hear you saying. "Leave the computer on all the time?" Yes, it sounds odd, but there are good reasons for it. Every time you turn on an electronic device, it experiences a momentary inrush current, a temporary surge of four to six times the usual current.

More specifically, the average PC system unit normally drawn around 60-80 watts of power. Such a PC would see a brief surge of up to a half kilowatt of power, not a plan for PC happiness. (You can find out more about this in PC Power Protection, by Mark Waller, published by Howard Sams in 1989. It's a bit techie, so some of it is rough sledding, but it's packed full of power facts and worth picking up.)

Some people explain it this way: When do light bulbs most often burn out? Answer: When they're first turned on. That's a bit of an oversimplification, but the general rule is that electronic devices, PCs included, are happiest when left on all the time. Some of the most reliable electronic things in your house are left on all the time, including the thermostat that controls your house's temperature, electric clocks, and TVs. (TVs? Yes. Part of your TV is active all the time, like the part that responds to the remote.)

That's why I say to leave your PCs on 24 hours a day, seven days a week. We've done it at my company for years. Just leave the system unit on and turn the monitor off, turn the screen intensity down, or use one of those annoying automatic screen blankers so the monitor doesn't get an image burned into it. Turn the printer off, also.

Now, not all of you will be convinced to leave your machines on 24 hours a day. But here's a related tip that everyone should heed. I see lots of users who plug everything into their surge protector, then use the surge protector's on/off switch as a kind of master on/off switch for the PC and peripherals.

This has the unfortunate effect of causing all the power-on surges from the monitor, PC, and printer to happen at the same time, a worse situation than powering them up separately.

To remedy that, some companies sell so-called power directors, those slim boxes that sit above the system unit and below the monitor. They cause a very short delay between the monitor power-up, printer power-up, and system unit power-up, so their surges don't interact.

Of the reasons to leave your computer on all the time, perhaps the most compelling is to protect your hard disk. One important component of your hard disk is the rotational motor, the motor that keeps the disk spinning at exactly 3600 rpm. You know from real life that it's a lot harder to start something moving than it is to keep it moving. (Ever push a car?)

Similarly, the rotational motor finds it much easier to keep the disk spinning than to start it spinning. When a hard disk won't start spinning on power-up, it's called stiction, and it's one cause of drive failure.

And there's another reason why you should keep the power on, as far as the hard disk is concerned. The initial power surge runs through everything, including the hard disk head. Let's suppose you don't park your hard disk head, so the head just ends up wherever it was when you turned the machine off. Now the surge goes through the head. It ends up blasting the data that happens to be sitting under the head with a "Bleahhh!" The surge blurs the data under the head. Obviously, autopark drives don't have this problem.

I know--you're having trouble believing that your drive's motor is happier working without a rest. But consider this: Do hard drives tend to fail more upon startup or at some random point during the day? Most failures that I've seen happen upon startup or boot time. Leaving the disk spinning avoids those troubles.

All of this advice is only useful, by the way, if (1) your machine remains fairly cool, 80 degrees or below, (2) you have fairly reliable power (there's no sense trying to leave your computer on all the time if you're going to end up losing power once a day anyway), and (3) you have decent surge protection--the next topic.

Shielding from Surges

Surges are caused either by noise on the power lines or by other devices on your power circuits. For example, copy machines feed a fair bit of noise into the system; so do power tools and big motors, like the ones you see in refrigerator or air conditioner compressors.

That means that surges occur on a daily or, in some sites, an hourly basis. If the PC's power isn't properly isolated, it'll see surges every time the coffee maker, refrigerator, copier, or any other large power drain comes online.

Since we can't see surges, we tend not to be aware of just how common they are. So special devices have been invented that will monitor surges and report on their frequency of appearance. Such power line monitors cost a pile of money--some can run $15,000 or more.

Most of us can't afford that, of course, but there's a much cheaper power line monitor from Tasco (2875 West Oxford Avenue #5, Englewood, Colorado 80110; 303-762-9952; $130). Called the AC Line Monitor, it plugs into any power outlet. Lights indicate the voltage level being delivered at the moment, as well as surges. Since surges don't la long, the surge light comes on after a surge and stays on until you push the reset button. The monitor even makes an annoying buzz when a surge happens.

Once you've seen how common surges are, what can you do about them? Three approaches to surge protection are seen in the industry today:

* Inexpensive surge protectors use one-shot, kamikaze components to protect you from a single surge.

* Transformer-based systems are a bit more expensive but are reusable.

* Uninterruptible Power Supplies (UPSs) break down the power, eliminate the surges, and reform the power into textbook clean AC power.

Many of us have sit-outlet power strips that are sold as surge protectors, costing from $20 to $100. Surge protectors are built around a device called a Metal Oxide Varistor, or MOV.A MOV is a device that can shield your PC from a quite a lot of unwanted power for a fairly low price. But when it reaches its limit, it essentially disappears from the circuit--it affords no surge protection once it's dead--and allows the surges to pass right on through to the PC.

That's the troublesome part about a surge protector: It dies eventually, and there's dno easy way to find out when it's dead. Many of you reading this article may have surge protectors that are totally useless. There are some surge protectors that have a light on them that indicates whether the surge protector is still working or not. Surely this is enough surge protector insurance? Sadly, it isn't. When the light is out, the surge protector is surely dead. But if the light's still on, the surge protector could be useless.

It's amazing that so many surge protectors are sold when they provide such ephemeral protection, but there's a good reason. They're inexpensive, and nobody bothers to explain to consumers exactly what they are--or are not--buying.

Maybe that's why power conditioners aren't very well known, even though they're probably your best but in power protection devices. A power conditioner is built around a transformer, and a transformer will, among other things, absorb an essentially unlimited numvber of surges. A power conditioner will additionally adjust your AC voltage up or down to compensate for variations in the power that your local power utility is providing. Why is this important? Well, where I live, for example, the local utility has some trouble providing a full 120 volts in the middle of summer, when electric demand is at its peak. So it compensates by dropping the voltage to 110 or 115 volts. I know when this happens because the power conditioner under my desk clicks when the input voltage changes. My PC's got nothing to worry about, however, because the power conditioner automatically steps the voltage back up to 120.

That's the beauty of power conditioners; they protect you from surges and low voltage all in one package. The bad news is the price. They're about three times the price of a surge protector. One good powe conditioner, for example, is the Tripp Lite LC1200 (Tripp Lite, 500 North Orleans, Chicago, Illinois 60610; 312-329-1777; $249), which can be found discounted at around $150.

A power conditioner protects you from the first two power problems, surges and low voltage. But what about the third--no voltage, a blackout? That's for next month.