Power glitch can harm components

June 15, 1998|By MIKE HIMOWITZ

A friend called not long ago to complain that his new modem had suddenly stopped working.

I began my diagnosis with the usual, probing technical questions (Did you turn it on?) followed by the usual answers (Do you think I'm some kind of idiot?).

After a few minutes of this professional give-and-take, I determined that the modem was, in fact, dead as a doornail. Since new modems generally just don't stop working, I asked my friend whether there had been a thunderstorm between the time he had last seen the modem alive and the time he discovered the corpse. He recalled that a line of storms had moved through the area the night before.

"Did you have the cord to the phone line plugged into a surge suppressor?" I asked.

My friend was baffled. He said the computer was plugged into a surge-protected power strip, and so was the power cord from the modem.

Not good enough, I told him. To protect your modem you should have the phone cord plugged into a surge suppressor, too. That's because the phone circuitry in a modem is extremely sensitive - even to relatively tiny power spikes that can come through the phone lines when lightning strikes nearby.

To deal with this problem, many surge-suppressing power strips have two phone jacks in addition to the normal electrical outlets. One is for a cord from the power strip to the computer - another for a cord from the power strip to the wall. Inside the power strip, between the two jacks, is a suppressor specifically designed to protect modems. All of which brings me to my summer lecture on protecting your computer against the depredations of electrical gremlins.

This is a bad time of year for delicate electrical gadgets, which require a steady, clean supply of power. The major dangers are brownouts, blackouts, spikes and surges, which can cause problems that range from disk errors and minor data glitches to deep-fried computer systems.

Less or no power

Brownouts occur during heat waves when electric companies can't meet demand for electricity and lower the voltage slightly. Your computer can handle small fluctuations in current, but a serious brownout can make it behave erratically or even damage critical electrical components.

A blackout occurs when the electricity is cut off completely. This can happen when lightning strike takes out a transformer, or a falling tree hits a power line feeding your neighborhood. If your computer is writing to the hard drive when the power goes out, it can scramble your data or make the drive unusable. Worse yet, when the power returns, it's often accompanied by a voltage spike that can damage your circuitry.

Spikes also occur when lightning hits nearby transformers, power lines, or your TV antenna, sending a hot shot of current through your house wiring.

Even when there's no storm brewing, surges can occur when heavy-duty electric motors (air conditioners, refrigerators, power saws, etc.) cycle on and off.

Protection

Obviously, none of this is good news for your computer. But there are simple and relatively inexpensive steps you can take to protect your PC and its precious data.

The best solution is an uninterruptible power supply, or UPS, a battery backup box that sits between your computer and the wall outlet. Plug the computer into the UPS and the UPS into the outlet.

If the power goes out, even for a fraction of a second, the UPS TC battery kicks in automatically, preserving a steady flow of current if the interruption is over quickly, and giving you time to power down your equipment if the blackout lasts for a while.

How much time you get depends on how much you spend on the UPS. Inexpensive UPS units ($100 or so) can power a typical computer and monitor for 5 to 15 minutes. More money buys longer battery life and more power.

Better UPS models also condition your line and protect against brownouts, spikes and surges. Most come with four to eight outlets and a set of phone jacks. Not all the outlets are backed up by the battery, but they'reall protected with surge suppression.

If a UPS isn't in your budget, a good power strip designed for computers can protect your PC and modem against most electrical spikes. Make sure to find one that meets the Underwriters Laboratory 1449 specification.

Finally, even the best surge protection equipment won't work against a direct lightning strike. If a thunderstorm is passing by, it's a good idea to quit work and unplug your computer till it moves on.

Send e-mail to mike.himowitaltsun.com.

Pub Date: 6/15/98

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