Ask The Readers

Robert Lock, Richard Mansfield and Readers

We are grateful for the many readers who have sent questions and answers in to this column. Please keep on letting us know what your problems are and helping us solve the questions raised by other readers. Here is this month's exchange:

" ‘My Apple II: It does not compute!’ wrote to complain about excessive TV interference from his Apple II computer. Recently I've dealt with a similar problem — keeping an exceedingly noisy laser from interfering with my computer! Radio-frequency interference (RFI) can be a pesky problem, but the following measures may help the situation:

If you use your TV set for a computer display, be sure you disconnect the antenna while using the computer. This is especially important in apartment buildings, where many apartments share one antenna system! You can disconnect the antenna wires with a screwdriver, or insert an antenna/computer switch between the computer, antenna, and TV set. These switches are available at many electronics and TV repair shops.

Insert an "EMI filter" in series with the AC power cord. These filters are available from several manufacturers, notably Corcom. Interference frequently travels to other apartments through the power lines. Early Apples, with their switching power supplies, may be especially susceptible to this problem.

Try moving the computer to a different spot in the apartment, plugging it into a different AC outlet.

If desperate, you might try wrapping printer and disk cables, and perhaps the computer itself, in aluminum foil (!). Ground the foil to the computer chassis, the AC ground, or a cold water pipe.

Find out whether you're really the guilty party. I live in an apartment with a PET, and OSI, and a Motorola computer. The OSI runs with its case open much of the time, and the Motorola computer has no case. Neither machine causes perceptible TV interference." Mark Bernstein