Welcome to our special report on computer servicing. Contrary to the fears of some of our readers, we do not plan to become another computer book.
In response to a recent questionnaire in this magazine, more than 80% of those who responded said that they want to read articles about servicing televisions in ES&T. We have no plans to do anything other than continue heavy coverage of TV servicing for those readers, with at least one article on that subject in every issue.
On the other hand, the population of personal computers is growing, and a lot of you want to read about servicing them-nearly 50% of those who returned the questionnaire, in fact. That's the reason for this special report. (For more on what our readers' survey revealed, see the Editorial on page 4.) Here's what the EIA had to say about personal computers in the 1987 issue of its publication, Consumer Electronics Annual Review:
" ... many manufacturers feel that by the year 2000, consumers will be spending more for home information processing and communications equipment than they will for purely entertainment products.
"Functions normally associated with a business office are performed in nearly every home. Income and expenses have to be kept track of, appointments to be made and messages to be taken and delivered. There's correspondence to be handled and, where there are students in the house, reports to be researched and written. For many years businesses have turned to electronics for products that simplify and improve information handling. Now, similar, though much more affordable and often less complex products that bring office like efficiencies to the home are being made and marketed by consumer electronics manufacturers.
"Almost 3.8 million personal computers were sold for home use last year and, with software and accessories, represented a $3.8 billion business. Today a personal computer housed in a typewriter-like console, with brain power equal to that of the room-sized multimillion dollar computers of the 1960s, can be purchased for less than $300. Prices, however, can run up to $2,000, depending on the functional capabilities, memory power and accessories included.
"The term 'computer literate' has become more than a catch phrase to describe those in the know. It's now a requirement for graduation from many high schools and colleges, and some colleges include the cost of a computer for each student in their tuition. 'Keyboarding,' or how to interact with a computer, is being taught at the elementary grade level.
"In the home, computers are used for financial and family function planning, record keeping, educational enrichment, training and word processing. Connected to the telephone lines through a built-in or add-on device known as a modem, computers provide access to outside data banks containing a vast variety of research information, along with business, professional and transportation directories, games and message centers that serve as electronic bulletin boards for computer owners with similar interests.
Modems also let computers be used for home shopping, banking and travel reservation services that are now becoming available." This special report is intended to bring together several types of important information on computer servicing, in particular: a concise overview of the development of personal computers and approaches to servicing; some specific problems and cures for the Apple II+ personal computer; specific suggestions on servicing the Commodore disk drive; a comparison and contrast between active and passive breakout boxes, describing the advantages and drawbacks of each; and a discussion of how to use a logic probe in computer servicing.
The usefulness and ease of use of personal computers is increasing rapidly; at the same time, the cost is coming down precipitously. Their numbers will continue to grow, and many of those computers will need servicing at some time in their lives. We hope you benefit from this special report.
Also see: Troubleshooting microprocessor-based circuits--Part I