Book excerpt: Few repair manuals have a larger audience than this money-saving, do-it-yourselfer's guide. It contains all the information necessary to prevent, diagnose, or fix typical problems with audio & video cassette players & recorders popular in today's high-tech home. Homer Davidson's coverage ranges from basic cleaning & maintenance to performing repairs on everything from portable cassette players to state-of-the art digital audio tape players, all with only a few simple test instruments & hand tools. A complete glossary & list of manufacturer's addresses is included.