For San Diego plant, Sony began with lean directives

''Our management style is neither the American way nor the Japanese way. It's the San Diego way.'' This remark is often heard from American and Japanese managers at Sony Corporation's sleek, low-lying plant here in the gently rolling hills of Rancho Bernardo. It is their way of describing the marriage of Japanese and American practices which had to take place to make the plant successful.

Sony came to Rancho Bernardo in 1972, at a time when major American manufacturers were moving key operations to Asia to take advantage of low wage costs. ''Unless we used Americans as Americans, not trying to turn them into Japanese, we had no chance of success at all,'' Sony chairman Akio Morita recalled in a recent interview.

Unlike most American companies setting up new operations, however, Mr. Morita supplied no bulky manual specifying in minute detail how the plant was to be organized and run. He gave just three instructions: Make top-quality products. Think not of short-term returns but of long-term profits. Remember that to make good products, the essential factor is the human being.

''From the beginning we knew we had the support of top management in Tokyo,'' recalled Masayoshi Morimoto, president and general manager of the plant. Mr. Morimoto, who is universally known throughout the plant as ''Mike,'' came to San Diego at the very beginning and has been here ever since. The goal was to turn out television sets that would be indistinguishable from those produced at Sony's Ichinomiya plant in Japan.

Mr. Morimoto, whose first job at the plant was to be in charge of the labor force, emphasized training in the widest sense. He also made sure that there was a constant flow of information from management to the workers and a corresponding feedback from the workers to management.

The work force was divided into 15 groups, each of which held frequent general meetings at which Morimoto would appear to report on how things were going and what was expected of the workers. Employees with complaints could go directly to their supervisors or dial a number to leave a tape-recorded message. ''We had no suggestion book, as we do in Japan, because we found that Americans would rather talk than write,'' Morimoto said.

One early problem with quality arose from the fact that workers were used to dropping their tools the moment the bell sounded at the end of their 40-hour workday. If some bolts were left untightened, if some small but essential part was missing, that was something to be corrected the next day. Inevitably quality suffered. In Japan, workers have the habit of finishing what they are doing and tidying up before they go home, even if it means staying 5 or 10 minutes extra for which they receive no overtime. How could these two customs be reconciled?

For weeks Sony's managers racked their heads. The answer, when it came, was extraordinarily simple, Morimoto recalled. ''We rang a warning bell five minutes before closing time. The workers had time to finish what they were doing and to tidy up before the main bell went off. That extra five minutes or so was on company time, but we were amply repaid in terms of improved quality.''

To this day the San Diego plant, which accounts for one-third of Sony's 2.5 million-a-year output of color TV sets, has no trade union, according to Richard Crossman, general manager for human relations and organizational development. Twice union organizers have forced plantwide votes on the question, and each time they have been defeated. Mr. Crossman has been with the plant since it opened and says he is impressed with the personal attention given by Mr. Morita and other top Sony management.

''This place is more like family than any other place I've worked,'' said Myrna Joy Huerta, a supervisor who started out as an assembly-line worker.

The company had never made any specific commitment of lifetime employment to its American employees, Mr. Morimoto said. But it did promise to make every effort to avoid layoffs. In the recession of 1974, that promise was tested. No one lost his job, and since then worker confidence in management has remained pretty steady, he said.

The current sales slump is the longest the Sony plant has experienced to date. In March this year, management was forced to put the work force on a four-day week rather than have to sack anyone. Still the work force remained loyal, although Morimoto confesses that if a longer sales slowdown occurs, he does not know what the company would do.

Other practices identified with Japan, such as having no executive dining rooms or parking spaces and maintaining an easy and visible relationship between management and the work force, are also popular with the workers, Mrs. Huerta said. ''We're on the line all the time,'' she said. ''And the workers respond, they want you to look good. Mike comes by the line also and talks to each group. No matter what you're doing, highest management knows you're there. That's what makes us family.

''We do discipline,'' she went on. ''But we do it as family. We try to convince a worker why what he had done was wrong, rather than telling him that what we insist on is right. I even got two people to quit, because over a period of time I was able to convince them that this was not the kind of job they wanted. But that's just two people out of thousands that have worked and are working here.''

In San Diego, quality always came first, Morimoto said. As for productivity, it took several years to bring the plant up to the level of factories in Japan. Retail stores say there has been no consumer resistance to US-made Sony products.

A walk through the immaculate plant makes it unmistakably clear that this is an American, not a Japanese, plant. In Japan, workers on the job are all dressed in company uniforms. They go about their jobs silently, with an almost frightening intensity. Here in San Diego there is none of that. The cleanliness is the same as in Japan, and the workers are quick and dexterous. But they are dressed as they please - some in uniforms, some not. Some have earphones and walkman sets. It is hard to describe the difference in attitude, but the Americans are, well, looser, more relaxed. Perhaps they feel more of a family atmosphere, as Mrs. Huerta said, but they remain individuals.