Jordan Kitt's Music Inc., which has sold pianos and organs for more than 70 years, is changing its tune and moving into other types of keyboards.

According to William J. McCormick Jr., chairman and president of the 17-store chain, Kitt's will begin marketing personal computers near the end of this year. The expansion will cost $500,000 to $1 million, he said.

The music company will offer personal computers in the $1,000-to-$5,000 price range, McCormick said, avoiding the depressed lower-end market in computers priced at $100 to $500. Kitt's will be aiming especially at shopping mall customers, he said.

As it does now for purchasers of musical instruments, Kitt's will offer instruction for computer buyers, he said.

McCormick said his company, headquartered in College Park, will sell computers at three stores in Montgomery, Prince George's and Fairfax counties.

The Fairfax and Montgomery stores will be computer-and-music shops converted from present facilities, he said, adding that Kitt's will open a new computers-only store at a Prince George's County site still being negotiated.

Even though personal computers in this price range usually are used by persons involved in business, McCormick said his company hopes to introduce more-sophisticated machines to ordinary consumers. The difficulty in selling more-advanced computers to people with little computer experience, McCormick said, is that no one has convinced the consumer he can use them.

But with proper instruction provided, sophisticated machines can be more readily accepted, he said.

McCormick said Kitt's computer stores will not carry common video games or telephones, but will feature most of the leading personal computer brands.

Kitt's will test the concept of computer-and-music stores for a year before deciding whether to adopt that format or keep its music and computer stores separate, he said.

McCormick said Kitt's also was studying the feasibility of acquiring local computer businesses, but declined to say which enterprises were under consideration.