Computer Consoles, a Massachusetts-based electronics firm with major operations in Irvine, has sold 40% of its computer leasing subsidiary to General Electric Credit Corp. of Stamford, Conn., for about $48 million. The subsidiary, based in Rochester, N.Y., leases computerized directory assistance systems widely used by telephone companies. Computer Consoles Chairman John F. Cunningham called the sale "one of the more significant steps to date in the restructuring and refinancing of our company," which began in 1985. Proceeds from the sale will be used to repay all existing bank debt, the firm said. The company's computer products division is based in Irvine.