A federal judge last week approved class-action status for a sex-discrimination lawsuit brought by female technicians at five CBS-owned stations. The action, approved by U.S. District Judge Donovan Frank, includes about 175 female technicians who allege systemic denial of opportunity for promotion, overtime and training and that the stations allowed sexually hostile work environments. In his ruling, the judge urged the parties to avoid a trial and settle the case. The station defendants are WCBS-TV New York, KCBS-TV Los Angeles, WBBM-TV Chicago, WCCO-TV Minneapolis, WWJ-TV Detroit and WFRV-TV Green Bay, Wis. A plaintiff alleging similar facts won a finding of discrimination last year from the Equal Employment Opportunity Commission. CBS says it is studying the decision.