A 27-year-old Arlington man whose convictions on rape, robbery and malicious wounding charges were overturned, was acquitted of the same charges yesterday after a two-day retrial.

After deliberating 7 1/2 hours over two days, an Arlington Circuit Court jury found D'Alesandro Barber not guilty of raping, robbing and cutting a woman whose first-floor apartment was broken into last summer and of burglarizing the apartment.

The 22-year-old woman had testified that Barber was the man who came into her apartment through a window, beat and cut her, and threatened to kill her.

Barber, a furniture store employe, initially was convicted of the charges in December by a jury that recommended a 45-year sentence.

His court-appointed attorney in the first trial, Edward C. Farstad, had acknowledged in court that he went to trial believing the attack occurred on the night of July 11, 1982, and told jurors his client did not have "a red-hot alibi." The incident actually took place around 2:45 a.m. that day, according to police.

Barber's conviction was overturned when the trial judge ruled that Barber did not have "effective assistance of counsel" and ordered the new trial.

Two defense witnesses testified this week that Barber was with them in Washington at the time of the attack. Barber's attorney, Richard C. Shadyac Sr., who said he was retained to represent Barber by the defendant's employer, based the defense on the testimony of those witnesses.

Barber, who has been held in the County Detention Center since his December conviction, was released immediately after the verdict.

The victim, who said she was so traumatized by the event that she did not remember she was raped until three months later, and Barber's wife both burst into tears after the jury announced its verdict yesterday afternoon.

Assistant State Attorney Helen Fahey based the prosecution's case on the identification given by the victim, physical evidence that Fahey said linked Barber to the crime and discrepancies in the testimony of the defendant and a cousin and friend of Barber's who corroborated his alibi.