Can a judge set aside or modify a valid final judgment?

sitting in equity, can set aside or modify a valid final judgment. [Citations.]" (Kulchar v. Kulchar (1969) 1 Cal.3d 467, 470 (Kulchar).) "A final judgment may be set aside by a court if it has been established that extrinsic factors have prevented one party to the litigation from presenting his or her case. [Citation.] The grounds for such equitable relief are commonly stated as being extrinsic fraud or mistake. However, those terms are given a broad meaning and tend to encompass almost any set of extrinsic circumstances which deprive a party of a fair adversary hearing." (In re Marriage of Park (1980) 27 Cal.3d 337, 342 (Park).) Thus, where the husband in a marital dissolution action concealed from the trial court that his wife could not attend the dissolution proceeding because she had been involuntarily deported, the husband "perpetrated a fraud upon the court as well as his wife." (Id. at p. 343.) The trial court therefore abused its discretion when it denied the wife's motion to vacate the judgment. (Id. at p. 347.)