Can a jury be impeached by an affidavit alleging misconduct of the jury?

The claims of error relating to alleged misconduct of the jury are based on the affidavits of some of the jurors. It is the general rule that a jury verdict may not be impeached by such affidavits except in the situation (chance verdict) set forth in subdivision 2 of section 657 of the Code of Civil Procedure. To this exception, the courts have added another: the concealment by a juror on voir dire of facts which would tend to show that he entertained a state of mind which would render him disqualified to serve as a fair and impartial juror. (Pollind v. Polich (1947) 78 Cal.App.2d 87, 92, 177 P.2d 63.)