Q T Wiles, regarded as a tough turnaround manager at Hambrecht & Quist, where he is a partner, has resigned as chairman and chief executive at MiniScribe Corp, Longmont, Colorado, saying that his family position does not now allow him to spend the time and energy required to act as chief executive through another difficult period in the disk drive industry: the news knocked 50 cents off MiniScribe shares, which may not sound much except that it left them at a lowly $4 even; the board accepted his recommendation that another partner at Hambrecht, Richard Rifenburgh, succeed him in the two positions.