The chairman of set-top box maker Pace is stepping down after a troubled end to his five years in charge of the company.Mike McTighe will be replaced by Allan Leighton, former non-executive chairman of the supermarket Asda. Leighton joins the board today and is expected to take over as chairman in summer.Shares in Pace have fallen sharply in recent months due to a number of factors including the Japanese earthquake and tsunami and economic weakness in Europe. The company lowered its profits guidance earlier this month and suffered a shareholder backlash over directors' pay when some 76m votes were cast against the company's remuneration report, compared with 127m in favour. The difficult period comes after years of strong growth from the company, which has benefited from the rise of pay-TV."I am proud to have played a significant part in Pace's turnaround over the past five years," said McTighe. "Despite the recent setbacks Pace is well positioned for the long term and I am confident it will continue to lead the global digital TV market."Leighton said he had been watching Pace through both its "ups and bumps" for 15 years."I've always felt there is a 'great technology company' in there," he said. "My task now with the management and the board is to deliver that 'great technology company' and the value that goes with it without the bumps."The process will start with a strategic review, he said.---RG