The book is devoted to the issues of repair and maintenance of pulsed secondary power supplies, which are used in almost all modern imported and domestic radio-electronic equipment. The book examines theoretical issues of design and calculation of pulsed power supplies, describes in detail the basics of their circuit design and operating principles. Various methods of stabilizing output voltages, methods of protecting power supplies from overloads in secondary circuits are described, and methods of turning off power supplies when output voltages increase above established limits are also considered. Power supplies of modern computers of AT and ATX form factors are considered as examples. The relevant sections discuss typical faults and methods for finding and eliminating them. The book is intended for specialists involved in the repair and maintenance of computer equipment and other electronic equipment with pulsed secondary power sources, trained radio amateurs and students of higher and secondary specialized educational institutions.