I.B.M U.K. Ltd procure Switch-Mode Power Supplies to place in the computers they manufacture. These Power Supplies are tested to ensure that they meet a specified reliability target. Due to the high Mean Time To Failure (MTTF) the test duration required to verify the MTTF is in excess of three months. In an attempt to find a way to reduce the time required to ensure this requirement is met it was decided to investigate a selection of stresses from the point of view of their-effectiveness as a means of accelerating life tests. Subsequent to a theoretical exploration of the topics of Switch-Mode Power Supplies, Reliability and Accelerated Life Testing the power supplies were subjected to High Ambient Temperatures, High Relative Humidity, Power Cycling, Temperature Cycling and various conditions of electrical Stress. The effectiveness of these stresses was gauged by checking the power supplies' performance after various intervals during which they had been subjected to stress. It was discovered that high ambient temperatures have a measureable effect on electrolytic capacitors, which is physically related to the amount of energy to which the capacitors are subjected, to the extent that several capacitors failed during the tests without other damage being done to the power supply. It is recommended that further research be undertaken with a view to developing a relationship between capacitor degradation and power supply life test duration because, since the capacitors MTTF is greater than that of the power supply, failure due to degradation would indicate that the power supply had passed its specified MTTF
