For those attempting fault isolation on computer motherboard power-ground short issues, the optimal technique should utilize existing test equipment available in the debug facility, requiring no specialty equipment as well as needing a minimum of training to use effectively. The test apparatus should be both easy to set up and easy to use. This article describes the signal injection and oscilloscope technique which meets the above requirements. The signal injection and oscilloscope technique is based on the application of Ohm's law in a short-circuit condition. Two experiments were conducted to prove the effectiveness of these techniques. Both experiments simulate a short-circuit condition on the VCC3 power rail of a good working PC motherboard and then apply the signal injection and oscilloscope technique to localize the short. The technique described is a simple, low cost and non-destructive method that helps to find the location of the power-ground short quickly and effectively.

Analyzing a failure on multiphase converter circuit on PC motherboards presents significant challenges due to the high number of nodes and the timing relationship between them. Typically a standard 4-channel oscilloscope can not capture the necessary timing relationship to effectively analyze the whole circuit. This article presents a simple and low-cost solution that can effectively help the users overcome the challenges of debugging multiphase converter circuit of PC motherboards.