An analog signature analysis primer

摘要

Analog signature analysis (ASA, also known as V-I testing) is an elegant, powerful fault-diagnosis technique for printed circuit boards, and is the method of choice whenever circuit diagrams and documentation are lacking. In these situations, comparative analog signature analysis can be used by matching the analog signatures of a known-good printed-circuit assembly with those of a suspect one; signature differences can indicate a potential problem. A major advantage when testing a board with a V-I tester is that the device under test doesn't need to be powered up. This makes the a vertical trace deflection on the display, while the voltage across the component is shown as a horizontal trace deflection (X axis = voltage; Y axis = current). The resultant trace on the display is called the "analog signature."