Used to test for faults in components on assembled pc boards, CircuitTest 2000S performs its tests without power being supplied to the board and connects via a serial communications port to standard PCs. The board comes with software that transforms the PC into a troubleshooting tool with a variety of features. When combined with the 2100 Scanner Expansion, the system can quickly and automatically obtain component information from edge connectors, headers, or any other point on a board from 256 points up to 1024 points or more. This capability lets users troubleshoot assembled pc boards using various connectors, including existing bed-of-nails fixtures. Once connected to a PC, the system lets users input the name, type and location of components to be learned or tested using the Edit Mode to create a file for the board-under-test. Test defaults are automatic or can be modified for each test as the user desires. This customizable feature lets users enter up to a full page of notes for a board or component. And a Learn Mode lets the system learn both the numerical values of components in-circuit and their respective voltage/current signatures, with the results automatically stored in memory as a known good reference. The Test Mode then compares the learned board to that under test. Probes need only make contact to begin the testing process, and different tones signify pass or fail.