This was an informative application on how to go about testing terminated & un-terminated cables using the Huntron Instruments Tracker Model 30 & Scanner
The Huntron Tracker Model 30 and Scanner is an effective cable testing system as the testing technique can effectively find construction issues with cables. It also has the unique ability to test a cable single ended which is a blessing if they are attached to electronic equipment situated a large distance away. Comparative testing solutions require connection to both ends of the cable. It can test terminated cables and un-terminated cables
The Testing Technique
The Huntron Tracker Model 30 with Scanner uses the Huntron Workstation software for test development and execution. The pins of the Scanner are used to route the Tracker Model 30 signal to each of the pins of the cable. The Tracker Model 30 signal consists of a current limited sine wave that is applied across all devices. The Tracker Model 30 monitors change made to the sine wave by the device. The source and result sine waves are used to create voltage versus current waveforms called analogue signatures. Analogue signatures are stored for each cable pin on a good cable. These signatures are compared to signatures from pins on suspect cables.
Terminated Cables
The Huntron cable testing combination can test cables with electronic components at the other end of the cable. The components can be shorts, resistance, lights, non powered circuit cards etc.
Examples of terminated cables include
- Cable harnesses in a vehicle with a sensor/lights at the other end
- Adaptor cables with electronics
- Cables with terminating resistors
When testing terminated cables, the non terminated end of the cable is connected to the tester. The tester compares the signatures of the pins of the cable to a known good sample. It may be necessary to make common connections to the UUT on the other end of the cable.
Un-Terminated Cables
The Huntron cable testing combination can compare cables when both ends of the cable are available at the tester. If only one end of the cable is available at the tester testing is limited to pin to pin shorts.
Examples of un-terminated cable:
- Computer Cables
- Wiring Harnesses
When testing un-terminated cables and both ends are available, it is necessary to add bussed terminating resistors to each pin at the other end of the cables. The bussed node of the terminating resistors is connected to Common on the tracker Model 30. A typical value for the bussed terminating resistors is 50 ohm. Other values may be used on the construction of the cable and types of failures expected. Varying the resistance value from pin to pin allows check for miss-wired cables. LED's can be connected between the cable and the terminating resistors. Combined with selecting the correct test range, this allows for visual verification of continuity of each wire in the cable. Shorting all the pins of the other end of the cable can allow for seeing variations in the cables wires down to 1 ohm or lower.
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