MOHR Electrical Wire Harness Testing

Competitors Required:

1

Description:

This will be a troubleshooting task.  The objective will be to determine and locate bad antenna components, bad engine harness components, and bad cable terminations.

Teams will be presented with problematic multi-component cable assemblies and be responsible for locating and identifying failure points using high-resolution TDR data.  Faults may be intermittent, requiring the team to perform intermittent fault detection and location.

References:

CT-100B Operators manual (free account required)

MOHR AMC Site and MOHR AMC Training Videos

Tools, Equipment, and Materials Provided:

• CT 100B TDR Cable Analyzer
• CT100-AK-BNC RF connector Kit
• CT100-AK-PSP MOHR MIL-DTL-38999 adapter kit

Snap-on provided tooling (qty one in each of two pallets unless otherwise indicated): None

Procedures:

Test 1:  Identify Bad Antenna components

Procedure:

1. Discharge static from Antenna Connector A  (Known Good)
2. Select appropriate cabling and adapters for identified cable/termination.
3. Connect appropriate cabling to Device under Test (DUT)
4. Connect cable and DUT to CT100 TDR
5. Press Orange Autofit button on CT100.  CT100 will bracket entire cable length
6. Create high-resolution waveform of known-good sample
   1. Press the CT100 ‘Scan’ button
7. Discharge static from Antenna Connector B (Known bad)
8. Connect appropriate cabling to DUT
9. Connect cable and DUT to CT100 TDR
10. Perform Autofit if needed
11. Analyze Waveform differences between live trace (white) and known good trace (red)
    1. Look for any differences in amplitude between waveforms (impedance irregularities) between connection point and antenna.
    2. Adjust cursors and scale as necessary to analyze waveform at higher gain.
12. Move active cursor to fault location and notify judge

Figure 1: Test 1 Reference.  Typical Antenna installation.

Test 2:  Identify Bad Engine Harness (incorrect cable impedance)

Procedure:

1. Discharge static from Harness A (Known Good)
2. Select appropriate cabling and adapters for identified cable/termination.
3. Connect appropriate cabling to Device under Test (DUT)
4. Connect cable and DUT to CT100 TDR
5. Press Orange Autofit button on CT100.  CT100 will bracket entire cable length
6. Create high-resolution waveform of known-good sample
   1. Press the CT100 ‘Scan’ button
7. Discharge static from Harness B (Known bad)
8. Connect appropriate cabling to DUT
9. Connect cable and DUT to CT100 TDR
10. Perform Autofit if needed
11. Analyze Waveform differences between live trace (white) and known good trace (red)
    1. Look for any differences in amplitude between waveforms (impedance irregularities) between connection point and antenna.
    2. Adjust cursors and scale as necessary to analyze waveform at higher gain.
12. Move active cursor to fault location and notify judge

Figure 2: Test 2 Reference.  Multi-part cable harness and interconnects

Test 3:  Identify Bad / Loose connector

Procedure:

Judge will identify connector with known intermittent fault. 

1. Select appropriate cabling and adapters for identified cable/termination.
2. Discharge static from identified connector
3. Connect appropriate cabling to Device under Test (DUT)
4. Connect cable and DUT to CT100 TDR
5. Perform Autofit if needed
6. Analyze Waveform
7. Perform Envelope Plot to start intermittent Fault detection:
   1. Press the CT100 Blue button until the Main Menu appears.
   2. Select “Envelope Plot”
      1. An envelope plot will appear on screen and identify any impedance changes in real-time.
      2. Reset the Envelope Plot as needed if changes are made to scale or position.
      3. Physically manipulate the DUT (shake) to locate and quantify intermittent faults.  Distance to intermittent fault measurements can be made by moving the active cursor to the regions where major impedance changes occur.
8. Move active cursor to fault location and notify judge

Figure 3: Test 3 Reference.  Envelope Plot showing Pass/Fail impedances for 50ohm coaxial interconnect