Step 5: Troubleshooting Overview

Analyze the path(s) from input(s) to output(s).

This post is part of a series describing the generic, high-level troubleshooting process. These statements have not been evaluated by the FDA.

Previous Posts:
What is Troubleshooting?
Simplified Troubleshooting Overview
Step 1. Understand the correct inputs and outputs of the “black box.”
Step 2. Determine which output(s) are incorrect.
Step 3. Figure out which input(s) affect that output(s).
Step 4. Verify that those inputs are as expected.

Next Posts:
Step 6. Check all connections.
Step 7. What are the devices in those path(s) that change the data?
Step 8. Eliminate the devices that could not cause this output.
Step 9. Test the remaining devices.
Step 10. Repair/Replace faulty device(s).
Step 11. Fully test the system.

Step 5. Analyze the path(s) from input(s) to output(s).
Now that you have determined that you are looking at the right equipment (even if it is not where you started), you understand what the inputs and outputs should look like, deduced which outputs are not correct, know which inputs affect those outputs, verified that the inputs are as expected… its time to do a deeper dive into the inner workings of the equipment.

This step is a more detailed version of Step 3. If you didn’t have schematics, wiring diagrams, or other documentation in Step 3, you’ve probably already done this step. If you had paperwork, now is the time to physically look at the electron flow and see the routes, wires, switches, relays, circuits, pneumatics, motors, fuses, and everything else between input and output inside the actual equipment.

What is the path? What does it go through? Go back and read Step 3 if needed. At this step, we still don’t need to know what the “dots” do, we just need to see everything for ourselves. It is much easier if you learn the path and see what it looks like before you dive into the following steps.

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