core Estimated learning time: 8 h

EC-13.6 Fault Diagnosis, Evidence and the Report

You can diagnose a fault by halving the problem rather than by inspecting it, record what you did so that someone else could repeat it, write a report that answers the original question, and say honestly what the session did not establish.

Before:S4-1. Analog CircuitsEC-8. Measurements, Instrumentation and Experimental MethodEC-9. Microcontrollers and Embedded SystemsEC-19. Introduction to Electronics, Design and MakingUnlocks:EC-14. Engineering Design and System IntegrationEC-16. Ethics, Safety, Sustainability and Standards

Diagnosis is a method rather than a talent, and the method is the same whether the fault is in a circuit, a program or a process. This topic states it explicitly and then attaches the evidence and reporting habits to it, because a diagnosis nobody recorded is a diagnosis that will be made again next week by the same person.

Work through these

  • Halving the problem instead of staring at it

    Find a point midway through the chain and establish whether the signal there is right. Each such test removes half the possibilities, which finds a fault in a handful of measurements rather than by inspection.

    NPTEL: Research Methodology (IIT Madras) · Course
  • Changing one thing at a time, and putting it back

    Two changes at once make the result uninterpretable, and a change left in place becomes an undocumented feature. Undoing each change that did not help is what keeps the state of the setup known.

    NPTEL: Research Methodology (IIT Madras) · Course
  • The fault log, and why it is worth keeping

    What was wrong, how it was found and what fixed it. A page of these accumulated over a course is the most reusable thing a laboratory produces, because the same faults recur.

    NPTEL: Research Methodology (IIT Madras) · Course
  • Evidence a reader can check

    Captures with their settings visible, tables with units and uncertainties, photographs of the actual setup. The test is whether a reader could tell a correct result from a plausible one.

    NPTEL: Measurement and Instrumentation (IIT Guwahati) · Course
  • The report that answers the question you started with

    Purpose, setup, method, results with uncertainty, and a conclusion that addresses the objective. A report that describes what was done without answering the question has missed its own point.

    NPTEL: Technical Communication for Engineers (IIT Roorkee) · Course
  • Saying what was not established

    The conditions you did not test, the range you did not cover, the assumption you had to make. Stating these is what separates an engineering report from an assertion, and it is the part most often omitted.

    NPTEL: Research Methodology (IIT Madras) · Course

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