Troubleshooting flow: In a structured repair process, internal IC failures are most likely to be recognized during which phase?

Introduction / Context:
Professional troubleshooting typically follows a staged workflow: verification of symptoms, diagnostic testing, isolation of the faulty block, component-level repair or replacement, and final test. Recognizing when internal IC faults become evident helps technicians choose the right tools and tests at the right time.

Given Data / Assumptions:

• A standard, methodical troubleshooting process is used.
• Diagnostic activities include applying known stimuli, measuring expected responses, and comparing to specifications.
• Isolation further narrows the fault to a board area or subcircuit after diagnostic clues are gathered.
• Final test verifies complete functional recovery after repairs.

Concept / Approach:
Internal IC failures—like stuck outputs, excessive input leakage, or internal short/opens—are revealed when targeted diagnostic tests expose inconsistencies between expected and observed logic/function. The diagnostic phase is when you first perform these structured tests: loopback checks, stimulus-response tests (using logic pulsers), signature analysis, or boundary scans. While isolation deepens the localization, the “aha” that an IC is misbehaving typically originates during diagnostics.

Step-by-Step Solution:

Verification / Alternative check:
Use cross-substitution (swap a known-good IC), or consult datasheet truth tables during diagnostics; if the device fails the table consistently, the fault attribution occurs in that phase, reinforcing the answer.

Why Other Options Are Wrong:

Common Pitfalls:
Skipping early diagnostic basics like power rail checks; assuming the first suspect IC is bad without corroborating tests; misattributing system-level timing issues to a single chip.

Final Answer:
diagnostic