Field troubleshooting technique: can a standard ohmmeter or the “diode test” function on a digital multimeter be used to test a diode’s forward and reverse behavior for basic health checks?

Introduction / Context:
Technicians routinely perform quick checks on diodes using handheld meters. While such tests are not full characterization, they can quickly reveal open or shorted devices and gross leakage issues.

Given Data / Assumptions:

• DMM has a diode-test mode or resistance mode.
• Device under test is isolated from the circuit or at least one lead is lifted.
• Ambient temperature conditions; no high-power stress during the test.

Concept / Approach:
In diode mode, the meter sources a small current and displays forward voltage (typically around 0.2–0.3 V for Schottky, 0.6–0.8 V for silicon). In reverse polarity, the reading should show open circuit (often “OL”). In resistance mode, the forward direction yields a lower resistance than reverse. These checks confirm basic junction integrity.

Step-by-Step Solution:

Verification / Alternative check:
Compare measured forward drop to device datasheet typical values at similar current; a large deviation can indicate damage or a wrong part.

Why Other Options Are Wrong:
Incorrect: denies a standard practice.

Only Schottky or only high-current diodes: the method works for most diode types (rectifier, small-signal, LED with care), acknowledging that LEDs show higher forward drops.

Common Pitfalls:
Testing in-circuit and misreading due to parallel paths; expecting exact datasheet forward voltages at the meter’s tiny test current; forgetting polarity.

Final Answer:
Correct