Finding a short circuit with a multimeter
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CircuitScope · Added 05 Oct 2026 · 2 views
Continuity, voltage-injection and thermal tricks to locate a dead short.
A shorted rail is one of the most common causes of a dead board. Here's how to pin it down.
- Continuity / low-ohms: with the board off, probe the shorted rail to ground. Move along the rail — the reading drops toward zero as you get closer to the short.
- Voltage injection: feed a low, current-limited voltage (e.g. 1–3 V, ~1 A) into the rail and feel or measure for the component that heats up.
- Freeze spray / thermal camera: the shorted part warms first — a thermal camera or a dab of isopropyl (which evaporates fastest over the hot spot) reveals it.
- Once found, remove the suspect cap/IC and re-test the rail to confirm the short is gone.