PCB fault-finding: which instrument best helps trace current paths to locate a shorted track or shorted component on a printed circuit board?

Introduction / Context:
Short circuits on printed circuit boards can be difficult to localize by visual inspection alone. Specialized tools can help follow actual current flow to the precise fault location, reducing rework time.

Given Data / Assumptions:

• There is an unintended short between nodes or rails.
• We need to follow the path of highest current draw.
• Board is powered in a controlled, current-limited way during tracing.

Concept / Approach:
A current tracer (paired with an injection source or current probe) senses magnetic fields produced by current and lets the technician follow the flow along traces. The signal peaks near the short location, enabling pinpoint diagnosis even in multilayer designs.

Step-by-Step Solution:
Power the board with a safe, current-limited supply.Use the current tracer probe along the suspect net, observing the indicator strength.Follow increasing signal intensity until the maximum is found—this is the shorted region.

Verification / Alternative check:
Confirm by isolating components, thermal imaging (hot-spot), or resistance/voltage drop measurements across small copper lengths to corroborate the tracer’s indication.

Why Other Options Are Wrong:

• Multimeter: Useful for resistance checks but poor at spatial localization of shorts on complex layouts.
• Logic pulser: Injects logic pulses for functional testing, not for tracing DC shorts.
• Oscilloscope: Excellent for waveforms but cannot “sniff” current paths over copper planes.

Common Pitfalls:

• Not limiting current during tracing may overheat components.
• Misinterpreting ground-return currents; ensure proper reference and path selection.

Final Answer:
current tracer