Finding a short to ground on any board
A device-agnostic method for localising shorts with diode mode, current limiting and thermal imaging.
Safety first — High risk
Stored capacitor energy, mains-adjacent circuits or hot air work. Discharge, insulate and work with eye protection.
Tools required
- · Multimeter
- · Bench PSU
- · Thermal camera
- · Freeze spray
- · Microscope
Parts required
- · Replacement capacitors
- · Flux
- · Braid
Diagnostic notes
Always write down the diode-mode value of the healthy rails on a known-good board. Comparative measurement finds faults far faster than absolute thresholds.
Problem mapped: Board has a short to ground · component-level severity high
Repair steps
- 1
Map the rails
List the major rails and their expected diode-mode values from the boardview.
Step photo placeholderMap the rails — illustrative repair step photo placeholder - 2
Find the offending rail
Measure each rail to ground and flag anything dramatically lower than expected.
Step photo placeholderFind the offending rail — illustrative repair step photo placeholder - 3
Current-limit the rail
Inject the rail voltage from a bench supply with a conservative current limit.
Step photo placeholderCurrent-limit the rail — illustrative repair step photo placeholder Warning: Injecting the wrong voltage destroys boards. Confirm the rail name twice before you connect.
- 4
Localise the heat
Use a thermal camera or freeze spray to find the component absorbing the current.
Step photo placeholderLocalise the heat — illustrative repair step photo placeholder - 5
Confirm and replace
Lift the part, re-measure, and replace with a matched component.
Step photo placeholderConfirm and replace — illustrative repair step photo placeholder Tip: If the rail is still short after removal, the fault is downstream — keep going, don't shotgun parts.
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