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How to discharge and test a capacitor safely

Capacitors can hold a dangerous charge after power is removed. Kill power, verify 0 V, discharge through a resistor (not a screwdriver), confirm 0 V, then test capacitance against the label. Microwave high-voltage capacitors carry extra risk and need their own procedure.

Cross-checked ~15 min moderateBrands: All

Before you start

Treat every capacitor as charged until you have measured 0 V across it
Never short terminals with a screwdriver: arcing damages parts and can injure
Microwave HV capacitors: follow the microwave-specific procedure; caution

Diagnostic steps

Unlock all 4 steps with expected values

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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