How to check a fuse in a live circuit?

If the fuse in a PCB, and the circuit is energized, how do i know if the fuse is good or blown?

I generally know that in order to check a fuse, i use the Digital Voltmeter and do continuity test.

But how about a fuse in a PCB board, how can i do that?

Update:

and i can't take the fuse out.

6 Answers

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  • Anonymous
    10 months ago

    A digital voltmeter can not conduct a continuity test.

    A digital multimeter can, if you measure resistance in a deactivated circuit.

    But to answer your question, you can measure the voltage on both sides of the fuse with respect to ground or neutral. If both measurements are the same, then the fuse is functional.

    You can also measure the voltage across the fuse. Depending on the current in the circuit, if the voltage across the fuse is approximately zero, the fuse is functional.

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  • 10 months ago

    Measure the voltage drop across the fuse. If it is very close to zero, probably working fine. If there is a big voltage drop across the fuse, likely dead.

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  • 10 months ago

    If there is voltage on the downstream side of the fuse it is good. The voltage drop across a good fuse is nearly zero.

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  • 10 months ago

    measure the voltage across the fuse, it should be close to zero. Use a DC voltmeter for most cases, unless there is power AC voltages on the board, which is not common.

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  • 10 months ago

    In a live circuit, the voltage measured at each end of a good fuse should be about the same, we're looking at a wire with a bit of resistance.

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  • 10 months ago

    No current should flow through a burnt fuse. An common digital multimeter should be able to measure the amperage. Make sure that it is zero across the ends of the fuse.

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