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I have a quite new Keysight U1242C with its own test lead set. When I put the multimeter in "continuity test" mode, it should "beep" when the probes touches together.

Instead, it happens it detects a short-circuit (it emits the sound and shows about 0 ohm) even if the probes are separated. Moving the probe's wires the detection changes continuously, but I really cannot understand how this may happens.

If the probes were connected together and the wires had a bad contact, it makes sense. But the other way around leave me puzzled. How can two non-touching wires lead to a short-circuit?

Should I change the probes or the multimeter? Unfortunately I don't have another set of probes, I need to buy another pair to make the test. So, before, I'm asking here if anyone has an idea of what's going on.

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  • \$\begingroup\$ Do it still show this behaviour if you unplug the test leads from the multimeter? \$\endgroup\$
    – Graham Nye
    Commented Sep 21 at 11:27
  • \$\begingroup\$ @GrahamNye no, it happens only with the test leads connected and moving them \$\endgroup\$
    – Mark
    Commented Sep 21 at 11:30

2 Answers 2

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This product seems to autorange and have a continuity threshold which varies with range, which seems like a really annoying "feature" to me, but this is what the manual says:

enter image description here

Anyway, if it's doing that, then it appears the meter is misbehaving. Assuming you've already checked that the battery is fresh, you might want to ask about a a warranty repair. If something bad happened to the meter (like maybe someone got it wet) that will probably be denied.

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  • \$\begingroup\$ "which seems like a really annoying "feature" to me" The meter has a range button so presumably you can manually select a resistance range and hence a continuity threshold. (But yes.) \$\endgroup\$
    – Graham Nye
    Commented Sep 21 at 11:37
  • \$\begingroup\$ @GrahamNye Yes, I expect so. To save one switch position they force the user to switch to manual range and then back again for normal use. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Sep 21 at 11:43
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Your multimeter has a low impedance mode (to avoid stray coupled voltages when making AC measurements) which puts a 1.8 kΩ resistance between the input terminals. Do you need to switch this off? (I would have expected it to only be activated during AC voltage measurements but I don't have this model to try out.)

The manual (registration required) doesn't make this clear.

If that's not it, better quality meters including this model, have circuits to detect when test leads are plugged into the sockets. (This provides a visual and audible warning if you've plugged into the wrong socket for the measurement you're making.) It's possible that this detection has gone wrong and is creating the symptoms you're seeing. Do the readings change when you move the leads in a way that pulls on the meter input sockets? If that's the case it will be a warranty repair.

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  • \$\begingroup\$ The Quick Start Guide (page 11) says that it has "input warning" - it shows on the display, not the sockets. \$\endgroup\$
    – Andrew Morton
    Commented Sep 21 at 17:41

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