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I have a cheap multimeter that used to work fine but now it has negative readings -- even when the leads aren't connected. I changed the battery, looked for a blown fuse but no luck.

Any idea what's going on? Is it toast? It's a GB Instruments GDT-11.

(Picture added)

Multimeter always shows negative

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  • \$\begingroup\$ Did you try reversing the leads? \$\endgroup\$
    – Sherby
    Oct 3, 2013 at 3:56
  • \$\begingroup\$ Yes, tried switching but it's negative. Note -- it does fluctuate when I try to test something, but remains negative or definitely off even if it is positive. \$\endgroup\$
    – Voodoo
    Oct 3, 2013 at 4:02
  • \$\begingroup\$ Same result on all the ranges, or just on "2000 m"? \$\endgroup\$
    – The Photon
    Oct 3, 2013 at 4:05
  • \$\begingroup\$ Return it for an exchange? Also check for trim pots. \$\endgroup\$
    – Passerby
    Oct 3, 2013 at 4:16
  • \$\begingroup\$ Negative reading depends on range - goes downfor a smaller range. @passerby - what are trim pots? \$\endgroup\$
    – Voodoo
    Oct 3, 2013 at 5:51

1 Answer 1

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Replace multimeter with a reputable brand. Depending upon your application and needs, you can either go for a cheap multimeter or an expensive one like Fluke, Agilent, etc.

Occasional and hobby use: Buy a cheap one from RadioShack. Further, if not measuring high voltage, get one from Harbor Freight for < $6.

Harbor Freight Multimeter RadioShack Multimeter

Professional use: Buy your equipment from Fluke, Agilent, etc. Equipment from reputable manufacturers will give you peace of mind, ROI on the equipment, reduced liability if you have employees, accurate measurement, etc.

Fluke1 Fluke2 Agilent

Beware, do not trust a cheap multimeter for high voltage measurements. Review and verify the CAT rating on the multimeter if you frequently measure high voltages.

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  • \$\begingroup\$ Nice vid that discusses the difference between multimeters and what to watch out for. eevblog.com/2010/04/14/… \$\endgroup\$
    – jippie
    Oct 3, 2013 at 5:36
  • \$\begingroup\$ You forgot speed - my Agilent arrives at a stable reading as soon as you touch the probe to the board, whereas the cheap ones wobble around for a second or so. I'm all for the <$5 ones bought in bulk and scattered around the lab/workshop/toolbox (same with tape measures) for those moments when you just need to measure something quickly, but if you need to really believe the result you gotta spend some cash. \$\endgroup\$
    – John U
    Oct 3, 2013 at 8:13
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    \$\begingroup\$ It may be worth mentioning that, although good multimeters cost a lot more than the cheap one the OP has, you can buy good-condition used Flukes on eBay for reasonable prices. Even an ancient $40 Fluke-25 will do all that the OP's meter does, plus auto-ranging, 0.1% basic DCV accuracy and much much much better safety - just make sure the LCD display is OK before buying. With patience you can pick up something like a good-condition Fluke 87-III for maybe $120 (probably less in the USA). \$\endgroup\$
    – RedGrittyBrick
    Oct 3, 2013 at 10:42

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