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I have a MAXIMUM multimeter ( https://www.canadiantire.ca/en/pdp/maximum-digital-multimeter-with-true-rms-0521898p.html ) that I've been using for about a year, mainly for automotive and hobby applications. However, yesterday I needed to measure AC voltage and consistently got a reading of 0. I tried plugging it right into a household plug and it still reads 0, though it beeps and the NCV light come son to warn me there's an electric current. It works on every other setting including DC voltage, and interestingly even works on the frequency setting. I've tested both fuses with another multimeter and they both have continuity. Is there anything I can try to fix it? I know it's not a Fluke or anything, but it's still pretty expensive and it's a shame to have such an important setting not work.

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  • \$\begingroup\$ What range we you using, and which sockets? Can you link to the manual rather than the add? \$\endgroup\$
    – Transistor
    Aug 15, 2020 at 22:44
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    \$\begingroup\$ Canadian Tire is actually pretty good about replacing defective test equipment. It is worth asking them. \$\endgroup\$ Aug 15, 2020 at 22:58
  • \$\begingroup\$ funny thing ... i have a meter just like it, but differently colored ... brand name Magnum \$\endgroup\$
    – jsotola
    Aug 16, 2020 at 0:26
  • \$\begingroup\$ @DwayneReid It's about a year old, so I don't know if I'll have much luck, but I'll try first and if they won't take it back, I'll try following Barry's answer. \$\endgroup\$
    – John Arg
    Aug 16, 2020 at 17:13
  • \$\begingroup\$ @jsotola I'm not surprised... they're probably all made in the same factory and then different brands slap their own logo onto them. \$\endgroup\$
    – John Arg
    Aug 16, 2020 at 17:13

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The fuses are only used for the current ranges and have no bearing for AC voltage measurements. Since this is a true RMS voltmeter, there is undoubtedly an IC inside which does the conversion from input AC voltage to a DC voltage proportional to the RMS value of the input. Since the meter works on frequency, the input AC circuits are probably OK. Since the meter works on DC, the DC measurement circuitry is also OK. Since the latter is also used for AC measurements, by measuring the output of the RMS converter IC, the most likely culprit is that IC. You need to open up the meter and first look for obvious problems like burnt components or loose wires. Then try to identify the RMS chip. If you can get another one at a reasonable price, you can try replacing it. You could also try contacting the manufacturer of your meter to see if they could offer any assistance.

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