| Products > Test Equipment |
| Uni-T UT61E slowly returns to zero in all AC modes. Should I keep it or return? |
| (1/6) > >> |
| Serg65536:
It takes 2 minutes for my multimeter to drop down from several volts (or several hundreds milliamps) AC to 0. Probes are short circuited while waiting. First minute it takes to go down to 0.6mV :-DMM and second - to actually show zero reading. Is this normal operation of TrueRMS chip or should I return my new UT61E meter back? :-// |
| siealex:
Are you sure that your equipment does not induce current on the test leads? Instead of short-circuiting the test leads, remove them and short-circuit directly on the meter. Does the behavior stay the same? |
| Serg65536:
--- Quote from: siealex on August 13, 2023, 11:20:14 pm ---Are you sure that your equipment does not induce current on the test leads? Instead of short-circuiting the test leads, remove them and short-circuit directly on the meter. Does the behavior stay the same? --- End quote --- Other meters (including UT61B) drop to zero very quickly. No noise sources turned on. Alligator clip leads are good, resistance is stable 0.09Ohm. |
| Fungus:
--- Quote from: Serg65536 on August 13, 2023, 08:49:52 pm ---It takes 2 minutes for my multimeter to drop down from several volts --- End quote --- Sounds broken to me. |
| mwb1100:
Just to make sure I understand - you're putting the meter in VAC mode and shorting the leads? My limited testing shows that my "higher end" meters (87V, BM786) tend to take about 10 - 12 seconds to drop down to something around a 1mV reading, and they don't ever get to zero (or at least it takes more seconds that I was willing to wait around for - which wasn't anywhere close to 1+ minutes). Though this isn't universal - my BM235 drops to zero within a few seconds. My cheaper, no name meters tend to immediately drop to zero. If you look at the specs for VAC, I think you'll see something about readings having much less accuracy at below 10% of the range. For example, the 87V manual says, "Below 10 % of range, add 12 counts". 12 counts in the 600.0mV range of the VAC mode is 1.2mV - and that's on top of the 4 counts specified for the range in general. The specs for the BM786's 600.00mV range simply say, "Accuracy specified from 10% to 100% of range". In other words below 60mV all bets are off. The specs for the UT61E say the same thing. I suspect that you are right that the TrueRMS functionality has something to do with it, but I honestly don't know. Note that your UT61B isn't True RMS. I'm pretty sure there was a thread about this behavior in the last several months, but I couldn't find it. I was about to say that your UT61E is in good company, but then I realized that your meter starts out at several volts - mine start out at something less than 100mV, including a UT61E I have on hand. It takes my UT61E almost 10 seconds to drop to 5mV when I short the leads. How long does it take yours? I'm not sure whether or not having an open circuit reading that high is an indicator of anything. |
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