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| 121GW LowZ mode not showing AC or DC indication on Display |
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| 66seb:
Hi All. Have a 121GW for many years (got it when it was on kickstarter in Dec'17 = early supporter) but something's always annoyed me: When using LowZ the voltage reading doesn't show either "AC" nor "DC" indication on the LCD, I think it's an oversight and should be patched in a firmware update (I've now updated to v2.05, still the same). I understand, from the manual that the meter's exclusively performing an AC measurement of the voltage in this mode, so why not show "AC" on the display? :-// Kind Regards. |
| thm_w:
There is a "LowZ" indicator on the LCD, but, Fluke will show both the LoZ and AC indicators as you suggested. edit: the LowZ mode will detect if its AC or DC then display the corresponding indicator. Its not explained in the manual. I guess it could initially say "AC+DC" but I don't think its really an issue. |
| 66seb:
Dear tthm_w, Thank you for your reply, you're right, it detects both and indicates "AC" or "DC"................................ eventually. So I can use it to monitor and speed up the discharge to a safe level of DC circuits so I don't get a shock when rushing fault-finding, so I am relieved 'cos I expected this feature when I bought it, DC Low Z's super useful. The time the meter takes to read is excruciating, 2 seconds at least, and won't work much under 12V, when a 12v Car or SLA battery is a bit flat it sees nothing, LowZ's no good for automotive and leisure/camper use (I didn't expect it to be really, LowZ's primarily for 50+ volts applications I think, please correct me). 2 years ago whilst faultfinding van electric windows for a mate, when pressing the window buttons it wouldn't read anything in this mode, now I know why, either not enough volts or too short a press. Ultimately I wanna know the limitations of each feature/mode so I do not make bad measurements and waste time chasing red herrings. The 12V limitation is explained in the manual, OK, but only mentions it does AC so I though LowZ on this meter was limited to AC exclusively. But 2 or 3 seconds :wtf: Whilst the firmware is fine then, the manual is where an overdue revision is required. 6 years after the meter came out, the feature set/ manual is still not clear, I confess that I have come to not trust this instrument. Fluke's the way. |
| J-R:
Personally I would not use the 121GW Low Z mode so much. First, if there is a potential for dangerous voltages, then relying on it before touching things seems unsafe. What if you drain the circuit with the Low Z mode, but then it charges back up over a few seconds after removing the DMM? Next, Low Z is 1K Ohms + 1.2K Ohms PTC. Fluke's SV225 Stray Voltage Eliminator is similar, around 3K Ohms total. That could be a lot of load to be placing on random circuits in my opinion. So I use the regular AC, DC or AC+DC modes primarily. Then switch to Low Z mode in the specific use cases that require it. The 121GW is regarded as being on the slow side, but in all fairness quite a few DMMs that I have are also slow in "Auto" modes since they need to switch back and forth between AC and DC before deciding which is more prominent. |
| thm_w:
--- Quote from: J-R on November 24, 2023, 04:47:00 am ---Personally I would not use the 121GW Low Z mode so much. First, if there is a potential for dangerous voltages, then relying on it before touching things seems unsafe. What if you drain the circuit with the Low Z mode, but then it charges back up over a few seconds after removing the DMM? --- End quote --- This is the case with anything that has LowZ and isn't really a valid concern IMO. You'd use it to discharge a cap on a board thats not plugged in. Or to eliminate ghost voltages from wiring, the voltage may rise again but the current would be very low. --- Quote ---Next, Low Z is 1K Ohms + 1.2K Ohms PTC. Fluke's SV225 Stray Voltage Eliminator is similar, around 3K Ohms total. That could be a lot of load to be placing on random circuits in my opinion. So I use the regular AC, DC or AC+DC modes primarily. Then switch to Low Z mode in the specific use cases that require it. The 121GW is regarded as being on the slow side, but in all fairness quite a few DMMs that I have are also slow in "Auto" modes since they need to switch back and forth between AC and DC before deciding which is more prominent. --- End quote --- Yes you only use it when needed not as the default measurement method. 121GW is very slow, I'd rather use a $10 cheapy for frequent everyday tasks (continuity, basic voltage testing, etc.). Most high res/multifunction meters are slow though. |
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