Products > Test Equipment
EEVblog 121GW Multimeter Issues
Kleinstein:
The meter should not cool down form turning on blue-tooth. If at all the temperature reading may change, by some interference.
The temperature reading is likely not that accurate anyway, so I would not worry much about this part. The question is if it effects other measurements too ?
Kean:
--- Quote from: ShortCircuit on October 16, 2021, 09:00:09 pm ---Did anyone else notice that turning the bluetooth on causes the meter to cool by more than half a degree C and turning it back off causes it to heat back up to previous half a degree higher temperature?
--- End quote ---
I can confirm this happens on my 121GW. Drops about 0.6C within a few seconds when BT is turned on, and rises again very quickly after it is turned off.
The thermistor NTC1 which I presume is used for temperature sensing is at top right of the PCB (looking from the back) and BT module at top left.
I hooked up some fine wires so I could monitor B+, VDD (3.6V), and VDD_P (3.3V) with the case closed. The thermistor is part of a voltage divider on VDD.
VDD and VDD_P do not really change when BT is enabled, but I do see a small drop on B+ due to the extra load.
VREF+ on the STM32 connects to VDDA which connects to VDD_P. No idea... maybe a firmware issue with code trying to correct for something no longer relevant?
Kean:
--- Quote from: Kleinstein on October 18, 2021, 08:55:41 am ---The temperature reading is likely not that accurate anyway, so I would not worry much about this part. The question is if it effects other measurements too ?
--- End quote ---
It is used for CJC with the thermocouple, so thermocouple readings also drop by the same amount.
Weird that they put the thermistor so far away from the input jacks when it is used for CJC.
CompNut:
I just received my meter today from Amazon. The app connects to the meter but does not display anything. I tried the Meteor app and that works. I am using an LG V60 with Android 10.
vulpes:
Is this meter worth getting now? Have the firmware issues been fixed after some years in production?
I'm torn between this and Brymen 869, but I'd appreciate a smaller size and Bluetooth on GW121.
Thanks!
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