They look "goldish" the pcb also looks like ENIG finish. All looks good, so I have no idea why it happens.
Hi joeqsmith,
yes, I can handle line voltages and do so regularly.
Do you think it's related to spikes on the mains? I usually use a 0-300V 6A insulating transformer for tests like this, but if you think it makes sense I can test directly on mains but have only 230V available then. So your request would be >50VA for >6h logging to SD-card? Resistive load would be fine (they are more quiet)?
I will run it over night and hope it doesn't burn down the house. :-)
Just tell me if with or without the transformer.
I was checking the power using an arb, amplifier and transformer coupled. It seems like it was limited to 50V when I started to turn it up. You don't need a lot of current. Obviously the meter has no problems reading just voltage. It was tied to the power measurement.
They look "goldish" the pcb also looks like ENIG finish. All looks good, so I have no idea why it happens.
May be they don't reach well the pcb?
In lowZ mode the meter only starts to display a value >0 when the voltage rises to around 11.5V. When the voltage is lowered from 12V it works down to around 3V. If this is expected behaviour, it should be documented in the manual.
In lowZ mode the meter only starts to display a value >0 when the voltage rises to around 11.5V. When the voltage is lowered from 12V it works down to around 3V. If this is expected behaviour, it should be documented in the manual.I haven't had a meter with a Low Z mode so I am not familiar with how it is meant to work. It seems to be trying to autodetect whether the input is AC or DC and it needs at least 12V to do this. It has no ranges so I assume the 550V range is fixed. The Low Z input resistance looks to be about 2.7K ohms which would dissipate 112W at 550V!
To limit dissipation to, say, 5W, then you are limited to around 110V maximum. At 240V, the dissipation would be 21W which is a lot of heat to be contained inside the meter. You could do a quick measurement, but a long term measurement would be really cooking the insides of the meter.
I think I will be replacing the 2.7K resistors with something much larger. 27K or higher. This seems like a dangerous feature as it is right now. Like the VA mode, very underveloped as you can see from the lack of documentation and specifications in the manual.
In lowZ mode the meter only starts to display a value >0 when the voltage rises to around 11.5V. When the voltage is lowered from 12V it works down to around 3V. If this is expected behaviour, it should be documented in the manual.I haven't had a meter with a Low Z mode so I am not familiar with how it is meant to work. It seems to be trying to autodetect whether the input is AC or DC and it needs at least 12V to do this. It has no ranges so I assume the 550V range is fixed. The Low Z input resistance looks to be about 2.7K ohms which would dissipate 112W at 550V!
To limit dissipation to, say, 5W, then you are limited to around 110V maximum. At 240V, the dissipation would be 21W which is a lot of heat to be contained inside the meter. You could do a quick measurement, but a long term measurement would be really cooking the insides of the meter.
I think I will be replacing the 2.7K resistors with something much larger. 27K or higher. This seems like a dangerous feature as it is right now. Like the VA mode, very underveloped as you can see from the lack of documentation and specifications in the manual.
My Aglient U1232A has an impedance of 3.6kOhm on its LowZ mode. I think 2.7kOhm on the 121GW is fine.
In lowZ mode the meter only starts to display a value >0 when the voltage rises to around 11.5V. When the voltage is lowered from 12V it works down to around 3V. If this is expected behaviour, it should be documented in the manual.I haven't had a meter with a Low Z mode so I am not familiar with how it is meant to work. It seems to be trying to autodetect whether the input is AC or DC and it needs at least 12V to do this. It has no ranges so I assume the 550V range is fixed. The Low Z input resistance looks to be about 2.7K ohms which would dissipate 112W at 550V!
I think I will be replacing the 2.7K resistors with something much larger. 27K or higher. This seems like a dangerous feature as it is right now. Like the VA mode, very underveloped as you can see from the lack of documentation and specifications in the manual.
In lowZ mode the meter only starts to display a value >0 when the voltage rises to around 11.5V. When the voltage is lowered from 12V it works down to around 3V. If this is expected behaviour, it should be documented in the manual.I haven't had a meter with a Low Z mode so I am not familiar with how it is meant to work. It seems to be trying to autodetect whether the input is AC or DC and it needs at least 12V to do this. It has no ranges so I assume the 550V range is fixed. The Low Z input resistance looks to be about 2.7K ohms which would dissipate 112W at 550V!
No! That's not how this meter or any other Low-Z meter works.
The "resistor" is actually a PTC themristor, it's resistance increases when it heats up.
NOTE: Can we please limit this thread to reporting and confirmation of bugs and issues, any discussions should be on the discussion thread.
Thanks.
I haven't had a meter with a Low Z mode so I am not familiar with how it is meant to work. It seems to be trying to autodetect whether the input is AC or DC and it needs at least 12V to do this. It has no ranges so I assume the 550V range is fixed. The Low Z input resistance looks to be about 2.7K ohms which would dissipate 112W at 550V!
To limit dissipation to, say, 5W, then you are limited to around 110V maximum. At 240V, the dissipation would be 21W which is a lot of heat to be contained inside the meter. You could do a quick measurement, but a long term measurement would be really cooking the insides of the meter.
I think I will be replacing the 2.7K resistors with something much larger. 27K or higher. This seems like a dangerous feature as it is right now. Like the VA mode, very underveloped as you can see from the lack of documentation and specifications in the manual.
Probably some thermistor or similar.
Instruction Sheet for Fluke SV225 says:
Specifications
Voltages up to 1000 volts continuous can be safely applied to
the Adapter without damage.
Operation Temperature
-20 °C to +55 °C (-40 °F to 131 °F)
Altitude
2,000 Meters Operating
Humidity
90 % at 0 to 35 °C (32 °F to 95 °F), 70 % at 35 to 55 °C
(95 °F to 131 °F)
Nominal Resistance
3,000 ? @ 25 °C (77 °F)
I would think it uses a PTC thermistor, so it draws a semi constant power over the voltage range. You find a similar one in the cheap voltstick devices.
NOTE: Can we please limit this thread to reporting and confirmation of bugs and issues, any discussions should be on the discussion thread.
Thanks.I think we have been doing that. If I crossed a line by not understanding the undocumented low Z mode, I apologize.
Keep us posted on the data logging.
mm@ovid:~/121gw$ head -10 18011200.CSV ; echo "[...]" ; tail -10 18011200.CSV
START,2018/01/12,01:48:47,
ID,170800000,
INTERVAL,000,sec,
,MAIN,,,SUB-1,,,SUB-2,,,Remark,
No. ,Func. ,Value,Unit,Func. ,Value,Unit,Func. ,Value,Unit,
1,DCVA,00000.0,mVA,DCV,00.0001,V,DCA,-0001.41,mA,,
2,DCVA,00000.0,mVA,DCV,00.0001,V,DCA,-0001.41,mA,,
3,DCVA,00000.0,mVA,DCV,00.0001,V,DCA,-0001.41,mA,,
4,DCVA,00000.0,mVA,DCV,00.0001,V,DCA,-0001.41,mA,,
5,DCVA,00000.0,mVA,DCV,00.0001,V,DCA,-0001.41,mA,,
[...]
130656,DCVA,01292.9,mVA,DCV,03.2999,V,DCA,0391.83,mA,,
130657,DCVA,01292.9,mVA,DCV,03.2999,V,DCA,0391.83,mA,,
130658,DCVA,01292.9,mVA,DCV,03.2999,V,DCA,0391.81,mA,,
130659,DCVA,01292.9,mVA,DCV,03.2999,V,DCA,0391.81,mA,,
130660,DCVA,01292.9,mVA,DCV,03.2999,V,DCA,0391.81,mA,,
130661,DCVA,01292.9,mVA,DCV,03.2999,V,DCA,0391.81,mA,,
130662,DCVA,01292.9,mVA,DCV,03.2999,V,DCA,0391.81,mA,,
MAX,49,DCVA,01294.1,mVA,
MIN,1,DCVA,00000.0,mVA,
When I was reviewing the 121GW meter, almost every time I turn the knob from OFF to Low-Z, the back-light flickers.
The back-light going on for about 0.1 sec seems to consume battery consumtion every time start using the meter.
I did run VA logging for about 9h over night.
It produced a logfile with 130662 entries, which is about 4 lines per second.
So this seems fine.
Should I try something else?
What's the open circuit HV diode test putting out now?
What's the open circuit HV diode test putting out now?17.332V