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I recommend Multimeter with limited budget
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J-R:

--- Quote from: marck120 on February 03, 2022, 12:47:10 pm ---@JR

Again I did not understand how to switch to the 600mVAC range or the 60mVAC range, do I need to disable the AUTO function and switch to manual mode ?


--- End quote ---

In case you didn't find the answer to this already, the mV ranges for AC and DC volts are at the selector position for Temp.  Once at that position, you may need to press the Select button multiple times to choose Temp, mV AC or mV DC as desired.
marck120:
@rsjsouza, @bdunham7

Thank you very much for the explanations, now I have repeated the test in AC, I have also seen the video attached. After about ten minutes with the leads in short circuit the value drops to 0000, then it oscillates between 0000 and 0001, if everything is normal I don't worry. My friend @Niwivan has a BM257s identical to mine, he contacted me after he saw my video on youtube, because he too found this "anomaly" if you can call it that.

@JR

Thanks, no I did not find the answer, I have now found the answer thanks to your explanation, mv are the millivolts, to tell the truth I have never used the millivolts measurement, no I know on what occasion I might need it.
mqsaharan:

--- Quote from: Niwivan on February 03, 2022, 04:21:52 pm ---
--- Quote from: mqsaharan on February 03, 2022, 05:03:52 am ---
--- Quote from: marck120 on February 02, 2022, 08:19:35 pm ---Hi, a few months ago I bought the Brymen 257s, I noticed an anomalous thing, short-circuiting the leads should immediately go to 0, this does not happen, do you think the multimeter has some problem ?

https://youtu.be/wX4Cy5j68Ho

--- End quote ---

There is no need to worry. Your meter is fine.
In the video you linked, the meter is in ACV function. BM257s is TrueRMS meter. It is normal behaviour for such a meter in ACV function. In DCV function, it should go to zero immediately.

--- End quote ---

I have several multimeters including the BM257S here. Actually it seems strange to me too ... In DCV it is ok and it is always 0, but by orthocircuiting the leads in ACV the BM257s still remains above 0. My other multimeters such as UT61E +, short-circuiting the leads in ACV, the display stops showing values fluctuating and everything becomes 0. They are both two TRUE-RMS multimeters ??? :-//

--- End quote ---

I do not exactly know why some meters like UT61E+ shows 0 quickly and why some other meters like BM257s takes very long to show 0 with shorted probes in ac functions. May be it is because different TRMS ICs have different settling times.
No matter the reason, it is a known fact that meters with TRMS converter usually show residual reading with the shorted probes. Some manufacturers mention that fact in their manuals. For example the following paragraph is from Fluke 289 Users Manual:

"AC Floor:
When the input leads are shorted together in the ac functions, the Meter may display a residual reading up to 200 counts. A 200 count
residual reading will cause only a 20 count change for readings at 2 % of range. Using REL to offset this reading may produce a much larger
constant error in later measurements."
marck120:

--- Quote from: mqsaharan on February 04, 2022, 02:58:54 pm ---
--- Quote from: Niwivan on February 03, 2022, 04:21:52 pm ---
--- Quote from: mqsaharan on February 03, 2022, 05:03:52 am ---
--- Quote from: marck120 on February 02, 2022, 08:19:35 pm ---Hi, a few months ago I bought the Brymen 257s, I noticed an anomalous thing, short-circuiting the leads should immediately go to 0, this does not happen, do you think the multimeter has some problem ?

https://youtu.be/wX4Cy5j68Ho

--- End quote ---

There is no need to worry. Your meter is fine.
In the video you linked, the meter is in ACV function. BM257s is TrueRMS meter. It is normal behaviour for such a meter in ACV function. In DCV function, it should go to zero immediately.

--- End quote ---

I have several multimeters including the BM257S here. Actually it seems strange to me too ... In DCV it is ok and it is always 0, but by orthocircuiting the leads in ACV the BM257s still remains above 0. My other multimeters such as UT61E +, short-circuiting the leads in ACV, the display stops showing values fluctuating and everything becomes 0. They are both two TRUE-RMS multimeters ??? :-//

--- End quote ---

I do not exactly know why some meters like UT61E+ shows 0 quickly and why some other meters like BM257s takes very long to show 0 with shorted probes in ac functions. May be it is because different TRMS ICs have different settling times.
No matter the reason, it is a known fact that meters with TRMS converter usually show residual reading with the shorted probes. Some manufacturers mention that fact in their manuals. For example the following paragraph is from Fluke 289 Users Manual:

"AC Floor:
When the input leads are shorted together in the ac functions, the Meter may display a residual reading up to 200 counts. A 200 count
residual reading will cause only a 20 count change for readings at 2 % of range. Using REL to offset this reading may produce a much larger
constant error in later measurements."

--- End quote ---

Thanks for the information, yes, as you explained to me, maybe each multimeter is calibrated differently, in some multimeters they told me that there is an internal adjustment for compensation. The user @Niwivan has made the return of the multimeter also for other reasons, let's see when the new BM257S arrives if it has the same behavior. However in the end from what I understand it is a false problem, this residual reading does not affect the measurements at all. Sorry REL what function is it ? now it escapes me.
Niwivan:

--- Quote from: mqsaharan on February 04, 2022, 02:58:54 pm ---
--- Quote from: Niwivan on February 03, 2022, 04:21:52 pm ---
--- Quote from: mqsaharan on February 03, 2022, 05:03:52 am ---
--- Quote from: marck120 on February 02, 2022, 08:19:35 pm ---Hi, a few months ago I bought the Brymen 257s, I noticed an anomalous thing, short-circuiting the leads should immediately go to 0, this does not happen, do you think the multimeter has some problem ?

https://youtu.be/wX4Cy5j68Ho

--- End quote ---

There is no need to worry. Your meter is fine.
In the video you linked, the meter is in ACV function. BM257s is TrueRMS meter. It is normal behaviour for such a meter in ACV function. In DCV function, it should go to zero immediately.

--- End quote ---

I have several multimeters including the BM257S here. Actually it seems strange to me too ... In DCV it is ok and it is always 0, but by orthocircuiting the leads in ACV the BM257s still remains above 0. My other multimeters such as UT61E +, short-circuiting the leads in ACV, the display stops showing values fluctuating and everything becomes 0. They are both two TRUE-RMS multimeters ??? :-//

--- End quote ---

I do not exactly know why some meters like UT61E+ shows 0 quickly and why some other meters like BM257s takes very long to show 0 with shorted probes in ac functions. May be it is because different TRMS ICs have different settling times.
No matter the reason, it is a known fact that meters with TRMS converter usually show residual reading with the shorted probes. Some manufacturers mention that fact in their manuals. For example the following paragraph is from Fluke 289 Users Manual:

"AC Floor:
When the input leads are shorted together in the ac functions, the Meter may display a residual reading up to 200 counts. A 200 count
residual reading will cause only a 20 count change for readings at 2 % of range. Using REL to offset this reading may produce a much larger
constant error in later measurements."

--- End quote ---

Thanks everyone for the answers!. As Mark120 said, I returned my BM257s because it also had bushing "A" badly soldered with a strong misalignment, which made it difficult to insert the probe into the hole.
As for the ongoing conversation. I also learned a new thing, which is that some TRMS multimeters takes very long to show perfectly 0, with shorted probes in AC mode.
But now I have a question. Do the residual counts on the display negatively affect AC measurements of a few mV? I tried with a loop of wire around a toroidal, and I correctly measured something like 0.7 VAC. But I have no idea about lower measurements ...

Thanks
Ivan
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