DMMCheck Plus Multimeter Reference(and other References) - Experiences..

[bdunham7]

At the moment my SDS2504HD measure the same signal - without "deforming"...
Must investigate this.

The SDS1104X-E was not set to AC coupling, was it?

I think this is a known issue with the scope at low frequencies.

Here's 100Hz 10V_p-p from SDG2042X direct to SDS 1104X-E with settings as shown.

[Domitronic]

I think this is a known issue with the scope at low frequencies.

Yes, at least my SDS1104X-E has the same issue:

https://www.eevblog.com/forum/testgear/siglent-sds1204x-e-released-for-domestic-markets-in-china/msg4433131/#msg4433131

Others reported the same in this thread.

[Martin72]

Yepp, it must be an issue - connect the signal directly without a probe to the scope, no changes.
Hmm..Not so nice for SDS1104X-E owner.

[Veteran68]

I'm shocked, SHOCKED!, I tell you! 

I knew when I got it that there was no way they were typing up, printing, and cutting out each of these for each unit. The handwritten ones are much more believable.

The date on it should be a giveaway. When did you buy yours?

Had to search email history to figure out where and when I bought it.

EBay, Feb 2020. So yeah it came with 5yo cal sheet from some other device (if not entirely made up numbers to begin with).

I had bought a few different varieties of these cheap ones, like the other ones pictured in this thread, but this one was an odd duck with its battery requirement so after I was done playing with it, it went into a drawer and was never used again.

Since then I bought a LB02A process calibrator which is handier and more fun to use, and is really all the reference I need for my hobby purposes.

[Martin72]

Now the SDS2504X-HD...
You musn´t buy this to get the nice histograms, you could have them with a unlikely more cheaper SDS2000X-Plus.
But the accourate DVM, you get it only with the 12bit model.

[KungFuJosh]

I love the details on the HD's measurements.

[Martin72]

Meanwhile I remember of my third LCR meter I got, a mastech MS8911 smart smd tester with testfrequencies up to 10khz..Must check it too.

Did it, it´s not too bad...
Testfrequency 10khz..(reference)
1050 µH (1032µH)
104.8µH (104.3µH)
10.5µH (10.52µH)
1µH (1.061µH)

1.017nF (1.019nF)
10.14nF (10.16nF)
102.3nF (102.5nF)
1.013µF (1.001 µF)

DCR

100.0 Ohm (100.058)
0.999 kOhm (0.9994)
9.999 kOhm (9.9995)
100.0 kOhm (100.017)

[tatel]

Now that I got this thing and almost half a dozen multimeters, I reckon it's time for me to work out some spradsheets. So here it's my first try at it. All I can say it seems to work. But, since I really don't know what I'm doing, please feel free to criticize it sharply and maybe even use it

[Martin72]

Hi,
I have taken the liberty of making it more visible, your notes on the sheet as a quote:

Notes: The sticker in DMMCheck+’s back says AC Amps uncertainty is 0.2% but in the manual I see 0.5%. Am I high?
The sticker also says L, C are calibrated to 0.05% but nothing is said about it in the manual.
No TC specified for many DMMCheck+ measurements. Uncertainty min/max is calculated first. Then, available TC is added/substracted to uncertainty.
869s TC isn’t calculated if T is in the 18-28 Cº ranges. Otherwise it’s added/substracted to uncertainty.
869s’ DC V in dual mode reads 5.0011V. Single mode reads 5.0000 and 5.00006 V. So dual mode = less precision?
No Hz reading when measuring AcmA (0.000), however Hz reading is OK when reading ACV

Here my BM869s results:
https://www.eevblog.com/forum/testgear/dmmcheck-plus-multimeter-calibration-reference-experiences/msg4950205/#msg4950205

Interesting thing with the dual display, must check this too.
L/C values: Indeed it´s only measured with a device which got 0.05% basic precision.

[Martin72]

Interesting thing with the dual display, must check this too.

Indeed, according to the manual single mode display is only avaible in DCV mode, also the 500000 counts.
Only when DCV, nothing else.

[tatel]

Interesting thing with the dual display, must check this too.

Indeed, according to the manual single mode display is only avaible in DCV mode, also the 500000 counts.
Only when DCV, nothing else.

What looks strange to me is that 11 counts difference between DCV in dual mode vs single mode in 50000 counts mode. I mean, shouldn't be the involved guts be almost exactly the same? turning on some more led segments is enough to get a 0.02% difference?

Not that I care so much about it, but I was expecting it to read exactly the same in both display modes.

[J-R]

Frequency measurements are possible in ACmA mode on the BM869s, but it may not display at very low currents.

Also, you can only calibrate DCV and ACV ranges, not any of the combined modes.  The readings in combined mode can be up to 80 counts off.

I didn't have time to dig further to see what is causing the error.  I think I will calibrate the ACV mode and see if that impacts it.

[bdunham7]

Not that I care so much about it, but I was expecting it to read exactly the same in both display modes.

On most meters with dual-display modes they still only have one ADC so they can't measure simultaneously.  When they switch back and forth between modes, the meter may not be able to settle quite as fully as it would in the single display mode.  This slight (or in some cases not-so-slight) degradation happens with almost all meters with these dual modes. 

[tatel]

Frequency measurements are possible in ACmA mode on the BM869s, but it may not display at very low currents.

Also, you can only calibrate DCV and ACV ranges, not any of the combined modes.  The readings in combined mode can be up to 80 counts off.

I didn't have time to dig further to see what is causing the error.  I think I will calibrate the ACV mode and see if that impacts it.

Thank you. Seller has about the same opinion. I measured ACV on the "I" outputs of DMMCheck, got about 0.5V. Then I measured ACmA on the "V" terminals, so 5V. I got a good 100 Hz and 10 kHz readings at about 28mA.

So it turns out this DMM works fine and DMMCheck+ output is somehow too low on the "I" terminals for it to read Hz on the mA mode.

[Martin72]

Got an answer from welectron about additional calibration of the DMMCheck plus.
Will cost about 85€, pro would be a "real" calibration according to ISO standards, including a report - I already knew it from my brymen.
Con: 85€...
Will sleep about it, then decide.

[KungFuJosh]

Got an answer from welectron about additional calibration of the DMMCheck plus.
Will cost about 85€, pro would be a "real" calibration according to ISO standards, including a report - I already knew it from my brymen.
Con: 85€...
Will sleep about it, then decide.

For 25€ I can scribble out the AD584 and doodle in DMMCheckPlus on this paper, and it will be just as useful. 😉

[Martin72]

Such "scraps" of paper do not interest me at all, because completely worthless.
There is even the option to have the checker calibrated according to DakkS...
But then it becomes three-digit in terms of price.
That does not have to be, for the hobby.

[KungFuJosh]

That's my point. 😉

Since this is just for hobby use, and it already has some level of calibration, do you really benefit from spending more money on calibration? I'd save that cash and spend more money on their new improved model. 😉😉

[Martin72]

When it comes with the same sheet of paper it is as useful as the "old" one..
And as long as they would use the same reference IC nothing great will change, maybe the stability but this you can check with a period calibration, regardless if new or old version.

do you really benefit from spending more money on calibration?

When I want to know if it´s "true", it should be worth the money.
My skepticism started when I realized that the components on the L/C board are not high accuracy types, but only those that were measured with their LCR meters.
Then most of the values are rounded.
It may be that I am "damaged" by my profession in this respect, but if it is advertised that it should be a device for the calibration of other devices, then it should also be documented extensively.

[KungFuJosh]

It may be that I am "damaged" by my profession in this respect, but if it is advertised that it should be a device for the calibration of other devices, then it should also be documented extensively.

I would return it if you don't feel it's reliable or accurate enough. For what you're investing in it plus calibration, you could build your own test board with whatever components & accuracy level you want, and then send the board you made to be calibrated. IMHO that would be a better reference.

For me, that would be more entertaining, and less expensive. Hmmm. Maybe I'll make a test PCB for all the SMD stuff I got for calibration. 🤔

Edit: aaaand I already drew a schematic for it. Super simple for a passive test board.

[J-R]

Ran some LC tests:

[Martin72]

Ah, the good old DE5000 - Most underrated lcr-meter ever..

[mawyatt]

For me, that would be more entertaining, and less expensive. Hmmm. Maybe I'll make a test PCB for all the SMD stuff I got for calibration. 🤔

Edit: aaaand I already drew a schematic for it. Super simple for a passive test board.

Something like these?

Which are obviously directed towards bench type DMMs with the 4 banana plugs directly on the PCBs.

Edit: Second image came in upside down, so it's measuring Mhos not Ohms 

Best,

[mawyatt]

Here you can see the test fixture with another DMM measuring its temperature, altho we haven't found this feature very useful but included such just in case.

Best

[Martin72]

Maybe I'll make a test PCB for all the SMD stuff I got for calibration. 🤔

Remember my post ?

https://www.eevblog.com/forum/testgear/th2830-vs-th2832/msg4957831/#msg4957831