Smart SMD tester MS8911.

[MiniCheck]

I made a more advanced device for zeroing. At the same time, it can be used as a stand for tweezers.

Is that something you have to do before using them?

[iet]

Is that something you have to do before using them?

Short Circuit Zeroing: First, select the test frequency that you want to zero. Insert a short-circuit piece into the test socket,
whether using SMD test tweezers or clamps. Short-press to enter zeroing mode. The instrument will automatically
measure and execute the corresponding short circuit zeroing after identification.
This is written in the manual. You decide for yourself whether to do zeroing or not. For example, you shorted the probes 1-3 times and you have N milliohms on the display. You decide whether this error will affect the measurement results or not. If not, then there is no need to zero. If you measure low-resistance resistances and picofarads, then you must zero. In addition, I have the corresponding components soldered onto the test boards and I immediately check the zeroing result.

[iet]

To finally solve the problem of the tips, I made another pair from copper plates 1 mm thick. Everything works fine.

[iet]

Measured 8 resistors connected in series, 10 MOhm. There is nothing to check the result with. MS8911 and a multimeter - 60 MOhm.

[iet]

After carrying out all the necessary things in the milliohms range, I measured the resistance of two 1 mOhms resistors connected in parallel.

[indman]

After carrying out all the necessary things in the milliohms range, I measured the resistance of two 1 mOhms resistors connected in parallel.

[4thDoctorWhoFan]

After carrying out all the necessary things in the milliohms range, I measured the resistance of two 1 mOhms resistors connected in parallel.

Perhaps I am missing something but why do you keep posting about the Fnirsi LCR-ST1 when this thread is titled about the MS8911?
I mean, there is a dedicated Fnirst LCR-ST1 thread.

[mawyatt]

Also, how much current do these tweezers utilize thru the DUT for low Z measurements?

Best,

[iet]

Also, how much current do these tweezers utilize thru the DUT for low Z measurements?

Best,

A very interesting thing. And the most interesting thing is that this information is not available for any tweezers.
https://upload.sunsky-online.com/res/guide/TBD06051996Manual.pdf
https://mastech-group.com/resources/QSG+%E8%AA%AA%E6%98%8E%E6%9B%B8/GLO_%E8%AA%AA%E6%98%8E%E6%9B%B8/GLO%E8%AA%AA%E6%98%8E%E6%9B%B8_%20%20MS8911.pdf
https://www.lcrresearch.com/_files/ugd/97c2bb_73362b7481694861a96b1bed0670c66b.pdf

[mawyatt]

This can be measured relatively easy with a small DUT resistor, say 1 Ω. Attach a DSO across the DUT and observe the measurement waveform from the tweezer, or if a DSO isn't available use a DMM. Keep the frequency low for the DMM since they usually don't respond well at higher frequencies.

Another option if one has a DSO with 50 Ω input impedance, is use the DSO 50 Ω input Z as the DUT and simply measure such with tweezers.

Maybe some folks with these tweezers can perform this simple test and report th results, we would IF we had any tweezers, unfortunately we don't!!

Best,

[iet]

This can be measured relatively easy with a small DUT resistor, say 1 Ω.

There are different ways to check.
I got the result that interested me. To do this, I had to put my hands on it and work a little. These capabilities are embedded in these tweezers, you just have to try to implement them. Such measurements are not an end in themselves, but a way to check real parameters.
A lot of talk about the diode function.
Actually, we must not forget that the tweezers are a bridge LCR meter. The D function is additional. But it is not made like in multimeters. That is, it is not finished. FNIRSI should either finish it or remove it altogether. And instead of a diode, make a measurement of the DCR resistance. This is done in the MS8911.
And if possible, then do it like in the LCR Pro1 Plus.
In a short period of time, an analysis of the serviceability of the semiconductor junctions of the diodes and transistors is carried out for breakage, partial or complete breakdown.
After the analysis, we see the result on the display.

[iet]

In this case, ST1 indicates low resistance, which corresponds to the short state.
For the correct interpretation of the short state, it is desirable that the tweezers could indicate 10 mOhms, or even better 1 mOhms. Then it will fully display the real situation.
Here is good information.
https://www.fluke.com/en/learn/blog/digital-multimeters/how-to-test-diodes#:~:text=A%20bad%20(opened)%20diode%20does,0.4%20V)%20in%20both%20directions.

[iet]

Faulty transistor.

[iet]

In-circuit measurement of diodes.

[iet]

There was such an opportunity and I bought a used Atlas DCA55. I checked the diodes on the board again, which were checked with two tweezers.

[iet]

Diode bridge. Faulty diodes of the diode bridge.

[iet]

Some conclusions can be made. Faulty diodes and transistors can be identified with ST1 tweezers. Both those soldered from the board and those in-circuit. I would like to have the ability to measure lower resistance in this mode, as is done in Pro1 Plus in Continuity mode. The continuity measurement can be used to test fuses, connectors, switches and other components.
I measured the resistance of 0.5 mOhm again with LCR Pro1 Plus tweezers.

[iet]

New firmware V1.6.
LCR-ST1-V1.6-20241121
1.Fix the problem of invalid reset

LCR-ST1-V1.5-20240827
1. Repair the logic of automatic shutdown setting
2. Add the function of identifying the direction of diode

LCR-ST1-V1.4-20240803
1. Repair the abnormal progress of resistance measurement in some intervals

LCR-ST1-V1.3-20240725
1. Repair some problems of diodes

LCR-ST1-V1.2-20240714
1. Add the function of measuring on and off under diode
2. Add Z and X secondary parameters
3. Add data saving
https://www.fnirsi.com/pages/support-and-downloads

[iet]

Video about ST1 tweezers with new firmware V1.6 and charts comparing measurements with other devices.

[iet]

There were many discussions on the forum about problems with calibration and stability of measurements in the milliohm range of the Fnirsi ST1. It seems that this was solved in the ANENG GN702 tweezers. They entered it into the calibration menu and this can be seen in the video when measuring a 2.3 mOhms resistor. It is clearly visible that the numbers do not move for several seconds, while the resistor value is accurately measured. There is also an option to rotate the screen in the menu. If this is so, then a certain progress in measurements in this range has been achieved. Can anyone confirm or deny this?
https://www.ebay.com/itm/286214675405

[DaneLaw]

There were many discussions on the forum about problems with calibration and stability of measurements in the milliohm range of the Fnirsi ST1. It seems that this was solved in the ANENG GN702 tweezers. They entered it into the calibration menu and this can be seen in the video when measuring a 2.3 mOhms resistor. It is clearly visible that the numbers do not move for several seconds, while the resistor value is accurately measured. There is also an option to rotate the screen in the menu. If this is so, then a certain progress in measurements in this range has been achieved. Can anyone confirm or deny this?
https://www.ebay.com/itm/286214675405

Confirm what?
I doubt it went over your head (as we even talked about it #61/#63/#65) that there is another cheap LCR tweezer, and there are differences between them, even though the specs are very similar.
https://www.eevblog.com/forum/testgear/lcr-tweezer-fnirsi-st-1-versus-zoyi-md-1/msg5646681/#msg5646681

To sum up, ZOYI is usually the OEM (original equipment manufacturer) behind most of the products sold under the Aneng brand.
Essentially, ZOYI design & manufactures the products, and Aneng later gets the clearance to rebrand & label ZOYI-products under the Aneng-name for certain markets.
Very common practice in China that things get rebranded for other markets.

[iet]

Confirm what?

My question was addressed to those who already have ANENG GN702 tweezers and they can confirm what is shown in the video - stability in the milliohm range. The video shows a measurement of a 2.3 mOhms resistor.
Regarding rebranding. Thanks for the information.
Unfortunately, I missed some things. Now I have carefully reviewed your message. I have a question for you. Do ZOYI MD1 and ANENG GN702 have the same menu or are there differences?

[DaneLaw]

Confirm what?

My question was addressed to those who already have ANENG GN702 tweezers and they can confirm what is shown in the video - stability in the milliohm range. The video shows a measurement of a 2.3 mOhms resistor.
Regarding rebranding. Thanks for the information.
Unfortunately, I missed some things. Now I have carefully reviewed your message. I have a question for you. Do ZOYI MD1 and ANENG GN702 have the same menu or are there differences?

Its usually the exact same product, as it tends to be when Aneng rebadges Zoyi (Zotek) products.  https://zotektools.com/products/
Their specsheet is also close to identical, just with a tad worse tolerances on the GN702 than what ZOYI put on their MD-1.

[DaneLaw]

I haven't updated my Zoyi  MD-1 for a while and I'm certainly not on the latest, which seems to be fw 1.8 or maybe 1.9?
Just checked.. my unit is on FW1.7 so an older fw but even there, and when you are in the menu (calibrate) where you can see your resistance value... it seems to be pretty stable way down in the low single digits mΩ by just shorting the tips with some force.

Another indication that it's the same product, is the firmware.. the Aneng GN702 in the video shows firmware 1.8, and that is also the firmware posted on the Zoyi -MD-1 int-download page.

Seems pretty stable down in the decimal (0.x) mΩ values.
An example by shorting the tips. (old fw 1.7)

[iet]

Its usually the exact same product, as it tends to be when Aneng rebadges Zoyi (Zotek) products.  https://zotektools.com/products/
Their specsheet is also close to identical, just with a tad worse tolerances on the GN702 than what ZOYI put on their MD-1.

All tweezers that have recently entered the market have very similar specifications and everything is more or less clear. Here I am more interested in some things about calibration in R, C mode.
 Your tweezers at the stability point show 0.4 mOhms for about 10 sec. This is good. Is it possible to get a value of 0.0 mOhms? If so, how many seconds does this value last?