Debranded Micsig handheld scope on sale on eBay

[elebot]

Apparently Micsig is selling their MS220T scopes with some multimeter issues debranded on eBay - http://www.ebay.com/itm/322153406489 (advertised as fully functional, only with disabled multimeter funtion).
It is my guess that it is MS220t as the features/params match but have not seen internals of the "real" MS220t.
The price seemed OK to me (even with the shipping, duties and taxes) so now I have my first handheld scope.

In the spirit of this forum I had to open it and here are some pictures of the internals.

As you can see there are quite some differences to the isolated version Dave has reviewed.


The multimeter is disabled in HW by disconnecting the red plus socket and in SW by (at least) disabling the "Meter". Also the square wave test signal for probe compensation is not available as it is also generated by the multimeter.

You can fully control the scope via USB but unfortunately the SW is for 32b Windows only (Win 7 and up), no 64b version :-(


Have not checked all the features/params but so far I am quite happy with the purchase.

[Assafl]

Is it not isolated channels? even when using a battery?

I like my Scopemeter just to be able to do "carefree" prodding inside mains equipment. (Of course I jest - any "carefree" prodding - even with an isolated scope or differential probes - will eventually kick your ass).

You can fully control the scope via USB but unfortunately the SW is for 32b Windows only (Win 7 and up), no 64b version :-(

That is disappointing. Perhaps it will install and work with one of the compatibility modes in Windows? I know getting the Fluke SW to work is a pain in the A**.

[robert_]

I also bought one, hope it is sort of worth the 200Eur i paid in the end.
I guess it will be good enough for what i need a portable scope for (as im getting rid of that not really portable TDS3014 w/battery now, before it gets entirely worthless).
It probably will be good enough to look at some rotary encoder signals, triac switching and signals like that.

Yes, both channels DO share the same common! It is not grounded (on battery, and with no usb connected). So if one decides to float the common, it would be a really good idea to insulate all other connectors...
Isolated channel scopes are quite a different price class, and i would not buy anything chinese there, as most applications that require isolated channels will deal with high energy. Rather go for a R+S RTH (the one that sucks by far the least, compared to fluke, tek or agisight) here.

[nctnico]

with high energy. Rather go for a R+S RTH (the one that sucks by far the least, compared to fluke, tek or agisight) here.

Ar you sure? I went through most of the isolated input scopes last year and the higher end Keysight models seem to be the best when comparing specs. BTW I did use the Keysight U1620 a couple of times and it seems like a very capable instrument to me which can replace a 2 channel benchtop oscilloscope.

[mnementh]

Dang. Wish I had $300 to gamble with right now.


mnem
This is where I usually put some pithy remark.

[elebot]

Is it not isolated channels? even when using a battery?

I like my Scopemeter just to be able to do "carefree" prodding inside mains equipment. (Of course I jest - any "carefree" prodding - even with an isolated scope or differential probes - will eventually kick your ass).

As mentioned - the oscilloscope channels share common ground with everything else. You could use it floating if you do not need different grounds for each channel, there is nothing connected and the potential is not too high. I mean for example the controls like the scroll wheel or the touch screen are probably not safe for high voltages.

On  the other hand to avoid ground loops issues or slight difference it is still great (not to mention fanless operation  ).

The multimeter is properly isolated.

That is disappointing. Perhaps it will install and work with one of the compatibility modes in Windows? I know getting the Fluke SW to work is a pain in the A**.

You can run it in a virtual machine. I think the main bottleneck is the USB driver - has to be 64b for 64b win...
When asked Micsig they do not have or work on such version (nor they are willing to publish the protocol, yet?). Apparently they main push are the tablets now.

[elebot]

Btw the DMM is there and when connected back the plus socket with the board it seems to be working just fine and within specs. So far. I have not checked all the ranges yet / I am wondering what were the QA issues there.

But since the FW is modified, the only way how to use it is via the PC program. I mean you cannot switch to the DMM function by the big button on the meter but you can use the "virtual version" of the same button on the PC  And then you can even disconnect the scope from the PC, switch DMM functions (voltage/resistance/...).

The recorder can also record DMM values and there the DMM function is not blocked at all (ie. you can do measurements without PC).

[robert_]

Interesting.
Is it possible to flash the regular MS200 firmware image?

[TheSteve]

If this was the isolated input version it would be a great deal.

[elebot]

Interesting.
Is it possible to flash the regular MS200 firmware image?

Unfortunately not.
The upgrade/flashing is done from the PC program (ScopeSuite) and perhaps the check is done there. At least it would indicate the past experience (from an earlier version of the ScopeSuite?) here https://www.eevblog.com/forum/testgear/micsig-technical-support-join-in-eevblog/msg667946/#msg667946 (but that version does not do the trick either).

[robert_]

As i dont have my device yet, i cant really check anything myself at the moment.
How does the device identify itself (if there is any such option, such as the about screen, or to the pc software)?
It would be very good to have a firmware update file that would fit that speciual model, no matter which version but unfortunately, i doubt there is any.
Does that Silabs (?) MCU that seems to handle the front panel do anything (i guess uart, spi or i2c going to the aplication processor?) when the "Meter" button is pressed? Maybe its disabled right there.

[elebot]

I did some more checks of the DMM and here are the results:

• DC mV - almost spot on, well within the specs
• DC V - almost spot on, well within the specs (note that highest voltage I could check was 124V (with error 0.15% so no problem)
• AC mV - low frequencies well within the specs (see below)
• AC V - low frequencies well within the specs (see below)
• Diode test - no specs provided, but seems reasonable (open test voltage 2.748V, shorted test current 1.063mA; voltage drop measurement error under 1%)
• Resistance - below 50 ohms shows about 2 digits low and the specs are +/-1% and no digits (which is strange), so this would be out of specs. Above 50 it is again well within the specs.
• Continuity - fairly slow (seems like ordinary resistance measurement with a threshold for beep, no hysteresis). Same error as resistance above. BUT starts beeping at 18 ohms, specs states 50 ohms. So out of specs in this respect.
• Capacity - TBD (have not checked yet)

Regarding the AC accuracy - manual states frequency range of 10Hz to 20kHz. But above 2kHz (for sine wave) the readings starts going down (-40% at 11kHz, -60% at 18kHz). So there is definately an issue with AC measuments. For AC (TRMS) there is used AD737J. Note that I have checked sine wave only so the TRMS quality was not checked either (but there are no specs for waveforms anyway).

So in summary:

• issues with AC measurements above 2kHz - perhaps some issues with the TRMS converter?
• continuity test threshold different than stated (18ohm v. 50)
• low resistance measurements - open question
• otherwise no issues found (so far)

[nctnico]

There may be an issue with the AD737 when it comes to low and high signal levels. The VC8145 bench DMM uses a similar RMS converter chip and the accuracy/bandwidth of the RMS conversion depends on the input signal level.

[TheAmmoniacal]

So do anyone know why the multimeter has been disconnected? Manufacturing defects? Or just don't meet the specs? (how did you reconnect and enable it?)

[elebot]

There may be an issue with the AD737 when it comes to low and high signal levels. The VC8145 bench DMM uses a similar RMS converter chip and the accuracy/bandwidth of the RMS conversion depends on the input signal level.

I have used 1.7V eff for the frequency response check.

[elebot]

So do anyone know why the multimeter has been disconnected? Manufacturing defects? Or just don't meet the specs? (how did you reconnect and enable it?)

Micsig told me that there were QA issues so they disabled it and are selling it as non Micsig, but who knows...

In HW you just need to reconnect the socket - see the attached photo of how it came (they just cut the wire).

In SW for full functionality you would need to flash the original FW.

[TheAmmoniacal]

So do anyone know why the multimeter has been disconnected? Manufacturing defects? Or just don't meet the specs? (how did you reconnect and enable it?)

Micsig told me that there were QA issues so they disabled it and are selling it as non Micsig, but who knows...

In HW you just need to reconnect the socket - see the attached photo of how it came (they just cut the wire).

In SW for full functionality you would need to flash the original FW.

Did you get it with accessories and everything? How useful is the SPI/I2C triggering? Is there any form of decoding? Is the firmware available and easy to flash onto it?

[elebot]

So do anyone know why the multimeter has been disconnected? Manufacturing defects? Or just don't meet the specs? (how did you reconnect and enable it?)

Micsig told me that there were QA issues so they disabled it and are selling it as non Micsig, but who knows...

In HW you just need to reconnect the socket - see the attached photo of how it came (they just cut the wire).

In SW for full functionality you would need to flash the original FW.

Did you get it with accessories and everything? How useful is the SPI/I2C triggering? Is there any form of decoding? Is the firmware available and easy to flash onto it?

It came with probes, power supply/charger, USB cable and battery. Comparing with the original they removed manual, CD with SW (I guess since both would be Micsig branded),  and multimeter probes 

SW, manual and FW can be downloaded from the web. But you cannot directly flash the FW since there is some check.

I have not tried the SPI/I2C trigger yet but is there in the menu. Decoding is not supported (mentioned as optional addon). I think it is SW option only since for the trigger it has to decode it anyway (so the HW supports it, I guess).

[TheAmmoniacal]

I just messages them about shipping costs, thanks for the heads up on this one!

Makes me wonder if these are hackable to unlock the software features?

[kado]

I just got the shipping coast:

Hello Karsten,

the shipping cost is 75USD total. and it inlcuse ebay freight shipping cost 10%.
Jelin Wei

Shenshen Micsig instruments Co., Ltd.

www.micsig.com

[TheAmmoniacal]

I just got the shipping coast:

Hello Karsten,

the shipping cost is 75USD total. and it inlcuse ebay freight shipping cost 10%.
Jelin Wei

Shenshen Micsig instruments Co., Ltd.

www.micsig.com

At $75 USD for shipping I don't think I'll bother, expensive as hell. I'll ask what other options there are.

[kado]

@ robert_
what did you pay for shipping and tax when you say you got it for 200 € ?

Interesting to know how they charge the shipping coast in relation to the product price.

[robert_]

They do take offers for lower prices, so...
I did recieve it today.
After Tax and some random UPS fees its a bit over 250eur, but still not too bad.
So far, it does work, as expected its a chinese D-Brand scope with limited capabilities, but should do.

Interesting find in the MS200 fw update file:

Code: [Select]

<content>                  <pcode>MS200</pcode>            <type>MicSig</type>             <pkg>0</pkg>            <version>8.0.53.306-N1</version>               </content>

Might be worth trying to change MS200 to SCOPE200? Maybe its that stupid...

[TheAmmoniacal]

They do take offers for lower prices, so...
I did recieve it today.
After Tax and some random UPS fees its a bit over 250eur, but still not too bad.
So far, it does work, as expected its a chinese D-Brand scope with limited capabilities, but should do.

Interesting find in the MS200 fw update file:

Code: [Select]

<content>                  <pcode>MS200</pcode>            <type>MicSig</type>             <pkg>0</pkg>            <version>8.0.53.306-N1</version>               </content>

Might be worth trying to change MS200 to SCOPE200? Maybe its that stupid...

Only 250 euro? What bid did they accept? With the 75 USD shipping + 20-25% VAT?

[robert_]

They dont declare the full value (just as any chinese supplier seems to do), so taxes ended up around 30Eur for me.