REVIEW - Owon SDS7102 - A look at the SDS series from Owon

[TomC]

Hi Skimask,

If you are talking about the Oscilloscope analysis software, yes, It's been working on both my laptop and desktop running Win 7 Home Premium 64 bit. Not quite sure what you mean by "Test mode", but it's been a while since I installed the drivers and software.

[Skimask]

Ya, I'll be damned if I can get it to work and/or connect, Win7 H/P 64b

The "test mode" I speak of is mentioned in the OWON software "Help" section, where it has you put Windows into the "test mode" where it basically takes any set of drivers and runs with it without asking for digital signing or any of that stuff.

At any rate, asks for the drivers, loads the drivers, won't connect, plain and simple.  Now...maybe I'm forgetting to turn on something on the 'scope itself, or move a setting.  I dunno.  Didn't see anything specific in the PDF manual.

[mikerj]

Is anyone else's 7102 microphonic?  I noticed that tapping the case between the two channel BNC inputs caused channel 1 voltage to move a little, and if I flick the case with a finger nail I can get up to ~200mv damped sinusoidal (ish) waveform.

[TomC]

Ya, I'll be damned if I can get it to work and/or connect, Win7 H/P 64b

The "test mode" I speak of is mentioned in the OWON software "Help" section, where it has you put Windows into the "test mode" where it basically takes any set of drivers and runs with it without asking for digital signing or any of that stuff.

At any rate, asks for the drivers, loads the drivers, won't connect, plain and simple.  Now...maybe I'm forgetting to turn on something on the 'scope itself, or move a setting.  I dunno.  Didn't see anything specific in the PDF manual.

Did you download the Labview package from the Owon site?
One  of the folders in this package contains the USB driver. I'm pretty sure that's what I used to install the driver back when I first got the scope.

The PC software packages that I have don't seem to include the USB driver although the instructions for installing it are included.

[TomC]

Is anyone else's 7102 microphonic?  I noticed that tapping the case between the two channel BNC inputs caused channel 1 voltage to move a little, and if I flick the case with a finger nail I can get up to ~200mv damped sinusoidal (ish) waveform.

Does this happen with nothing connected to the BNCs?
If you had the probes connected try with nothing connected. It could be a bad connection at the BNC.

[rf-loop]

Is anyone else's 7102 microphonic?  I noticed that tapping the case between the two channel BNC inputs caused channel 1 voltage to move a little, and if I flick the case with a finger nail I can get up to ~200mv damped sinusoidal (ish) waveform.

Yes it is some amount microphonic. Some analog front end versions more than others but I have never done deep tests and compared versions because normally this is not real problem. It means that some individual scope may have more and some less. And also Owon is not alone. This is common problem. But it depends highly what component are used, layout on the PCB, and whole mechanical construction. 

Perhaps main reason (but not exactly whole only one reason)  is this:

Microphonic Effects
Of much less concern, yet still important, especially
in audio applications, is the microphonic or piezoelectric
effect. Barium titanate which is the base ceramic
material for most dielectric systems will exhibit microphonic
effects. It is not very difficult to take a Y5V
capacitor and put a DC bias with a small signal 1kHz
sine wave and get the capacitor to “sing”. Tantalum
capacitors exhibit no microphonic effects. The experiment
done by AVX involved the opposite phenomena
whereby the part was shaken while under bias and the
resulting generated voltage was measured.

Quoted text is from:
COMPARISON OF MULTILAYER CERAMIC
AND TANTALUM CAPACITORS
by Jeffrey Cain, Ph.D.
AVX Corporation




I can tell for curiosity that example usual coaxial cable is  "microphonic", you knock it and all changes, you bend it and all changes..etc... you sing and you can listen it using coaxial cable as microphone (but of course these findings need special equipments)
Try use sensitive and accurate VNA without special cables... with normal coaxial cables all are bullshit and today you measure something and next day you have moved cables and all have changed... PCB's are microphonic... L,C,R all change with mechanicalvibration. But these are of course low level changes and nothing meaningful in this particular case.
Owon front end (and also many other manufacturers) some components are highly microphonic and it can see in races if you knock / vibrate / shock amplifier/attanuator circuit.

In many "high end"  and  "state of art"  test equipments some sensitive parts / blocks are well isolated from external mechanic noise and acoustic noise and also used many construction details for minimize these effects in eleronic circuits but also mechanic. But these kind of equipments are made and developed by well experienced real professionals and this kind of professionals are quite rare.

In oscilloscope front this level of microphonic is normally not real problem in normal use.

If someone find this more and some less, main reason is that there have been many changes in front end circuit. Some small changes in different versions but also there have been some major changes. (example from IC amplifier to dual pathway discrete fet amplifier.)  Then, also some component may have changed in different manufacturing lots. (example same voltage, same capacitance but different manufacturer and/or type.

[rf-loop]

Here one example with other brand of scope.

Shock made using "medical doctors" rubber hammer. (This is good electronic workshop tool)
Shock directed axially to input BNC outer GND part.
(shock was "hard" and not this "knock" what doctors normally use.)
This rubber hammer do low frequency shock (as can see)
Input BNC open and 5mV/div and 1Mohm impedance set.
It can also repeat with example tektronix analog scopes. But taking image without triggered scope camera is "impossible".

[Skimask]

Did you download the Labview package from the Owon site?
One  of the folders in this package contains the USB driver. I'm pretty sure that's what I used to install the driver back when I first got the scope.

The PC software packages that I have don't seem to include the USB driver although the instructions for installing it are included.

I Google'd "labview Owon" and came up with something completely different from "Owon PC software".
Downloaded that.  Works now.
Pretty slow updating on the PC though...almost unusable.  But good enough for me.

Thanks for the tip   ...< ->beer  >...

[mikerj]

Is anyone else's 7102 microphonic?  I noticed that tapping the case between the two channel BNC inputs caused channel 1 voltage to move a little, and if I flick the case with a finger nail I can get up to ~200mv damped sinusoidal (ish) waveform.

Does this happen with nothing connected to the BNCs?
If you had the probes connected try with nothing connected. It could be a bad connection at the BNC.

It happens with nothing connected,  I assumed it would be down to ceramic caps in the front end.

I just powered it up and took the following pics with nothing connected to either input (sorry for phone pics, Owon software doesn't seem to like Windows 8 64 bit).

This is a fairly gentle tap:


And this is a hard flick with a finger nail:


Pk-pk voltages look worse than I originally thought.

[TomC]

It happens with nothing connected,  I assumed it would be down to ceramic caps in the front end.

I just powered it up and took the following pics with nothing connected to either input (sorry for phone pics, Owon software doesn't seem to like Windows 8 64 bit).

This is a fairly gentle tap:
And this is a hard flick with a finger nail:
Pk-pk voltages look worse than I originally thought.

What I see on my scope with a hard flick with a fingernail is about what you see with a gentle tap!

I'm not sure if what you are seeing is just normal micro phonics as rf-loop describes in his post, but to me, it seems a bit excessive, like a bad connection someplace in the front end. If your scope is under warranty I would contact Owon and attach the pictures to the e-mail. If you just give them a link to photobucket or some other web drive they may not be able to see them in China.

[TomC]

I Google'd "labview Owon" and came up with something completely different from "Owon PC software".
Downloaded that.  Works now.
Pretty slow updating on the PC though...almost unusable.  But good enough for me.

Thanks for the tip   ...< ->beer  >...

So it seems that you have the USB driver working now (with Labview). As far as I know this is the same USB driver that the PC software uses, so I would think the PC software should also be working now! Have you tried it?

[Skimask]

Ya, that's what I meant.  It all works now, but again, very slow updates from 'scope to PC.  Better than nothing???

Although my little Xprotolab Portable updates many times per second vs. The Owon software at about 1 FPS.

[Sarasir]

Hi TomC,

came to the decision to bring the 1.9V switcher back to the main PCB because obviously the ADC needs a very low impedance supply. At least now it's clear why they have put this switcher there. The moment the mode switching wants to go from low power to normal mode probably sees a not stiff enough supply and refuses to go over. Thats my problem at the moment that ADC stays in low power mode.

Will put it in a small tin box to fit it in between the keys PCB and the main PCB.

Will take some time especially as I sit here with a swollen cheek and have to see the dentist again after a 4 houres session on tuesday....



And to the microphonic behaviour discussion:

Has any of you thought about the rectangular shields who are soldered just on three points?

If one of them is a bit loose it could make up something like a condenser mic!

[mikerj]

The scope is probably not in warranty.  I bought it new, boxed and unused but it was bought by a previous over a year ago and never used.  I'm quite happy to take it apart and have a look so I'll let you know if I find anything.

[rf-loop]

The scope is probably not in warranty.  I bought it new, boxed and unused but it was bought by a previous over a year ago and never used.  I'm quite happy to take it apart and have a look so I'll let you know if I find anything.

Owon factory warranty is 3 year.

[rf-loop]

This microphonic is sum of many things.  Normally it do not affect measurements at all. It may be problem in some heavyvibrating enviroment as example in wechile  etc.  And even if this is any kind of problem it is easy to solve using sevral methods. If it is problem on the table this effect is easy to minimize.

Why it is so microphonic.
Construction is so that BNC connector go directly axially to PCB and there very sensitive area.
This outer shield of BNC is directly soldered to PCB. Knoc it and all force and vibrations go to PCB and its direction is worst possible

If BNC is first fixed to some metal base and after then example side direction from PCB situation is perhaps more easy. (as example in Siglent, Rigol DS1000 and many others)
In very very early version BNC did not go at all directly to PCB. It was not microphonic.

If want that mechanic vibration do not affect this construction need be different. It can still construct to inside these scope dmensions but very different mechanic. Also front amplifiers layout on PCB can do different and isolate bending forces by cutting PCB around amplifier sensitive parts so that even if main PCB have some bending vibrations/waves they do not bend front end amplifier.
But all these need new design.
Also some componet need carefully select. (specially some capacitors in front end)
Now it can ask - is it forth of this price?
Do not knokc and hammer your scope when you do sensitive measurements and this modification of working practices do not cost anything. It is free.

If you want measure nail  knocs pleasre also put BNC cover cap on it. (Real BNC metal cap)
It enclose BNC input so that external electric field can not affect to 1Mohm around 10pF very sensitive input)  Put your finger near to open input and agen you have electrical phenomenon which may wonder.

~
But If I want listen my water pump roller bearings I can connect  nylon rod from bearing box shield to my scope BNC and "listen" with FFT these bearings condition ... (    )

[TomC]

Hi TomC,

came to the decision to bring the 1.9V switcher back to the main PCB because obviously the ADC needs a very low impedance supply. At least now it's clear why they have put this switcher there. The moment the mode switching wants to go from low power to normal mode probably sees a not stiff enough supply and refuses to go over. Thats my problem at the moment that ADC stays in low power mode.

Will put it in a small tin box to fit it in between the keys PCB and the main PCB.

Will take some time especially as I sit here with a swollen cheek and have to see the dentist again after a 4 houres session on tuesday....



And to the microphonic behaviour discussion:

Has any of you thought about the rectangular shields who are soldered just on three points?

If one of them is a bit loose it could make up something like a condenser mic!

Yes, I agree, getting the 1.9 supply close to the ADC sounds like the best course of action! Let's hope that's enough to the get the ADC back into action.

[TomC]

The scope is probably not in warranty.  I bought it new, boxed and unused but it was bought by a previous over a year ago and never used.  I'm quite happy to take it apart and have a look so I'll let you know if I find anything.

In case you haven't seen it yet, here is a link to a video that shows how to take the SDS7102 apart. Just be careful with the Power button and hold it down while taking the cover off, this is not shown clearly in the video.

[onlooker]

Sorry side tracking again the present long stretching trend a little.

The purpose of this post is to let others who like me lost the factory calibration to know: DIY "factory" calibration of SDS7102 is doable. In fact, no inside pots need to be turned; it is all digital from the front/side panel.

For those who may not know, the tx file on your SDS7102 contains 194+ machine specific calibration constants.
 
I accidentally overwrote the factory tx file (the os and fp files too) on my osc and I did not have a backup (not equipped to do the backup). The problem with os and fp was easy to correct. But the problem with tx is not. Some days ago I asked around about a sample tx file for a certain SN range.

I did not get any answer back; Then, I proceeded to do my own DIY calibration: the unofficial "factory" style.  To calibrate the 194 constants has been tedious, but I am about 80% done. The only thing left is the trig-level offset calibration. It involves 24 constants, but their calibration requires more trail-and-error process.

When I have more free time and if there is an interest, I will summarize the calibration steps in a new thread.

[TomC]

Hi onlooker,

I have no idea how to look at, read, or extract the tx file from the SDS7102. Perhaps other members that may have a scope within the target serial number range are in the same boat, and therefore unable to help you. My scope's serial is 1246320 which I think is too new for your needs. However, I'm pretty sure some of the other regulars in this thread own scopes of the proper vintage. Try posting more information on how to access this tx file and perhaps one of them will be willing to help you!

[onlooker]

TomC,

Thanks for replaying. I guess I did not make myself clear.

I have already figured out how to do the calibration without a know good tx file. In fact, I have mostly done my calibration. The remaining part is just a matter of time. 

But, I also like others in the same boat as me to know it is doable and when I have time I will share the steps in a new thread. To write up the whole thing in a concise manner takes time.

By the same token, if someone has something to share about factory calibration, I will be interested to read.
 

[mohandes]

hi TOM
some Guru say SDS7102 ( Owon ) not good and Riogol more better . are you agree ?
can you get video  and put here of your Owon scope ?
i stay between Owon or Rigol to choose ?   

[TomC]

Hi mohandes,

It all depends on what's important to you, or if you only use your scope for your hobby like me, then it probably only depends on what you like!

For example, I attached a couple captures from the VCO of a modified TV tuner that I plan to use to build a HF RF generator. I like to be able to view these HF signals on the scope, I don't think I can get a Rigol in the SDS7102 price range that can do this.

Try to figure out what's important to you, or what you like. That will probably help you more than anything else to make your decision!

Edit:
The smooth appearance of the signals in the attached captures is due to sin x interpolation. In practice, at 1GS/s, this works without much aliasing to around 400MHz. In theory, with a perfect filter, it should work to around 500MHz.

[rf-loop]

It looks that newest FW (have been available from Owon some weeks) give max 260 wfms/s 
With settings: 1us/div, one channel, 1k mem, dots and not any menu open and trig auto.
With settings: 50ns/div, other sets same give 250wfms/s

With eyes and real signals this improvement looks visually even more
Sad that it do not have intensity grading in normal display mode. There is 8 step intensity grading only in persistence mode but persistence drops wfms/s rate to low.

Old "up to" limit was 35 wfms/s. (it was just like conventional series processing DSO )


Also with other settings there is more or less improvement if compare to old.

max 35 to max 260 is nice FW improvement without touching HW.

[lemon]

Yes, I have seen the same behavior after the fw upgrading.
In some situations the improvement is huge, only by fw.

For me the only big missing is the Vertical Fine adjustment and the appear of all measurements in real time.

I don't think so that these changes are difficult from Owon.
Unfortunately, Owon's customer feedback politic wasn't appropriate.

Personally, three times I sent my suggestions for fw changes, but never had an answer about this.