EEVblog #480 - 300MHz Owon SDS Oscilloscope

[marmad]

At some company they use a battery powered Owon for simple measurements on high potentials. They don't want to get an expensive scope damaged.

Well this is just plain stupid. The Owon scope is not double-insulated nor does it have isolated inputs. It's rated at 30Vrms maximum - and even the Owon Manual states:

"When powered by battery, the product must have a ground connection. To avoid electric shock, there must be a ground wire connection between ground and the ground port (on the back of product panel)."

Using this DSO on high potentials is an accident waiting to happen.

[Hydrawerk]

I don't work at the company, I don't know the details.

[mikeselectricstuff]

Fine as long as you don't touch any metal.....
Probably doesn't have the issue I encountered many years ago with my first scope :
I thought floating the chassis of an old Telequipment rackmount scope was a good idea when troubleshooting an old live-chassis TV.
I discovered the hard way that although the knobs were plastic, they had metal grubscrews....
 

[EV]

TDS3000 scopes are still bloody expensive.

Yes not from eBay, you must be lucky as I told. I was, but battery is not working. 

[tinhead]

I discovered the hard way that although the knobs were plastic, they had metal grubscrews....

welcome in club :\

[marmad]

Fine as long as you don't touch any metal.....

From a Tek document on the subject - first specifically about it's TDS3000 battery-operated DSOs which are NOT double-insulated (the same applies to the Owon):

'While in battery operation and following environmental specification limits for the TDS3000 Series, it is safe to “float” the “signal common” for making measurements provided you do not connect a signal greater than 30 VRMS (>42 Vpk) from earth ground to either the probe tip or common lead.'

Secondly, about the practice of floating oscilloscopes in general:

'“Floating” a ground referenced oscilloscope is the technique of defeating the oscilloscope’s protective grounding system – disconnecting “signal common” from earth, either by defeating the grounding system or using an isolation transformer. This allows accessible parts of the instrument such as chassis, cabinet, and connectors to assume the potential of the probe ground lead connection point. This is dangerous, not only from the standpoint of elevated voltages present on the oscilloscope (a shock hazard to the operator), but also due to cumulative stresses on the oscilloscope’s power transformer insulation. This stress may not cause immediate failure, but may lead to future dangerous failures (a shock and fire hazard), even after returning the oscilloscope to properly grounded operation! Not only is floating a ground-referenced oscilloscope dangerous, but the measurements are often inaccurate. This results from the total capacitance of the oscilloscope chassis being directly connected to the circuit under test at the point where the common lead is connected. At higher frequencies, severing the ground may not even break the ground loop as the line-powered instrument exhibits a large parasitic capacitance when floated above earth ground.' Etc.

[adnewhouse]

I encountered the same problems saving to a USB drive. Updating the firmware fixed the issue for me. I agree with most of this review. The update times really do suck. The only consolation is that in a few years when I buy a "real" scope this one can be used as a portable battery powered one.

[AlphZeta]

Is it just me or anyone else had noticed, the waveform look significantly different on this scope than the same waveform on either a Rigol 2000 or the older DS1052E? (I am talking about the waveform generated from the LeCroy demo board). It could be because of the higher bandwidth but not sure.

Also, it would be great if Dave could feed in a 300MHz signal to see whether the scope can indeed handle that bandwidth (or using a avalanche pulse generator to see how fast the signal rises).

[EEVblog]

It would be interesting to see if Dave could take a look at Siglent and GW Insteak also, although
the advertisement on the blog 
I believe in Daves integrity, but it could be fun

Trio smart cal have tons of siglents, so can easily get one. The GW needs another video, it has more to offer I think.

Sent from my Nexus 7 using Tapatalk 2

[EEVblog]

Also, it would be great if Dave could feed in a 300MHz signal to see whether the scope can indeed handle that bandwidth (or using a avalanche pulse generator to see how fast the signal rises).

The Owen isn't worthy of any more air time!
Sent from my Nexus 7 using Tapatalk 2

[Hydrawerk]

I have found the worst scope ever and it's not Owon. https://www.eevblog.com/forum/testgear/welec-w2000a-another-weird-oscilloscope/msg244383/#msg244383

[Nermash]

I think I have said it once before, but man I wish Dave could review this welec, only for the rants, McFlys, and all others

I had this scope, impressive specs for the time and still good these days, like full 1 Gs/s for each channel, vga size screen, Agilent like looks, open source fw with at least one excellent implementation by Blueflash.

It had 4x 250 Ms/s Maxxim adcs per channel, and one Cyclone 2 fpga with Nios 2 softcore running the whole thing, including the display.
IMO the worst thing was the frontend, very noisy on some ranges, and clunky UI which felt nimble as a freight train.
Interesting thing was that they sold 100 and 200 MHz version, but they were 100% identical !??! No passive bw limiting, no VGA, frequency response wavy enough to get sea sickness. On the great mysteries remained how did they choose which one is 100 and which one is 200 MHz.

Than noisy frontend caused it to trigger on noise alone, that irritated the hell out of me, specially since it was my first dso. I replaced it with SDS7102 and it felt like someone now going from Owon to Agilent  That is why I replied to Dave on twitter, when he called Owon the worst scope ever, "you obviously haven't had a chance to use welec" 

[Hydrawerk]

The Welec scope had even bloody slow waveform update rate.

Timebase    50ns/div to 5sec/div
Signal Refresh Rate
   at timebase setting to 50ns/div:
Single Channel Operation
approx. 10 recordings/sec
Dual Channel Operation
approx. 5 recordings/sec
Three Channel Operation
approx. 3 recordings/sec
Four Channel Operation
approx. 2 recordings/sec

On the other hand, in 2007 you probably could not buy a decent chinese scope in Europe. Like Rigol or Siglent.

[ben-s]

I have an SDS7102, the 100MHz version of this, which I've owned for about a year.
I absolutely agree that yes, it does have some really stupid bugs and the UI isn't great, however it's not complete junk for certain applications.

Some features are unusable or less than useful; the copy button doesn't work very well, usually defaulting to wave rather than image mode, and the PC software is frankly useless. The persistence is not robustly written and the cursors are not very well implemented (based in the frame buffer, as far as I can tell, so they don't stick to the wave if you pan or change the timebase), but for what it is, I believe the 100MHz version represents reasonably good value for money.

When I bought it, I required a cheap scope with good memory depth and a decent screen, and at the time the memory depth on the Owon blew everything in the low end scope market, including the Agilent 2/3000x series, out of the water. (I never understood Agilent fitting the otherwise excellent 3000x with only 2 or 4 MB).
The other Chinese scopes are at best a couple of meg, often shared between channels, whereas the Owon has 10MB per channel.
This has of course been significantly beaten by the new Rigol 2000 series now, but that option didn't exist at the time..

The battery is also a very useful addition (it lasts about 3-4 hours)

Successive firmware updates have improved some of the glitchiness, albeit nothing like all of it.


If you go into buying or using one of these expecting an Agilent or higher end Rigol, you will without doubt be disappointed. If you go into it expecting a compromise to get good memory depth and a decent screen at a very low price, you will likely be reasonably satisfied.

I deal with a lot of one-shot events containing a lot of detail, which many higher end scopes struggle with due to their limited memory.
Try tracing a short cap discharge followed by a several-second recharge cycle on a scope with limited memory, and you'll soon be tearing your hair out when you want to zoom in on the detail of the short discharge event.


If I was buying again, I'd probably spend the extra money and get the Rigol 2000 series; but (and I'll no doubt get some odd looks for this) I don't regret buying the Owon.

[mswhin63]

I must admit I was hoping to save money to get a Rigol 2000 series and I tried, but expenses were just prohibited. So I purchase the Owon from a couple of mediocre reviews that were not very convincing. It arrived the next after this review and I was SHITTING myself with anticipation. It may be the reason why I was such a terd recently.

So far I have not found a lot of the more severe bugs displayed and mentioned in the threads so far, noise is a problem when the probes are connected, I assuming this is from the lack a shielding but the other bugs do not appear. I had to buy something until I can afford a real decent scope.

It is possible Dave was given a dud either deliberately or accidentally. One thing I noticed is the menu auto off default is 25 seconds, so someone had played around with the scope before Dave got it.

I am now not convinced of the review, there are a lot of personal views as well. I also found the scope extremely intuitive as I managed to work out nearly all menu functions without the need of the manual, and I still haven't read it.

I will still not apologise for my assessment of a review I recently talked about as it was a one of the reviews that I decided to purchase it. He gave a glowing review compared to other scope of the same cost.

[marmad]

I am now not convinced of the review, there are a lot of personal views as well. I also found the scope extremely intuitive as I managed to work out nearly all menu functions without the need of the manual, and I still haven't read it.

I will still not apologise for my assessment of a review I recently talked about as it was a one of the reviews that I decided to purchase it. He gave a glowing review compared to other scope of the same cost.

Man, you are all over the map. First, you wrote that Dave's review proved my review was "crap" (even though we both mention many of the same problems) - and you also wrote that my review was "totally unconvincing", I guess because it apparently convinced you to buy the DSO. Now you're "not convinced" about Dave's review - and even though you appear to be happy with the DSO - your assessment of my review as crap hasn't changed. I'm sorry, but I can't even follow your logic.

BTW, I don't understand some people's ideas about what a review is. The word 'review' comes from Middle French: 'to see again' - and it's a subjective process - not objective. Of course there are personal views present - that's what it is: one person's views on a particular device, movie, book, etc. Dave's ideas (or mine) about what is ergonomic - or what constitutes good interface design - is personal, and may or may not correspond with yours. That's where it becomes your responsibility to judge the supplied information and opinions and decide whether they correlate with your own experiences and opinions.

[Hydrawerk]

Marmad's review was OK. He showed many features of the scope.

[mswhin63]

Maybe it is my upbringing, if I was to comment in my old ways I would most probably offended more than just you and your supporters. I grew as a hard case and maybe that is just what I am. Your speaking voice is unconvincing and all over the place, but unfortunately so are many other engineers which I assume you are. I consider Dave as one of the exceptions and talks very much on a worker level as I used to be. I am allowed to have an opinion and that is how I am no holes barred. Straight out no bullshit, it is also my family life learning sign language is also a no holes barred language (eg: either fat or not! not this bullshit political correctness). If I don't like the way you talk then that is how I am. I don't create videos myself purely because I would have to be more restrained that Dave is now.

I have seen a couple of your reviews so out of the ones you provided the OWON was the best of the cheaper models. Mind you it was Daves assessment that worried me and may still do. I have only had a couple of days to play with it plus no real option to return it either, but at the moment trying to prepare for 2nd Year electrical exams next week so I don't have a lot of time to play with it more comprehensively.

Man, you are all over the map. First, you wrote that Dave's review proved my review was "crap" (even though we both mention many of the same problems) - and you also wrote that my review was "totally unconvincing", I guess because it apparently convinced you to buy the DSO. Now you're "not convinced" about Dave's review - and even though you appear to be happy with the DSO - your assessment of my review as crap hasn't changed. I'm sorry, but I can't even follow your logic.

BTW, I don't understand some people's ideas about what a review is. The word 'review' comes from Middle French: 'to see again' - and it's a subjective process - not objective. Of course there are personal views present - that's what it is: one person's views on a particular device, movie, book, etc. Dave's ideas (or mine) about what is ergonomic - or what constitutes good interface design - is personal, and may or may not correspond with yours. That's where it becomes your responsibility to judge the supplied information and opinions and decide whether they correlate with your own experiences and opinions.

[Paul Moir]

Why don't these companies bother to have someone who actually knows English help them with the text?

Personally, I've always appreciated this common fault with Chinese companies.  I would rather them not spend my money on marketing drivel or even a manual that's a pleasure to read.  I just need enough to understand what's intended to be communicated even if it requires a little effort on my part.  To me it's not unlike technical jargon or listening to someone with a strong accent.

Also, I'm sure when Bob in the Albuquerque office does his Finnish translations using Google they come out at least equally awful.   

[Rasz]

Personally, I've always appreciated this common fault with Chinese companies.  I would rather them not spend my money on marketing drivel or even a manual

Except it goes beyond that. They avoid spending on native English speaker sure, but they also avoid UI experts (or anyone who has a slight idea how UI should work), usability experts, or even decent programmers. EVERY SINGLE Chinese gadget has shit for firmware. They are so clueless they even manage to make bugs in Flashlight (mode switching with one button) firmwares.

Also, I'm sure when Bob in the Albuquerque office does his Finnish translations using Google they come out at least equally awful.   

As far as I know Finnish is not Internationally spoken language of the world. Mandarin, Spanish and English are.

[Yaksaredabomb]

Why don't these companies bother to have someone who actually knows English help them with the text?

Personally, I've always appreciated this common fault with Chinese companies.  I would rather them not spend my money on marketing drivel or even a manual that's a pleasure to read....

That's an interesting point!  I'd never thought of it that way before.  Is grammar on the box and in the manual really "value added"?  Whatever the employee's time is spent on, the money to pay them is all coming from somewhere: the customer's pocket.  Same thing with how businesses pay taxes, btw - with money from their customers   Anyhow, a whole different perspective.  And just because their grammar is poor, logically speaking that in and of itself proves nothing about whether their programming or circuit design skills are poor.

I had sided with the "if they didn't get this obvious thing right, what assurance do I have they got the less obvious things right?" crowd - and I might still side with them.  For instance, everyone learning how to put a resume together is told over and over again, no typos, no mistakes, it must be impeccable - even have other people proof read it if possible.  The concern is that any error may be counted against you as a sign of poor attention to detail or something worse.  Perhaps there is usually a valid reason to be concerned, too.  Whether justified or not I'll admit I have judged things this way.

[Bored@Work]

That's an interesting point!  I'd never thought of it that way before.  Is grammar on the box and in the manual really "value added"? 

Is that really the only question? Isn't it also as much about respect, or the lack thereof, for their customers with a western culture background?

When you, as someone from the west, want to do business with Chinese you are constantly told to always show respect for their culture, to always rub them the right way, never tell them they messed something up, etc. bla bla bla. E.g. with my employer we have to go through two seminars before we are supposed to deal with our Chinese suppliers (yes, suppliers, not customers), to avoid, heaven forbid, to make them the least inconvenient. In return however, they simply shit on us.

We had that discussion about the constant stream of unsafe devices like wallwarts from China in the past. They just don't care if a few people in the west die. The grammar and spelling on the box is just an expression of giving a shit about their customers. Insofar it is an indication how the stuff looks inside. They don't want to get it right on the outside, and they don't want to get it right on the inside.

[nitro2k01]

As far as I know Finnish is not Internationally spoken language of the world. Mandarin, Spanish and English are.

I'm not sure I would call Mandarin an internationally spoken language. It's the language with the most native speakers, yes, but the vast majority of those are confined to a relatively small area of land, unlike English and Spanish (especially English) which are spoken all over the world, often as a second language. If you would drop me off randomly anywhere in the world, and I could only speak one language, I would choose English, as there's likely someone nearby who can speak it.

[TRIO_Smartcal]

Anyone want a bargain?
There's only one at this price and you've seen it in the review.  We tested its bandwidth and it met spec.
As others have said, if all you want is sample rate, bandwidth and 10M memory, then its not bad at all at the advertised price.

http://www.triosmartcal.com.au/owon/2800-owon-sds9302-300mhz-2-channel-oscilloscope.html

[Yaksaredabomb]

...
Is that really the only question? Isn't it also as much about respect, or the lack thereof, for their customers with a western culture background?

When you, as someone from the west, want to do business with Chinese you are constantly told to always show respect for their culture, to always rub them the right way, never tell them they messed something up, etc. bla bla bla. ....

Ok, an excellent point.  I guess as a Christian and engineer, I'm either desensitized to cultural disrespect or oblivious to it due to .  Sure, among some people and in some places I expect others to make a deliberate effort to be polite (and sure it would be nice if everyone did, everywhere, all the time).  Personal attacks are almost universally unacceptable.  But I've never been actually offended by Chinese products with poor English grammar on their box or in their manual.  I don't know the first thing about their grammar or culture so I can hardly justify being offended when they don't get mine quite right.  I can wonder why they didn't make more of an effort though, and wonder what that might mean about the product itself, and I can laugh at it .

I don't deal with any Chinese suppliers or customers though and haven't been through the sensitivity/cultural training etc that seems to be required to do so.  I have heard of the stereotype that they're very concerned about respect and "saving face", but when they release a box like this absurd Owon one to the world it can be hard to take that stereotype seriously .  If it really does seem like a double standard then yes, I can understand getting frustrated and offended over such disrespect for Western customers.

Of course on top of that it seems all many care about is profit and price.  Consumers generally want the cheapest possible prices (myself included).  Many will choose another product or vendor due to relatively small price differences, regardless of "green" or "ethical" concerns.  At the same time, shareholders demand higher stock prices and executives demand massive compensation (whether it makes sense to compensate them so much is another issue).  So in this fight between profits and price it's absolutely no surprise to me that unsafe devices are produced.

That's where (hopefully) certifications and independent reviews etc can step in to filter out the worst of the unsafe products before they get to the customer.  Even then, some will get past and some will have terrible consequences.  That's just the world culture in 2013, or so it appears to me.  That may be unacceptable and we can try to change it but I think that's how it will be until "the money" says differently.  I don't take China's offenses personally.