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

[TomC]

Five more days in this beach with clear water!

Looks like paradise! I love the beach too, that's why I live in Florida near this Gulf beach.

[TomC]

Please for comparison reasons, repeat the test of noise ground as decribed at post #1330, page 89 and give us the Vp-p value and the capture.

More about:

The "Mainboard" also have a DC/DC connected to ~5.54V it generate noise that goes to the analog power of the input stage. This DC/DC supply power to the entire DAC. 

Below the shielding metal sheets of the input stage there is a 5V LDO, connected to ~5.54V (i.e Vdo <0.54). And if Owon did not put any filters (F.Bead) in the input of the analog power for the DAC, less to the input of the analog power for the input stage. This LDO is able to reject only some frequencies <1MHz. Similar for the 7905.


Yes, please for comparison reasons, repeat the test of noise ground as decribed at post #1330, page 89 and give us the Vp-p value and the capture.


More:

- To correct variations between channel 1 and 2 in some oscilloscopes Owon add extra resistors there where Owon think.   
- The 5V regulator thermally affects more the channel 1, since it is closer, this explains its greater DC drift. 


Now I do not think Owon would like to save money, rather it seems that, did not even know how to make the oscilloscope. 

Well done Owon... This is not an oscilloscope, is shit. 

Carrington, I agree that the SDS7102 is not a perfect oscilloscope, that's probably the reason this thread is quickly approaching page 100. In regard to your comment about the low drop linear regulator (LDO), I'm glad that Owon at least had the good sense to use linear rather than pollute the input stage with another PWM converter. Owon is fairly new in the Test Instruments arena, so I'm sure that there are quite a few tricks they haven't learned yet. However, many of us can't afford a scope from the high end manufacturers, and Owon's SDS7102 features/price ratio is very attractive. I, for one, don't regret buying the SDS7102, it doesn't fulfill all my wishes, but it reasonably fulfills my expectations for the price I paid. We all wish we could get better performance, so we continue to tinker with new ideas on how to improve the SDS7102 ourselves. This doesn't mean that we totally dislike our scopes, and most of the negative comments you may occasionally see are just venting.

[Carrington]

Carrington, I agree that the SDS7102 is not a perfect oscilloscope, that's probably the reason this thread is quickly approaching page 100. In regard to your comment about the low drop linear regulator (LDO), I'm glad that Owon at least had the good sense to use linear rather than pollute the input stage with another PWM converter. Owon is fairly new in the Test Instruments arena, so I'm sure that there are quite a few tricks they haven't learned yet. However, many of us can't afford a scope from the high end manufacturers, and Owon's SDS7102 features/price ratio is very attractive. I, for one, don't regret buying the SDS7102, it doesn't fulfill all my wishes, but it reasonably fulfills my expectations for the price I paid. We all wish we could get better performance, so we continue to tinker with new ideas on how to improve the SDS7102 ourselves. This doesn't mean that we totally dislike our scopes, and most of the negative comments you may occasionally see are just venting.

"However, many of us can't afford a scope from the high end manufacturers."
Yes,  I agree, I buy one for the price. The problem is that in the end is expensive, think:
  -All the lost time, looking for a solution, on how to improve the SDS7102 ourselves.
  -Money spent in parts, etc.
And after check how OWONs customer service work, do you think that they will apply the warranty?
I doubt.

OWON could done it much better, and maybe with the same costs.
Anyway if you're happy with it, then perfect, this is an imperfect world.
But please OWON at least tries to attends decently to the customer.
 
"Owon is fairly new in the Test Instruments arena."
That's not our problem, OWON should know what he does. Don't you think?

I can assure you that after this experience I will never buy any product from OWON. No matter how cheap.

I'm tired, I don't want talk more about SDS7102's issues.

Cheers.

[marmad]

Carrington, I agree that the SDS7102 is not a perfect oscilloscope, that's probably the reason this thread is quickly approaching page 100. In regard to your comment about the low drop linear regulator (LDO), I'm glad that Owon at least had the good sense to use linear rather than pollute the input stage with another PWM converter. Owon is fairly new in the Test Instruments arena, so I'm sure that there are quite a few tricks they haven't learned yet. However, many of us can't afford a scope from the high end manufacturers, and Owon's SDS7102 features/price ratio is very attractive. I, for one, don't regret buying the SDS7102, it doesn't fulfill all my wishes, but it reasonably fulfills my expectations for the price I paid. We all wish we could get better performance, so we continue to tinker with new ideas on how to improve the SDS7102 ourselves. This doesn't mean that we totally dislike our scopes, and most of the negative comments you may occasionally see are just venting.

C'mon though - I made the review and started this thread almost precisely two years ago - and Owon hasn't bothered to upgrade the firmware with even the simplest of features which I (and many others) felt were missing - and some of them would have been quite easy to add - so it doesn't seem to me as if Owon has learned anything in the last two years (at least in terms of supporting and satisfying their user base).

[lemon]

I think that we judge the Owon with wrong parameteres.
Before two years when Owon presents this model the competition was Rigol and some Atten in low range of oscilloscopes.
The SDS Series has some plus vs others like large and better screen, deeper memory and some others. Before two years I think that them was enough, but not today.
They aren't going to presentation a new marvelous fw, for them it is adequate this basic fw.
Probably, they have different philosophy or their target group is difference from that of an experience user.

Today the things are different, more competitors and the new Rigol 2XXX Series one level upper with double price of course!

For me the time was expending for improvement the noise ground level is like school and I haven't problem with this. I am sure for others owners like Carrington this is a lost time and the nervous system is going to break!
Different people with different needs!

@ TomC = marvelous place and I think that your choice is right. The place that presents before is held to South Peloponissos (Laconia, Marathias beach). The water is deep clearly, if you dive with apnoia you can see over 20 metres.

[TomC]

C'mon though - I made the review and started this thread almost precisely two years ago - and Owon hasn't bothered to upgrade the firmware with even the simplest of features which I (and many others) felt were missing - and some of them would have been quite easy to add - so it doesn't seem to me as if Owon has learned anything in the last two years (at least in terms of supporting and satisfying their user base).

Wow marmad, the thread that you started hit a new milestone! 100 pages, Congratulations!   

I'm also disappointed with the progress in the firmware side, more so with unresolved bugs than the lack of new features. Owon's behavior in my opinion is counterproductive, but is their choice to decide where they want to go in the future. The main point I've attempted to make, is that in spite of the shortcomings, we don't all consider our Owon scopes to be totally manure. I'm still enthusiastic about the many things that I can do with my Owon DSO that were simply not possible with my old Tek CROs. I know that you now own a 70MHz Rigol DSO with very nice features. In my case, I already owned two 60MHz Tek CROs, so I wanted to get at least 100-200MHz for a new DSO. The SDS7102 offered 100MHz and was usable to 200MHz for a price I could afford. So I still think I did fine for my needs. But I do agree that Owon could do better, at least in popularity, if they would cater to user base needs and desires. There is nothing like word of mouth, in my opinion!

[marmad]

Wow marmad, the thread that you started hit a new milestone! 100 pages, Congratulations! 

Well, congratulations go to all the members who've contributed here. And the length of the thread is a testament to the fact that Owon IS providing a product at a certain price point - and with particular features - that people still find desirable. 

I'm also disappointed with the progress in the firmware side, more so with unresolved bugs than the lack of new features. Owon's behavior in my opinion is counterproductive, but is their choice to decide where they want to go in the future. The main point I've attempted to make, is that in spite of the shortcomings, we don't all consider our Owon scopes to be totally manure. I'm still enthusiastic about the many things that I can do with my Owon DSO that were simply not possible with my old Tek CROs. I know that you now own a 70MHz Rigol DSO with very nice features. In my case, I already owned two 60MHz Tek CROs, so I wanted to get at least 100-200MHz for a new DSO. The SDS7102 offered 100MHz and was usable to 200MHz for a price I could afford. So I still think I did fine for my needs. But I do agree that Owon could do better, at least in popularity, if they would cater to user base needs and desires. There is nothing like word of mouth, in my opinion!

Sure, I agree. I'm all for Owon quashing bugs and improving hardware as their primary goal - just wish they would have thrown a slightly larger percentage of their efforts into adding a few new features (e.g. fine scale control).

[AndrejaKo]

And after check how OWONs customer service work, do you think that they will apply the warranty?
I doubt.

Well I have no doubts. My scope's first fan became noisy after few months of use and was very quickly replaced.

Another problem was with recent firmwares, my scope would freeze from time to time when booting. Owon and my distributor couldn't figure out what was wrong and replaced the main board. It's been working fine since then.

Also it's strange that you, who doesn't care about Owon at all, is spending so much energy hating Owon and spreading the hate. Can't you just forget about us and move on to threads about good scopes?

Also in some cases, Owon, with all of its problems, is the only option. For example in my country cheapest Tektronix or LeCroy scopes cost couple of thousands of Euros. CROs start at around 700€ (and that's for 70 Mhz ones). "Local" Rigol distributor is in Italy, which makes them uncompetitive. This environment combined with salaries makes it worthwhile to take time to work out Owon's quirks.

[Carrington]

Well I have no doubts. My scope's first fan became noisy after few months of use and was very quickly replaced.
Another problem was with recent firmwares, my scope would freeze from time to time when booting. Owon and my distributor couldn't figure out what was wrong and replaced the main board. It's been working fine since then.

Congratulations, All the best!

Also it's strange that you, who doesn't care about Owon at all, is spending so much energy hating Owon and spreading the hate. Can't you just forget about us and move on to threads about good scopes?

Hate? You are mistaken. 
I think a lack of respect, you're telling me I have to do! Really? I say: FREEDOM

Also in some cases, Owon, with all of its problems, is the only option. For example in my country cheapest Tektronix or LeCroy scopes cost couple of thousands of Euros. CROs start at around 700€ (and that's for 70 Mhz ones). "Local" Rigol distributor is in Italy, which makes them uncompetitive. This environment combined with salaries makes it worthwhile to take time to work out Owon's quirks.

I think there are more fish in the sea. 

[TomC]

Here is the latest revision of the schematic for my old PSU. Learning in detail how each component works is proving to be more challenging than I foresaw. So I'm still working on the theory of operation paper. So far I've found a few apparent blunders that may be helpful in quashing the GND noise issue. Specially in the snubber circuits. So I'll be posting my views and opinions on this soon.

[lemon]

Great work TomC, keep going in the same way! 

Can you give me the Version of the newer psu board? I am looking at your photos that you had upload but there isn't seem nothing!

[lemon]

Here is some last mods to my adapter Version 3.0

I have upload a video to see how is the real pattern of ground noise and how this changed at the time (it is taken from my mobile with 640X480 resolution).
The refresh rate of capture of samsung mobile is lower than real refresh rate of Owon. For this reason sometimes there is forward-reward movement of peaks at the left-right side of noise pattern.

The range of noise is 38-60mV peak to peak (Acquires Mode to Peak), with the most values btw 44-50mV.
This is not bad, if we think the marvelous 28-30mV of BBAAHHOO member with a dozen of heavy modifications.

I have attached the mods that I have done to the adapter board (attention this is Ver. 3.0). I haven't attached the mods on psu board, this followes the signs that has been marked at the post #1383 (a lot of smd decoupling capacitors).

[TomC]

Great work TomC, keep going in the same way! 

Can you give me the Version of the newer psu board? I am looking at your photos that you had upload but there isn't seem nothing!

There is no version number. I was wondering the same thing when I first got the board. Maybe the board is a prototype, I don't know! Very strange!

Good work on the mods, I watched the video and the noise seems pretty low.

I haven't done any changes on the old PSU yet. Still working purely on theory, maybe I'll be surprised at what I see when I power it up and look at some waveforms. But I don't want to get ahead of myself for now, I'm getting a little impatient though!

[lemon]

Very strange, really! A thumb down  for this to Owon.

(this adding latter) = TomC if you see the post of dgmoore78@yahoo.com (post 1331) measures 34mV peak to peak (serial =SN#SDS71021319xxx). This is stranger vs yours result. Probably the Owon has done some other changes (to adapter board of course) but there are no available until now...

You have a lot of time to investigate more the psu circuit. Who knows, maybe you find a smart solution for low emi radiation.
I am very curious about BBAAHHOO works. He took individual voltages from the psu board without needs the dc-dc adapter convertors that produce a lot of  noise.
Maybe the more sophisticated solution is the redesign of psu board with independed voltages.



 

[TomC]

Here is a partial draft of the Theory of Operation paper I've been preparing for my old PSU.

Keep in mind that I'm not an expert on SMPS, so although at this point I believe things work the way I explain them in this paper, I'm just learning myself. At this point, everything in this paper is theoretical, I haven't experimentally verified any of it. I plan to do that once I finish the theoretical research and complete the paper.

As always, any comments, disagreements, suggestions, etc. are welcome! I can use all the help I can get.

[lemon]

TomC you have done marvelous analysis of operational theory of circuit.
 
I haven't the appropriate knowledge to help you about this but for a quick reading that I done note your proposal to faster diodes and check of values to snubber circuit.

Really I'll waiting you to finished this great work!

[TomC]

This is a better quality photo of my old PSU board printed circuit side that can be used together with the previously posted schematic to explore the circuit topology. On the original you could clearly see all the component values, but I had to compress a little to post it here. So you may have to guess a little in some cases.

[TomC]

This is the matching component side photo for the previous post. I removed all the gook that the factory uses to prevent audible buzzing from the high frequency switching. I couldn't read some of the component labels because of it.

[TomC]

I am very curious about BBAAHHOO works. He took individual voltages from the psu board without needs the dc-dc adapter convertors that produce a lot of  noise.

Lemon, I've been reviewing BBAAHHOO posts, and I can't find where he derived other voltage sources from the PSU board. From what I see, it seems that all he did is add filtering to the existing voltage sources. Is there something that you see that I'm missing?

BBAAHHOO, can you clarify this? If you are using voltage sources other than the original, can you give us more details on how you did this?

[lemon]

For example look at the attachment photo of post 1465.
What is that he is doing here?
He removed all the dc-dc convertors U2, U13, U21 from adaptor board and drives the appropriate voltages from heavily modificate psu board. For this reason look at the schematics of post 1462. He draws the circuit that he uses for independent outputs of 3.3/5.5/6.8/-7.4 Volts
The result are very fine but the same result had the rf-loop with other way of modification and as said to my previous post, seems the same result have and Owon to the newer ocilloscopes.

[BBAAHHOO]

Hi to everyone. My new results. - From the network 18-22 Vpp, battery 12-18 Vpp. Reduced noise from the screen. Added capacitors on the conclusions of the LCD screen ( 0.08 nF which are used in many LCD screens). After this enhancement, there are some distortions on the monitor output.

All power DC-DC original. Added filter and transfer to another place.

[TomC]

I've been trying to download  BBAAHHOO's zip file from two different computers but all I get is html review of Owon sds... The log next two it says downloaded 2 times, so I don't know if there is a problem on my end or with the blog's download mechanism. Is any one else having this problem?

[Flash2light]

Author of the article.
https://www.eevblog.com/forum/testgear/review-of-owon-sds7102/?action=dlattach;attach=56620

Snubbers Using Standard Recovery Diodes.

Cheap and slow is not bad. 

Designing R2CD Snubbers Using Standard Recovery Diodes
http://www.intusoft.com/lit/Designing%20R2CD%20Snubbers%20Using%20Standard%20Recovery%20Diodes.pdf

[lemon]

I've been trying to download  BBAAHHOO's zip file from two different computers but all I get is html review of Owon sds... The log next two it says downloaded 2 times, so I don't know if there is a problem on my end or with the blog's download mechanism. Is any one else having this problem?

TomC, just I downloaded without problem, the files must had Russian characters because they translated automatically to Greek letters with numbers. He tells us that removed all the dc-dc convertors and put all of them in a new board with appropriate filtering... Am I right BBAAHHOO?

At your zip file you have enclosed a new photo with some mod to mainboard. Are these the capacitors that you said for lcd display? I can't understand what you have done, maybe it needs the original photo vs the mod photo.

[lemon]

BBAAHHOO looks the comparison of the attachment photo, the left is yours the right is factory original. What kind capacitors are they because you have bridged all of them with the first two parallel pins.

This is your mod for the lcd.
Your results are great!