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

[Sarasir]

Hi TomC,

it's not so easy as I thought. The long wires bring other problems I have not thought so much about yet. E.g. the + 1.9 supply must be very stiff. I think it is for the CPU/controller and has to supply around 0.8A. So far, with additional capacitors on the main PCB it works but after a while the Owon hangs up in a way and there is lots of spikes on the scope side of the supply wires I can see now coming from the main PCB not from the supply. Next I will stiffen the + 3.3 and try to get rid of the spikes from the main PSU or better to say first to find out where they are comming from exactly.
I should have known as on a PC main board the processor supply is always close to the processor. Of course a PC CPU draws more power but in a way the basic rules are the same I would say.
Another thought is that this hanging up problem might be a defective chip or soldering because it goes along with the main PCB heating up a bit. Somtimes it goes away by itself. and comes back after a while. Turning the power off and on the Owon works again, so it's not so much a heat problem. Have to check that again watching the average time it take until hang up if it's cold and if it's already warmed up.

And have trouble with my teeth. Got 4 implants recently and yesterdy 2 had to be taken out again. Running to the dentist about every third day since weeks takes time and I feel a bit stressed. But what can you do, shit happens....

[TomC]

for same pay ( i can pay 800$ to 850$)  i want buy the best , i say need 70 to 100MHZ and 1 to 2Gs for sampling.
and i want know which is better for same cost ?
thanks again
i read datasheet of SDS2000(SDS2072 ) and DS2000A(DS2072 ) , and i think SDS better .
SDS7102 good too for me .
and i really Helpless .
regards

In my opinion, the Rigol 2072 and the Siglent 2072 are pretty much in the same class. It boils down to the specific features that you value the most. The Siglent seems to have a richer feature set, but it's newer and has a better chance of having more unresolved bugs. The Rigol has been around a while longer, and from what I hear many bugs have been already resolved. Also, there are a number of users that have managed to hack it and unlock extra cost options for free, if you are interested in that, Btw, personally I'm not. The Owon SDS7102 can't touch some of the features available in the Rigol and Siglent, but is cheaper, and it has 100MHz+ bandwidth without hacking, so if you are happy with the feature limitations is a good buy. That's about the best I can do to help you decide, but ultimately is up to you. I think you'll probably be happy with any one of these scopes!

[TomC]

Hi TomC,

it's not so easy as I thought. The long wires bring other problems I have not thought so much about yet. E.g. the + 1.9 supply must be very stiff. I think it is for the CPU/controller and has to supply around 0.8A. So far, with additional capacitors on the main PCB it works but after a while the Owon hangs up in a way and there is lots of spikes on the scope side of the supply wires I can see now coming from the main PCB not from the supply. Next I will stiffen the + 3.3 and try to get rid of the spikes from the main PSU or better to say first to find out where they are comming from exactly.
I should have known as on a PC main board the processor supply is always close to the processor. Of course a PC CPU draws more power but in a way the basic rules are the same I would say.
Another thought is that this hanging up problem might be a defective chip or soldering because it goes along with the main PCB heating up a bit. Somtimes it goes away by itself. and comes back after a while. Turning the power off and on the Owon works again, so it's not so much a heat problem. Have to check that again watching the average time it take until hang up if it's cold and if it's already warmed up.

And have trouble with my teeth. Got 4 implants recently and yesterdy 2 had to be taken out again. Running to the dentist about every third day since weeks takes time and I feel a bit stressed. But what can you do, shit happens....

Wow, seems like you have your hands full! But you have done many modifications at once, so some hiccups are to be expected! Hard to tell if the hang-ups are related, but noise in the processor supply would definitely be a suspect in my opinion.

As far as the main PSU, I found most of the noise was coming from the -7.6V switcher, particularly L2. There also was a little bit of noise coming from the 8.4V switcher, particularly from TR1 (transformer). I don't know how you plan to handle that, I replaced L2 with a toroid and put a belly strap on TR1. That got rid of most of the noise in my case.

Hope everything settles down and improves with your dental treatment! I'm lucky enough to be missing only two back teeth at my age. But I'm a dental hygiene fanatic that brushes, flosses, and water picks three times a day and never snacks between meals. Maybe that has something to do with it, or maybe is just good luck.

[mohandes]

thank Tom
my friend have 500$ , and i tell him SD7102 is best ? i say right to him 
regards

[TomC]

If it was me, I'd still choose the SDS7102 if I only had $500 to spend!

[Viktor]

I have just succesfully flashed firmware v3.8 to my SDS7102V. I'm installing Owon's PC software now.
You can find Rigol DS2072 directly from China on taobao. Price is from 740 USD without shipping. SDS7102 is from ~ 290 USD without shipping.

[mohandes]

I have just succesfully flashed firmware v3.8 to my SDS7102V. I'm installing Owon's PC software now.
You can find Rigol DS2072 directly from China on taobao. Price is from 740 USD without shipping. SDS7102 is from ~ 290 USD without shipping.

thanks
but in this site write 940$ !!!!!!!!!!

[Sarasir]

Hi TomC,

built an extension for to be able to work on the main PCB. Without it's also practically impossible to calibrate the input you certainly know as well. I thougt that the hangups might be erratic oscillation in the input circuitry, at least it feels like that because the whole screen fills with distorted high frequency and the machine does not really hang but gets very slow in reacting. And when it goes away it looks like if you are working on an amplifier which oscillates and by bending a wire the self oscillation collapses.

Enlarging the input shielding might be the initial reason. I thought that would give less input capacitance and there was enough space especially on the rear side.

Will see tomorrow, and meanwhile some pics below.

[rf-loop]

Sorry Sarasir but I do not understand anything what you have done with analog front end and why.

I have inspected many versions of Owon analog front and I have not finded any reason for modify shieldings etc (exept first version where BNC's was not at all instelled to PCB). Front end is one of best front end in this class if look example its noise level and frequency band. Also Owon input capacitance is originally typically quite low. It was this layout version we measure it by VNA and it was "around" 8pF (under Owon specs). There is not any reason for try get it more low. Tektronix 2465 have 15pF and they really know what they do. Same in old HP, in this case 8pF in 500MHz scope and agen in one Tektronix 500MHz it is 10pF. (nominal +/- something)

In original condition input circuits do not picup any markable amount of internal or external noise around it. Close differential input (50ohm terminator is enough and zero z do not make big difference) and you know it after you measure noise figure and repeat it with open differential input (example using 50ohm terminator without center tab connected) and measure noise figure (not only level). In this case differential input other pole is exactly this part of BNC outer terminal what is just in position where is its inner terminal (connection point). This is reference point and nothing else  if think oscilloscope input.
Compare this noise figure with Agilent, Tektronix, or even Rigol better models than 1052.

Now you tell that your input stage oscillate? (really? )
You have changed parasitic components?

Just return all  exatly as it was after factory (I mean only front end - but overall nice experimental work specially for reduce SMPS generated RF noises) and you have reasonable good front end well comparable with Agilent and Tektronix much more expensive models. In worst case, modifying shielding there may lead even worse result even if it looks like "better" physically with eye. (it is due to fact that where these noise currents flow) (this is not for Owon but sometimes example changing RF field "GND" connection points may lead worse situation because it change noise current road. It is good to imagine that there is not common homogenous GND! Every single point in GND is different where ever it is. DC and low audio is different and  1MHz is quite easy but 1GHz is more difficult and 1THz is just magic.

In Owon - just analog front and also ADC is very good. Other good part is very good quality TFT.

added sidenote:
 it looks that your front end version is version what can not fully adjust without separating front panel board and main board.  Some version can adjust more easy.

[onlooker]

Sorry for side track a little. Could anyone share the tx file if your SN is one of the SNs below:

SDS71021122xxx, SDS71021127xxx, SDS71021137xxx, SDS71021143xxx, SDS71021149xxx, SDS71021152xxx, SDS71021153xxx, SDS71021203xxx.

I accidently overwritten the tx file on my machine when playing with "launch.exe usbpatch".  Apparently,  "launch.exe usbpatch" is a dangouse combination. It will download the file named "bundles" to the device with brutal force and without checking its contents. It so happened, one of the patch comes with a "bundles" file for some other HW platform and it had a tx file, and I played with it without knowing.

I have since re-downloaded the correct fw (OS_H6 for SDS7102) using the same "launch.exe usbpatch" option. The machine  is working again. But I am unable to recover a same or similar tx file. I have tried recreate a tx file based on those in txs.zip. But, those are not for 7102 or not for the HW version 6 (as in OS-H6). I also tried on screen cal adjustments by activating the switch in the tx file. Many things can be caled, but not all of them. Especially the DC trig level mismatchs a lot.

I understand the cal data in the tx file is probably per machine. What I need is an example tx file (clear text or encrypted) for HW version 6 (SNs are listed above) of sds7102 to work from.

[TomC]

Hi TomC,

built an extension for to be able to work on the main PCB. Without it's also practically impossible to calibrate the input you certainly know as well. I thougt that the hangups might be erratic oscillation in the input circuitry, at least it feels like that because the whole screen fills with distorted high frequency and the machine does not really hang but gets very slow in reacting. And when it goes away it looks like if you are working on an amplifier which oscillates and by bending a wire the self oscillation collapses.

Enlarging the input shielding might be the initial reason. I thought that would give less input capacitance and there was enough space especially on the rear side.

Will see tomorrow, and meanwhile some pics below.

Hi Sarasir,

It's obvious from the pics that you put a lot of effort on the front end shielding, and the craftsmanship looks excellent! However, I agree that this may have something to do with the hang-ups. If it was me, I would consider doing what rf-loop suggests and return the shielding configuration back to factory condition, at least as a troubleshooting step. If that successfully corrected the hang-up symptoms, I would concentrate on the other part of the project and get rid of the noise produced by the switchers first. Then, if necessary, I would tackle the front end shielding again.

[Sarasir]

Hi rf-loop + TomC,

of course I noticed that the input noise of the Owon is very low and 10 pf input capacitance is also pretty low compared to my old Tek 475A with 20 pF.

I increased the distance to the PCB of the front and back shields by alltogether about 6mm. That should not decrease the input capacitance very much but might give me also the option to replace the ceramic AC coupling C with a decent one but don't know yet if a Tek made I have a few will fit in.

And there is also the thought to add a teflon variable C (also Tek made) by which you are able to calibrate the input capacitance. For this I would need a little headroom for to arrive finally at 10pF again.

But nothing decided yet, just providing options. You know there was space and why not use it.

And to the shield itself. After taking a first look at the input section I noticed that the shields where soldered only at three points to the PCB, an absolutely no go in my opinion.

If you had worked in the Tek lab for 10 years and knew all the machines you also know that circuits like this have to be in a closed shielding cage, no doubt.  Nothing goes in and out except  the signals that are supposed to.

Of course I could have soldered the original shield all around but with the consequence of not beeing able to open it up again without straining or even killing the PCB, should there be some work to do inside.

This input cage in itself is practically free of differential digital noise and consequently therefore is the reference point for the whole machine. Any noise that is radiated from other points of the machine to the environment will make that point radiating noise as well because the radiation loop has to close as it's true for any transmitter. To minimize or even kill that you 'just' have to catch all radiated noise and bring it back to this reference point internally. Then there will be no more noise potential on the BNCs to be seen anymore from the outside.

Of course as you already pointed out all noise sources (power switchers) should be minimized locally first, but then, what will you do with the noise radiated by the digital circuitry of the main PCB? The only way I can see is to first bring in the cleaned supply currents to the main PCB to a point as near as possible to the input cage for the make sure there is as little as possible voltage drop caused by the digital circuitry noticable to the input cage, and to bring back the radiated noise from the digital circuitry also to the input cage for closing the emission loop(s).

Then, in theory the Owon should be clean.

But I know in practice often you will come across problems you haven't seen before but you know 300 MHz is not too much to handle. Thanks God I havent bought a 1GHz or even higher scope from Owon. Saw a Tek 33GHz scope recently....

Hi TomC,

there is no way to go back to the original state with the shielding. Too much work, too much risk, and to increase the stray capacitances between the input circuit and shield again is easy once I'm able to work on it and to see any results right away. That's why the extension...

[TomC]

This is the sequel to post #2472:

https://www.eevblog.com/forum/testgear/review-of-owon-sds7102/msg460398/#msg460398

I recently received the 200MHz Hantek PP-200 probes I ordered from Amazon. To the limit of my RF generator (110MHz), the response of these probes is nearly identical to the 100MHz Owon T5100 probes that came with my SDS7102. This leads me to believe that the PP-200 probes at least qualify as 100MHz probes. I don't have access to the test equipment required to accurately further asses the response of these probes. However, I did conduct a few other experiments.

First I tried a homebrew diode frequency doubler attached to the output of my RF generator. This allowed me to check the response to nearly 200MHz, but with very low level signals (<50mVpp), due to the inherent losses associated with this type of doubling circuit. With one probe at a time connected to the output of the doubler, the T5100 probes produced a larger amplitude signal than the PP-200 probes. However, with a T5100 and a PP-200 probe connected simultaneously to the doubler the signal amplitude was nearly identical. Since the PP-200 probes have a larger input capacitance than the T5100 probes, I believe this effect was due to higher signal loading when the PP-200 probe was connected to the frequency doubler by itself.

Still, this test doesn't give me conclusive evidence of the response of either set of probes, just that their response is similar at up to 200MHz. It could be that the T5100s are really much better than 100MHz probes, or that the PP-200s are just 100MHz probes.

I plan to do some additional experiments, and I'll report any interesting findings that materialize. In the mean time, if anyone has tested the response of the Owon T5100 probes with appropriate equipment, I would very much appreciate it if they share their findings!

[TomC]

Hi Sarasir,

I get where you are coming from! Keep us posted, I find what you are doing very interesting!

[rf-loop]

Hi Sarasir,

I get where you are coming from! Keep us posted, I find what you are doing very interesting!

+1
Very interesting!

[Sarasir]

Yes TomC and rf-loop,

thanks a lot but also have to add that it was you guys here who contributed their knowledge and experience as well on the way to develope a pretty clear picture of the circumstances and possible solutions so far I would say.  With the Owon at first I had just lots of nebulous thoughts and started to remember what I had learned the time with Tek. You know in my personal interest I'm just an audio man and yes, also a devoted and experienced trouble shooter but after I've left Tek in fall of 1987 I didn't care so much about RF except that practically in every field nowadays you have to deal with digital components clocked by RF frequencies...

Just let me put it like this, only with the right partners you can reach the highest point!

[Sarasir]

Hi guys,

after above doodle doodle - sorry, but you should know I'm really happy to be able to discuss with you here - reality came back. During bringing all supply lines directly to the main PCB the erratic display or hang ups didn't go away at all anymore. And after getting me the datasheet of the A/D converter (MXT2815 supplied by the the +1.9V switcher) and studying it a bit (all in chinese, let Google translate it!) I had to understand that this chip is a bit demanding regarding the power supply. It has a build in power down routine and as far as I understood doesn't  like too big filter capacitors on it's supply lines - 100uF says the sheet I understood so far - and I put much more. Didn't get through yesterday but have a certain feeling...

Anyways I'm  thinking about getting me a second SDS 9302 as a backup and test rig. That's always good practise.

[TomC]

Hi Sarasir,

The Google translation is awful, but if I understood right, it says that a 150mV overvoltage or voltage spike in the supply line can damage the chip. If that's correct, this thing is super sensitive. But you would think that extra capacitors would decrease the chance of a spike, so maybe the problem is reversible. Let's hope that's the case anyway!

[rf-loop]

This is also useful to read
http://www.ti.com/product/adc08d1520

Do not ask if it is same or not.  

But useful to read.

(note with pin numbers. It is typical that RuiFeng add 2+2  N.C. pins to every corner)

[TomC]

It sure looks similar, same warning about the 150mV overvoltage!

[Sarasir]

Hi TomC + rf-loop,

rearranged the common/ground wires yesterday and it was working again - thanks God! But have to give it a little more voltage later today as there is a voltage drop due to the long wires I have put in between all PSUs and the main PCB. Only 1.85V arrive at the MXT2815. It seems to consume a bit more than what the sheet says 'cause I have tested before with a resistive load and it was precisely 1.9V.

Thanks a lot for the TI link + information. Seems that it's quite similar to the RuiFeng - reading the description briefly at least....

Spikes on the supply lines are quite low now except for both display supplies which are still pretty dirty. Also the display signal lines I have not really looked at yet.  Probably shielding and cores right where they leave the main PCB I can see so far.

I should be able to unplug the adapter PCB with the display ribbon alltogether without problem now as no vital function for the main PCB is located there anymore but haven't tried yet (then using the VGA to monitor)

The problem with the display circuitry supply is to keep up with the power up timing what should be no problem at all as it draws not much amps so it just has to be redesigned carefully.

Don't know yet exactly what to do with the backlight supply switcher as it's output capacitor is limited to 10uF max because of the current regulation loop. Replacing the original electrolytic with tantalum and/or ceramic turned out to be not enough and also did not add much inductivity for not to dephase the loop. Probably have to redesign this completely. Perhaps you have found a solution already rf-loop?

rf-loop, have you replaced the ADC once yet and can you buy from RuiFeng? I mean just in case for to have a back up. Also thought already to even get me a second Owon or a spare main PCB at least.

(Of most of my tools I have more than 1 device of the same type and lots of spare parts for not to get stuck during some work should anything break down. More than 30 Tek TM503 plug ins I have  build by myself when I was with Tek, all from spare parts! They liked that inofficially because it's the best training programm at all. We knew the machines down to the last screw and wire. Quite some of the technicians back then had their private side projects manufactoring quietly for the home lab)

Later I will check further and already have made some pics of a working Owon in exploded view...

[TomC]

Hi Sarasir,

Sounds like you are making fine progress! I don't have much to add this time so for now I just want to cheer you on!

[Sarasir]

Hi TomC,

no, again in the shit. It stopped again today. Think I have to go back to the power lines and check all through. There are still strong spikes. Just tested briefly on a good point yesterday and thought thats it.  All too much improvised at the moment and I'm not sure yet if the ADC has gotten a scar or not. Tinkered on the switcher a bit to adjust it to exactly to 1.9 (searching a little container full of SMDs for the right resistor can take half a day sometimes)

Some times I'm a bit too easy and want a quick result. But also had no idea that these chips are so sensitive. Feels like in the old days - remember Reticon BBD lines?

So back to step by step.... 

And have to read through the ADC sheet. Now the problem is no trace at all on the display and allways 'Ready' mode but the knobs do move their respective indicators... And when touching Owons ground on certain points with the 475A's probe ground lead the brightness steps through. So sometimes it even shows some humor..

You lucky one, tomorrow to the dentist again. Another disaster perhaps.

But worked on a good and hot piece of music today just to say something positive.

And on every cloud there is a silver lining.....

[TomC]

Hi TomC,

no, again in the shit. It stopped again today. Think I have to go back to the power lines and check all through. There are still strong spikes. Just tested briefly on a good point yesterday and thought thats it.  All too much improvised at the moment and I'm not sure yet if the ADC has gotten a scar or not. Tinkered on the switcher a bit to adjust it to exactly to 1.9 (searching a little container full of SMDs for the right resistor can take half a day sometimes)

Some times I'm a bit too easy and want a quick result. But also had no idea that these chips are so sensitive. Feels like in the old days - remember Reticon BBD lines?

So back to step by step.... 

And have to read through the ADC sheet. Now the problem is no trace at all on the display and allways 'Ready' mode but the knobs do move their respective indicators... And when touching Owons ground on certain points with the 475A's probe ground lead the brightness steps through. So sometimes it even shows some humor..

You lucky one, tomorrow to the dentist again. Another disaster perhaps.

But worked on a good and hot piece of music today just to say something positive.

And on every cloud there is a silver lining.....

Sorry to hear that!

I think it's possible that the symptom, always in ready state, may indicate that the ADC is not providing output data and as a result there is no trigger. Just wondering, does the scope produce a trace if you force the trigger? Hope is just a problem with the supply and not a damaged ADC!

Never heard of Reticon BBD lines until now! In case someone else is curios, here is a link that seems to explain how they work.

http://mysite.du.edu/~etuttle/electron/elect39.htm

Good luck at the dentist!

[Skimask]

Has anybody else gotten the Owon PC side software to work under Win7 Home Premium?
I read the help file, did the dance as suggested as far as turning on "Test Mode", etc.
No dice...