Author Topic: REVIEW - Owon SDS7102 - A look at the SDS series from Owon  (Read 1315316 times)

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Offline kuson

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2350 on: February 28, 2014, 08:38:52 am »
Thanks very much for the fast reply TomC!  [ If you/Marmads come around Bangkok, Thailand, feel free to call me for local support -- free lunch! :>   ]

What would be the current Low-Noise mV peak to peak (Vp) that others are getting or that I should be getting?  How far should I be away from other power adapters/transformers (most are 220v AC to 12v DC) so that the noise does not effect my Oscilloscope?   

When I saw the noise I was getting I was alittle frustrated -- I tried measuring 12V battery's as well as 1.2V battery's  [AC Coupling mode] and I see quite the same noise, albeit slightly less Vp maybe 50-60 mVs.   So I suspect that I may have something internal that is differnt to the serial number, and now SMTZONE and Owon is helping to investigate.

Thanks again,
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2351 on: February 28, 2014, 05:22:11 pm »
Thanks very much for the fast reply TomC!  [ If you/Marmads come around Bangkok, Thailand, feel free to call me for local support -- free lunch! :>   ]

What would be the current Low-Noise mV peak to peak (Vp) that others are getting or that I should be getting?  How far should I be away from other power adapters/transformers (most are 220v AC to 12v DC) so that the noise does not effect my Oscilloscope?   

When I saw the noise I was getting I was alittle frustrated -- I tried measuring 12V battery's as well as 1.2V battery's  [AC Coupling mode] and I see quite the same noise, albeit slightly less Vp maybe 50-60 mVs.   So I suspect that I may have something internal that is differnt to the serial number, and now SMTZONE and Owon is helping to investigate.

Thanks again,
From what I've seen most get under 40mVs. The most troublesome power adapters are the ones that use SMPS like the ones for laptops. You can see a change in noise level as you get one of these close to the probe cable. To help rule out outside interference you can use ferrite cores on the probe cable, one at each end with the cable looped once if possible for extra inductance. Also keep the probes away from the scope's screen, as that produces a lot of radiation. I always keep ferrites on my probe cables so I don't have to worry that much about outside interference. I don't think that the noise level you are seeing is outrageous, but I would have expected a little less with a newer scope. Let us know what you find out! Good luck! :)
 

Offline lemon

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2352 on: March 01, 2014, 12:08:15 pm »
Hi to all members...

As TomC said,  your noise level isn't bad, but we would have expected a little less with a newer scope.
Ours scopes are older than yours and most of us, we have adapted the psu and adapter boards or change them with the new ones. You see my results with the new psu & adapter board at #2242 post.

I have a concern, if your scope probe cable was at fixed place or free on the table.

Kuson, please repeat the test like the attachment photo of #1330 post and give us the result.
 

Offline KindleFlame

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2353 on: March 10, 2014, 02:16:08 pm »
I found EDS102C/V on taobao:
http://item.taobao.com/item.htm?spm=a230r.1.14.23.1mbuPl&id=13859092514
It's seems to be the same as SDS7102V. Am I right?

Damn, I finally found the post where the guy managed to enable the language packs.

http://radiokot.ru/forum/viewtopic.php?p=1725552#p1725552

Now, does anyone speak russian?  |O
 

Offline kuson

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2354 on: March 10, 2014, 05:00:12 pm »
[RE-POST WITH PICTURES]

Hi Lemon, TomC,

Thanks for your posts!  Here is the results after coiling the cord as per your recommendations.

For CH1, the noise came down lower to ~60mv Vpp...... this same noise level also gets registered when I measure normal 1.2v or 6v DC batteries;   I went to do this at my garage, far away from any nearest wall-wart.   For CH2, I'm getting around 10mV.

I'm concerned about CH1 -- Does my oscilloscope be considered ok?  I've seen your posts with the modded components and it looks like the 10mVs, which is far better than what I'm getting.   I've emailed to SMTZONE and them to OWON and the quick and short reply is my oscilloscope is ok (which I'm not sure);  I've asked them what tests I can conduct further and there is NO REPLY whatsoever :(

Thank you so much again, TomC ,Lemon,
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2355 on: March 10, 2014, 10:01:16 pm »
[RE-POST WITH PICTURES]

Hi Lemon, TomC,

Thanks for your posts!  Here is the results after coiling the cord as per your recommendations.

For CH1, the noise came down lower to ~60mv Vpp...... this same noise level also gets registered when I measure normal 1.2v or 6v DC batteries;   I went to do this at my garage, far away from any nearest wall-wart.   For CH2, I'm getting around 10mV.

I'm concerned about CH1 -- Does my oscilloscope be considered ok?  I've seen your posts with the modded components and it looks like the 10mVs, which is far better than what I'm getting.   I've emailed to SMTZONE and them to OWON and the quick and short reply is my oscilloscope is ok (which I'm not sure);  I've asked them what tests I can conduct further and there is NO REPLY whatsoever :(

Thank you so much again, TomC ,Lemon,
It seems that you have Ch2 set to 10mV/div for the Ch2 test. That cuts down the bandwidth and makes the noise appear to be less. What do you get with Ch2 set to 50mV/div?

Edit:
After looking at your Ch2 photo magnified I think you have the scope's probe setting for ch2 set to X1. But since the probe itself is set to X10, you have to multiply the reading by 10. What you think is 10mVs is really 100mVs. As far as whether your scope is OK or not, I think it probably falls into the category of normal, but still a little noisier than average. To help rule out external noise, have you tried ferrites on the probes? I attached a photo so you can see what I mean.
« Last Edit: March 11, 2014, 01:53:50 am by TomC »
 

Offline lemon

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2356 on: March 11, 2014, 11:19:12 am »
Please, follow exactly the procedure. Keep the same schema of probe cable as you tested the last one.

For this reason, I quote the post #1330.

Very well!
The noise is low without any peaks.

The member "rf-loop" had suggested a method for this.

Procedure for measurent of Noise GND
----------------------------------------------------
Make a Calibration procedure as the notes says (look in manual).
Compensate the probe as manual described.
Change switch probe to 10x.
Do the same and the Probe Owon Menu (10X).
Connect probe to Probe Comp and GND wire to GND. Fix the cable of probe like the attachment photo.
Turn CH2 off.
CH1 to DC, 50mV/Div.
Push Trigger 50%
Set the Acquire Length to 1M and the Mode to Peak
Set the Horizontal speed to 100us
Set the measurement to Voltage peak to peak (Vp to Owon) and write the value.
 

Offline kuson

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2357 on: March 12, 2014, 05:18:04 pm »
TomC Lemon!

I have ordered the ferrite cores from Ebay :)

I have got the noise down abit to about 40mV Vp for both channels 1 and 2-- perhaps it was about the winding of the cables and quite hopeful the ferrites would help :)

Will update when I get them in 2 weeks :) Thanks so much for your feedbacks-- really appreciate them :)
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2358 on: March 12, 2014, 06:54:26 pm »
TomC Lemon!

I have ordered the ferrite cores from Ebay :)

I have got the noise down abit to about 40mV Vp for both channels 1 and 2-- perhaps it was about the winding of the cables and quite hopeful the ferrites would help :)

Will update when I get them in 2 weeks :) Thanks so much for your feedbacks-- really appreciate them :)
That looks good! :-+
What you see now is in the average range. This amount of noise shouldn't impair readings of low level signals when you use full bandwidth, which is the major objection to excessive ground noise.

The ferrites will help keep common mode noise at bay, which will result in a more consistent experience in different environments. Without the ferrites, the probe cables will pick up more common mode noise from the environment, e.g. wall warts, other electronic equipment, radio/TV stations, fluorescent lights, etc., and because you are using a long ground wire, the common mode noise is changed into differential mode noise which you then see on the scope's screen.

For cases where you want to see the best possible representation of the true signal it is best to use the shortest ground lead you can possibly get away with, or better yet, use a probe test point. This will prevent the common mode noise from being changed into differential mode noise. Although the common mode noise will still be present, it will be invisible to the scope's input amps and therefore you won't see it on the screen.
« Last Edit: March 12, 2014, 06:57:45 pm by TomC »
 

Offline lemon

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2359 on: March 13, 2014, 08:02:24 pm »
Kuson, you are OK.  :-+

Quote from: TomC
...For cases where you want to see the best possible representation of the true signal it is best to use the shortest ground lead you can possibly get away with, or better yet, use a probe test point. This will prevent the common mode noise from being changed into differential mode noise. Although the common mode noise will still be present, it will be invisible to the scope's input amps and therefore you won't see it on the screen...

I took the spiral of this rca



and done some short ground clips like this (in various sizes) :
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2360 on: March 13, 2014, 08:38:33 pm »
Great idea! :-+
Thanks for the pics.
 

Offline rman_nl

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2361 on: April 01, 2014, 10:51:05 am »
TomC Lemon!

I have ordered the ferrite cores from Ebay :)

I have got the noise down abit to about 40mV Vp for both channels 1 and 2-- perhaps it was about the winding of the cables and quite hopeful the ferrites would help :)

Will update when I get them in 2 weeks :) Thanks so much for your feedbacks-- really appreciate them :)

Plz can u tell us which ferrite you have orderded? Eaby link would be nice.
 

Offline kuson

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2362 on: April 02, 2014, 01:54:07 am »
RmanNL,

 I bought http://pages.ebay.com/link/?nav=item.view&id=360479080355  it was larger than the probe cables but fit the tapered ends of the cables. Not sure if these were supposed to fit snug on the cables themselves!

Sorry Lemo TomC I tried to upload pictures from my mobile device but thw pix was over 2MB... I got 34-38mV Vp as a result of putting 2 ferrous cores on each side ... the probe side and the plug side-- will upload to you later but many thanks and tell me when you come to TH :)
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2363 on: April 02, 2014, 03:54:42 am »
RmanNL,

 I bought http://pages.ebay.com/link/?nav=item.view&id=360479080355  it was larger than the probe cables but fit the tapered ends of the cables. Not sure if these were supposed to fit snug on the cables themselves!

Sorry Lemo TomC I tried to upload pictures from my mobile device but thw pix was over 2MB... I got 34-38mV Vp as a result of putting 2 ferrous cores on each side ... the probe side and the plug side-- will upload to you later but many thanks and tell me when you come to TH :)
Very good results! :-+

I see you got 7mm ferrites, the ones I'm currently using are 8mm. They don't need to be snug on the cable. However, what I recommend, which I'm not sure if you are doing yet, is to loop the cable once around the ferrite on each end. This way the cable goes twice through the ferrite on each end and you get twice the inductance. If you haven't done this yet, give it a try and see if there is any improvement.

Good luck! :)
 

Offline kuson

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2364 on: April 04, 2014, 02:03:02 am »
Dear TomC,

From Original Thread: Owon SDS7102 (page 158) Ground Noise on Owons purchased on Jan 2014 (New Manufacturing Batch) --> RESOLVED THANKS TO TOMC, LEMON

Here are the pictures at last! I tried the loop at the Ferrous Cores on each side of the ProbeCable (as pictured, not sure if I did it right ) and now I have the noise to 14-15mV Vpeak!     

Thanks Again TomC, Lemon :>   Now I can bravely face all the New Stuff to learn with the help of the Oscilloscope!
What are good stuff to poke around with this oscilloscope to learn the different kinds of readings? (Low Priority Question) :>


 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2365 on: April 04, 2014, 02:43:44 am »
Looks good! :-+

Don't be discouraged, but your real noise reading is probably a little higher than you think. I noticed that you are using 20mV/div. This restricts the bandwidth and as a result some of the higher frequency noise is filtered before it reaches the screen. To get your true noise level you need to use 50mV/div.

Best of luck! :)
 

Offline rman_nl

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2366 on: April 04, 2014, 05:26:05 pm »
The test: It is 46 mV Vpp.

update: Exactly after 21:00 its
12 -14 mV Vpp  --- acquire peakdetect
8 mV Vpp          ---acquire Average 4




Owon: DS7102V
serieno: SDS71021407522
version: 3.5
« Last Edit: April 04, 2014, 08:27:04 pm by rman_nl »
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2367 on: April 04, 2014, 09:22:51 pm »
The test: It is 46 mV Vpp.

update: Exactly after 21:00 its
12 -14 mV Vpp  --- acquire peakdetect
8 mV Vpp          ---acquire Average 4




Owon: DS7102V
serieno: SDS71021407522
version: 3.5

What I see on the screen looks very good! :-+

About 25mVpp on average except for the larger pulse in the center of the screen.

I'm not sure what you mean by "Exactly after 21:00". But from what I can see you have the kind of normal results we expect from newer scopes!
 

Offline rman_nl

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2368 on: April 05, 2014, 05:12:15 am »
The test: It is 46 mV Vpp.

update: Exactly after 21:00 its
12 -14 mV Vpp  --- acquire peakdetect
8 mV Vpp          ---acquire Average 4




Owon: DS7102V
serieno: SDS71021407522
version: 3.5

What I see on the screen looks very good! :-+

About 25mVpp on average except for the larger pulse in the center of the screen.

I'm not sure what you mean by "Exactly after 21:00". But from what I can see you have the kind of normal results we expect from newer scopes!

9  o'clock am
its now 7:00 pm
and the Vpp = 18- 28 mV  Vpp acquire peak detect
                        8.000mV   Vpp acquire  Average 
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2369 on: April 05, 2014, 06:29:40 am »
If the noise changes like clockwork at certain times, I doubt that it's something in the scope that's causing that. I would suspect external interference of some sort. Perhaps someone in the neighborhood turning on a transmitter, generator, or other type of equipment that generates RF. Have you tried ferrites on the probe cables to see if the effect is less. In any case, I think that the amount of noise that you are experiencing is very small and shouldn't interfere when viewing low level signals. Let us know if you find the source!
 

Offline lemon

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2370 on: April 05, 2014, 07:48:39 pm »
The test: It is 46 mV Vpp.

update: Exactly after 21:00 its
12 -14 mV Vpp  --- acquire peakdetect
8 mV Vpp          ---acquire Average 4

Owon: DS7102V
serieno: SDS71021407522
version: 3.5

Very good results!
I see a new firmware 3.5!
At Owon's site the fw is 3.3 still!

My opinion for that oscilloscope is remaining the same. Good hardware, average software. Unfortunately, the chinese Owon doesn't developed the software. Many of us, send to them some suggestions for the fw but Owon was deaf!
I see at your fw (3.5) that the Vpp appears Vp still!!   :palm:
 

Offline Sarasir

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2371 on: May 24, 2014, 12:17:12 pm »
Hi everybody,

finally I found you after some time searching the web for OWON users.
I bought a SDS 9302 a while ago and when testing it soon dicovered the noise problem.
At first couldn't believe it and wrote to OWON but they did not answer.
After opening the thing and further testing soon I located the problem. It's as you also know - I haven't yet read through the entire post here so forgive me if I repeat things already posted - the power supply, the main one but also the distributed little switchers as i found out later.
I couldn't stop my self and started to denoise the main PS. After that lots of spikes where still present and I contacted the seller of my OWON (Präzitronik Hennig / Messgeräte Chemnitz) and he send my mail again to OWON and this time they answered that they are already working on the problem and also send the service manual I had asked for.

So, meanwhile I was digging myself deeper and deeper into this Scope and finally realized what they did. IT'S UNBELIEVABLE!!!

I think I have to say now that I worked with Tektronix for about 10 years as a service engineer her in Germany. Now I'm retired since many years but still do electronics a lot .

Yeah, back to the OWON, Step by Step I removed the little Buck converters from the interface PCB and even one from the main board - AGAIN UNBELIEVABlE TO PUT AN UNSHIELDED HIGH FREQUENCY SWITCHER ON THE SAME PCB WHERE THE INPUT CIRCUIT IS!

Next thing was to give the input circuit a decent shielding soldered tight around the input circuit on the main PCB and with the covers screwed on for to have access still.

I'm not through with all the switchers yet. One is still left thats the one for the Display, not the backlight. I couldn't find any IC datasheet for this one and also the one that provides the power to the LED backlight. Perhaps one of you found that out and can post it here maybe again for me until I heve read through all pages.

Will also check the display maker, Maybe there is some app note with these switchers.

I have the schemes of what I did so far, could reduce the noise remarkably, and if you are interested can also post some photos of what I have done.

For the moment I will stop and wait for what you say.

Thanks for reading + best wishes.

Sarasir
 
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2372 on: May 24, 2014, 01:50:52 pm »
Very interested in what you have done so far, by all means, post photos and schematics!  :-+
I own an SDS7102 and have replaced the main PS board and use some ferrites internally and on the probes to reduce noise. Now in the less than 30mVpp range. :)
 

Offline Sarasir

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2373 on: May 25, 2014, 01:21:15 am »
here my first steps:

you can see the tin box I made for the main SMPS and some filtering. Also on the back side of the PCB I cut the second heat sink free and connected it to output ground so it serves as a shield as well (ONLY POSSIBLE IF A FULLY ISOLATED SCHOTTKY RECTIFIER IS USED!!!!! In my model it was so).

At that stage I still was so naive to believe that by doing this mod the problem would be solved!
Therfore I also replaced the knobs as you can see. Pardon me, but the original ones are just a pain in the ass.

But that ment also that I couldn't go back and return the thing because to take the original ones off  without somehow damaging the 'potentiometers' - they where absolutely tight - I decided to cut them off carefully.

I also had to turn around the mains input mudule to give more place to the tin box.

This Mod reduced the noise a bit but there was still too much....

And be aware, that I'm not through yet with the little converters so no final results now to tell only that the noise got lesser and lesser with each step I made.

To be continued ....



 

Offline Sarasir

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #2374 on: May 25, 2014, 01:52:33 am »
sorry, by getting all together and taking and posting the pics I forgot to reply to you:

Yes, 30mV, better than nothing of course but what means that for a scope at 2mV or 5mV input/division sensitivity as on mine - probably yours as well? It means, in my view that you can not use it when you have to check  e.g. a phono pramp and what else low level circuit... And these spikes also make triggering practically impossible at low levels.

I can not live with that. A scope must be clean otherwise you never know is it the scope or your DUT.

Also had the idea to replace the main SMPS even with a conventional transformer design but only untill I discovered all the liittle converters.

I think the final solution will be to take all little switchers off from the PCBs and put them in one tight tin box.

But well see - And somhow I really love this little bastard. Aside from above probs it's designed really nicely and cute.

Men need challenge I would say...
 


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