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

[Carrington]

Your mystery is like "Mitos of Ariadnes" (from Greek Mythology) same psu, identical adapter but the noise is differente, but remaining the answer of Flash2light what is marking of U2 in ver. 3.3. Probably, there is a difference there...

Well that's not too bad, I'll be more scared to look around for the answer if it resembled the story of Medusa, it wouldn't be cool turning to stone.

...

Tomc: Is the difference between yours and these very marked?

[Carrington]

Carrington about BW, you know (I think) the works of rf-loop, he has show us that this oscilloscope has over 200MHz bandwidth.

Yes I've seen it. Just send the appropriate command to the LMH6518 is in the input stage and you will have much more BW.

If I remember well you have additional the Rigol 2000 Series, I think that is one category over than SDS7102 and it is not fair to compare the two of them. About Rigol DS1052 or DS1102 that is the competition.

I'm not totally agree. Not so simple...

But if I remember well, the noise of SDS at full BW (5mV) is under 1mV. At the beginning when the noise gnd is very high (160-200mV) I couldn't to examine a signal with a few mV, it was full with artifacts and not stable - only with my old analoge Hameg I could.
Today with my mods (I have a noise gnd 40-55mV peak to peak) there is no any difference between Hameg and Owon in signals with a few mV, very stable and clearly.

I'm not complaining about this: "the noise of SDS at full BW (5mV) is under 1mV". This is acceptable. 
This is what bothers me: "when the noise gnd is very high (160-200mV)". Or "a noise gnd 40-55mV peak to peak".

[TomC]

Your mystery is like "Mitos of Ariadnes" (from Greek Mythology) same psu, identical adapter but the noise is differente, but remaining the answer of Flash2light what is marking of U2 in ver. 3.3. Probably, there is a difference there...

Well that's not too bad, I'll be more scared to look around for the answer if it resembled the story of Medusa, it wouldn't be cool turning to stone.

...

Tomc: Is the difference between yours and these very marked?

I get 60-70mVpp, which is better than what I had before (about 150mVpp). The disappointing part is that with the old PSU board, after adding some ferrites to the interconnecting cables, I had as good or better results than with the new PSU. However, as it is now, I can work a lot better with low level signals at full bandwidth. For example, I can easily trigger on a 50mVpp signal. When I had 150mVpp noise that was impossible unless I used the short ground clip.

[Flash2light]

Your mystery is like "Mitos of Ariadnes" (from Greek Mythology) same psu, identical adapter but the noise is differente, but remaining the answer of Flash2light what is marking of U2 in ver. 3.3. Probably, there is a difference there...

Well that's not too bad, I'll be more scared to look around for the answer if it resembled the story of Medusa, it wouldn't be cool turning to stone.

There are a couple of things I've been thinking about. I took a real good look at my new PSU board and discovered that one of the new decoupling capacitors is probably missing. There is no capacitor where C23 is supposed to be. C23 is supposed to be at the end of the adapter board connector. I see glue residue, as if the component was there but fell off during the soldering process. However, I don't think this would cause such a big difference in noise by itself.

Flash2light, can you tell me if this capacitor is present on your PSU board?

The other thing I've been thinking about is that I don't have the battery option. With a battery installed you have additional filtering for the 8.4V supply. The battery itself can act as a super capacitor. I don't know for sure if the results from dgmoore78@yahoo.com and Flash2light were obtained with the optional battery installed.

dgmoore78@yahoo.com and Flash2light, can you clarify this, and if possible, if your test was done with the battery installed, can you do the test again without the battery?

C23 has been removed.

Noise measured without the battery.

Battery measured noise is nearly the same.

If a test lead is straight. The noise increases. "The use of the battery 40mV" picture!


"if test lead move close to the psu or display. noise will increase."

[lemon]

It is known that if you straight the cable of probe you'll catch everything because the cable of probe will work like antenna and the noise will increased.

For this reason and for comparison reasons, we have suggest to all member to make the measurement having 2 cycles of cable fixed on the table.
In other case there will be a significant range of deviation on our measurements without accuracy between trials.

Normally, if we to do with more accuracy it should to have 3 measurements
Without any battery inside with power by ac
With battery inside but power by ac
With battery inside and power with this.

[Carrington]

Reducing the ground loop area, should reduce the noise induced in the.
I do not understand why they have not shielded it internally...
Why not you try to cover the wire of the probe with aluminum foil, seeking a Faraday cage.

[Flash2light]

filtering ripple as much as possible.
After this, the protection of every inductors farad cage.

The battery needs to pass the filter.

[Carrington]

https://www.eevblog.com/forum/testgear/review-of-owon-sds7102/msg248589/#msg248589

Tektronix TDS210 oscilloscope inside photos:





This finish is similar to that used in laptops. Conductive paint ready to spray... Where is it sold?
http://www.xsf168.com/en/About.asp
http://www.mgchemicals.com/products/protective-coatings/emi-rfi-shielding/super-shield-silver-copper-843/
http://uk.farnell.com/kontakt-chemie/emi-35-200ml/coating-conductive-emi-35-200ml/dp/2142398
http://es.farnell.com/electrolube/enscp400h/coating-nickel-can-400ml/dp/1675347?crosssellid=1675347&crosssell=true&in_merch=true&
http://www.caswellplating.com/copper-conductive-paint-4oz.html

...

By the way the TDS210 reaches up to 180 Wfmr/s.


http://www.chipdip.ru/en/video/id000276002/

[lemon]

Carrington, in my country we say "you get that you paid" (I don't know if there is meaning in english something.
The price of this oscilloscope when it was "young" was over 1500 euros.
But I agree totally with you, fine workmanship inside.

I think in past the TomC searched about this material like your links, I don't know if he found something, but the spray shield coating....yes they like me very well...

The ground noise is not legacy of Owon. Eight years old Tektronics you had more gnd noise that the initial SDS gnd noise. But I haven't any other experience with digital oscilloscopes only with analogues.

[TomC]

C23 has been removed.

Noise measured without the battery.

Battery measured noise is nearly the same.

If a test lead is straight. The noise increases. "The use of the battery 40mV" picture!


"if test lead move close to the psu or display. noise will increase."

Thanks, for the info and the test, that clears up the C23 mystery and shows the battery has some influence on the GND noise. I think I'm going to try some additional electrolytic capacitors to make up for the lack of a battery on my scope. I'll post the results if it makes a difference.

[TomC]

Reducing the ground loop area, should reduce the noise induced in the.
I do not understand why they have not shielded it internally...
Why not you try to cover the wire of the probe with aluminum foil, seeking a Faraday cage.

I've tried that, but didn't have that much of an effect, you have to ground the aluminum foil for it to make a little bit of a difference, and that's not that practical. The best way I've found to prevent the scope radiation from affecting the GND noise ( when the probe cable is close to the screen) is to loop the probe cable through a couple of large ferrites. One at each end of the cable.

[TomC]

Carrington, in my country we say "you get that you paid" (I don't know if there is meaning in english something.
The price of this oscilloscope when it was "young" was over 1500 euros.
But I agree totally with you, fine workmanship inside.

I think in past the TomC searched about this material like your links, I don't know if he found something, but the spray shield coating....yes they like me very well...

The ground noise is not legacy of Owon. Eight years old Tektronics you had more gnd noise that the initial SDS gnd noise. But I haven't any other experience with digital oscilloscopes only with analogues.

I sort of gave up on that approach because you also have to make sure the finish is grounded, otherwise the whole cabinet becomes an antenna. I addition, even if you get that right, you still have the radiation coming through the screen itself, which is the most powerful one. There is a transparent shielding material that can be used on the screen, but I wasn't able to find a source that sells it in small quantities at a reasonable price. For now the small ferrite that I put on the cable going to the TFT LED's reduces the radiation enough for the times I get the probe cable close to the screen.

[TomC]

Carrington, in my country we say "you get that you paid" (I don't know if there is meaning in english something.
The price of this oscilloscope when it was "young" was over 1500 euros.
But I agree totally with you, fine workmanship inside.

I think in past the TomC searched about this material like your links, I don't know if he found something, but the spray shield coating....yes they like me very well...

The ground noise is not legacy of Owon. Eight years old Tektronics you had more gnd noise that the initial SDS gnd noise. But I haven't any other experience with digital oscilloscopes only with analogues.

"You get what you pay for" is what they say over here, very similar!

[Carrington]

Well I have already purchased this: http://uk.farnell.com/kontakt-chemie/emi-35-200ml/coating-conductive-emi-35-200ml/dp/2142398
I will show the results, when I have everything ready,  I hope that Aidetek keep his word.


I could use an antistatic bag, only to test.
http://www.hollandshielding.com/226-Transparent_foil-en.htm
But the ferrite in the flat cable of the TFT eliminates much noise.

[TomC]

Well I have already purchased this: http://uk.farnell.com/kontakt-chemie/emi-35-200ml/coating-conductive-emi-35-200ml/dp/2142398
I will show the results, when I have everything ready,  I hope that Aidetek keep his word.


I could use an antistatic bag, only to test.
http://www.hollandshielding.com/226-Transparent_foil-en.htm
But the ferrite in the flat cable of the TFT eliminates much noise.

Carrington, the flat cable ferrite came with my scope, I don't know what the effect is if it's not there. The ferrite I was talking about is on the 2 wire cable from the adapter to the TFT backlight LED's. You can't see the ferrite itself on the photo because it's inside the blue shrink tubing.

[TomC]

Your mystery is like "Mitos of Ariadnes" (from Greek Mythology) same psu, identical adapter but the noise is differente, but remaining the answer of Flash2light what is marking of U2 in ver. 3.3. Probably, there is a difference there...

Well that's not too bad, I'll be more scared to look around for the answer if it resembled the story of Medusa, it wouldn't be cool turning to stone.

There are a couple of things I've been thinking about. I took a real good look at my new PSU board and discovered that one of the new decoupling capacitors is probably missing. There is no capacitor where C23 is supposed to be. C23 is supposed to be at the end of the adapter board connector. I see glue residue, as if the component was there but fell off during the soldering process. However, I don't think this would cause such a big difference in noise by itself.

Flash2light, can you tell me if this capacitor is present on your PSU board?

The other thing I've been thinking about is that I don't have the battery option. With a battery installed you have additional filtering for the 8.4V supply. The battery itself can act as a super capacitor. I don't know for sure if the results from dgmoore78@yahoo.com and Flash2light were obtained with the optional battery installed.

dgmoore78@yahoo.com and Flash2light, can you clarify this, and if possible, if your test was done with the battery installed, can you do the test again without the battery?

C23 has been removed.

Noise measured without the battery.

Battery measured noise is nearly the same.

If a test lead is straight. The noise increases. "The use of the battery 40mV" picture!


"if test lead move close to the psu or display. noise will increase."

Flash2light, when I first looked at your post I assumed that the photo was showing the noise with the scope powered by the grid and the battery removed. However, after looking at the photo closely it seems that the Power ON LED is off. That tells me that you were running the scope off the grid on battery power alone. Is that right?

So now I think that when you say: Noise measured without the battery. Battery measured noise is nearly the same.

It means that the 24mVpp noise photo on you previous post was taken with the scope powered by the grid and the battery removed, and that the noise is nearly the same if the scope is powered by the grid and the battery is installed. Did I get it right this time?

[Carrington]

Carrington, the flat cable ferrite came with my scope, I don't know what the effect is if it's not there. The ferrite I was talking about is on the 2 wire cable from the adapter to the TFT backlight LED's. You can't see the ferrite itself on the photo because it's inside the blue shrink tubing.

Mine does not have that ferrite. 

[TomC]

Carrington, the flat cable ferrite came with my scope, I don't know what the effect is if it's not there. The ferrite I was talking about is on the 2 wire cable from the adapter to the TFT backlight LED's. You can't see the ferrite itself on the photo because it's inside the blue shrink tubing.

Mine does not have that ferrite. 

Yeah, I suspected that because you have the version 3.0 adapter, I think the flat ferrite was installed by Owon when they released the version 3.2 adapter. Maybe you can contact Aidatek and see if you can get the ferrite along with your new PSU and Adapter boards. I've also seen some flat ferrites at Digi-key, I'm not sure if they have one the right size, but it wouldn't hurt to check. Good luck!

[lemon]

Oh, I left some hours the forum and you have writing a lot of... 

The C23 has been removed.
You can try to put one and see what happens, mine psu (mod) I have put a smd capacitor to this place.
TomC if you wanna to change some electrolytic capacitors look at my post that I had changed all the electrolytic caps and I had a good result to all spikes! (page 87, post 1302

We are to the right road...Carrington will try the EMI spray, TomC search for a transparent shielding material that can be used on the screen...fine!
TomC to mine if I put a small ferrite on the cable going to the TFT LED's there is no any reduces at the radiation, perhaps the various decoupling at the Led Drive Circuit works and ferrite can't to help any more.

"You get what you pay for" is what that I say...thanks TomC the forum isnt' technical support only but including and english teaching!

Carrington don't worry about flat ferrite and mine there isn't this flat ferrite inside. Probably they adding this ferrite from adapter ver. 3.2 and then.
Perhaps some member removed this ferrite to see if works or it is for decorating purpose!
 

[TomC]

TomC to mine if I put a small ferrite on the cable going to the TFT LED's there is no any reduces at the radiation, perhaps the various decoupling at the Led Drive Circuit works and ferrite can't to help any more.

That's probably what it is, the TFT backlight circuit is what's producing some of the noise radiating from the screen, the small ferrite filters some of that. But if you have already used bypass capacitors is like the ferrite on the PSU to adapter, it doesn't help very much once you have used bypass capacitors to filter much of the PSU noise.

I was thinking of using electrolytic capacitors to take the place of the battery, but from Flash2light post, if I read it correctly, the battery in or out doesn't make much of a difference. So that idea may not be so good after all.

Right now I'm starting to put the scope back together, since I had it open anyway I took some time to look around for any obvious blunders. I didn't find anything significant, just going to make sure that all the screws to the Z plate are tight and making good connection with the pads on the boards.

[Flash2light]

Your mystery is like "Mitos of Ariadnes" (from Greek Mythology) same psu, identical adapter but the noise is differente, but remaining the answer of Flash2light what is marking of U2 in ver. 3.3. Probably, there is a difference there...

Well that's not too bad, I'll be more scared to look around for the answer if it resembled the story of Medusa, it wouldn't be cool turning to stone.

There are a couple of things I've been thinking about. I took a real good look at my new PSU board and discovered that one of the new decoupling capacitors is probably missing. There is no capacitor where C23 is supposed to be. C23 is supposed to be at the end of the adapter board connector. I see glue residue, as if the component was there but fell off during the soldering process. However, I don't think this would cause such a big difference in noise by itself.

Flash2light, can you tell me if this capacitor is present on your PSU board?

The other thing I've been thinking about is that I don't have the battery option. With a battery installed you have additional filtering for the 8.4V supply. The battery itself can act as a super capacitor. I don't know for sure if the results from dgmoore78@yahoo.com and Flash2light were obtained with the optional battery installed.

dgmoore78@yahoo.com and Flash2light, can you clarify this, and if possible, if your test was done with the battery installed, can you do the test again without the battery?

C23 has been removed.

Noise measured without the battery.

Battery measured noise is nearly the same.

If a test lead is straight. The noise increases. "The use of the battery 40mV" picture!


"if test lead move close to the psu or display. noise will increase."

Flash2light, when I first looked at your post I assumed that the photo was showing the noise with the scope powered by the grid and the battery removed. However, after looking at the photo closely it seems that the Power ON LED is off. That tells me that you were running the scope off the grid on battery power alone. Is that right?

So now I think that when you say: Noise measured without the battery. Battery measured noise is nearly the same.

It means that the 24mVpp noise photo on you previous post was taken with the scope powered by the grid and the battery removed, and that the noise is nearly the same if the scope is powered by the grid and the battery is installed. Did I get it right this time?

-Powered by grid and battery not installed: noise about 30mvpp
-Powered by battery and grid not installed: noise about 30mvpp

But if the test lead is straight. noise increases more; battery use.

[TomC]

-Powered by grid and battery not installed: noise about 30mvpp
-Powered by battery and grid not installed: noise about 30mvpp

But if the test lead is straight. noise increases more; battery use.

Thanks for clarifying that.

[Flash2light]

This is ver 3.3 dc-dc board under side.

That's identical to mine (3.2), but yours had the smd capacitor under C34 installed at the factory.

Flash2light, can you read the markings on U2 on your board, on mine I see OBT 2?K CX10. The question mark is a character that I can't make out.

This is new photo lcd backlight dc-dc chip.

[TomC]

After putting the scope back together my ground noise results have improved. I don't have a definite explanation for this but I did a couple of things that may have had some influence.

1. I cleaned the flux residue from the PSU board with Radio Shack electronics cleaner. In general it wasn't too bad originally, but a couple of areas had a thick coating.

2. I cleaned the pads that contact the Z plane on both the PSU and the adapter board and made sure that the screws were tightly secured.

Before snapping the cabinet back together I tried connecting a 3300 microfarad electrolytic where the battery would be normally connected. It didn't make much of a difference on the GND noise.

When I connected the laptop to the scope to capture some waveform images, I noticed that the noise jumped about 10mVpp. In the past the noise was high enough that I didn't realize this had an effect. So I put a ferrite on the USB cable to help this. Still, the noise in the attachments is about 2mVpp higher than what I observed when there was no USB cable connected.

[TomC]

This is ver 3.3 dc-dc board under side.

That's identical to mine (3.2), but yours had the smd capacitor under C34 installed at the factory.

Flash2light, can you read the markings on U2 on your board, on mine I see OBT 2?K CX10. The question mark is a character that I can't make out.

This is new photo lcd backlight dc-dc chip.

That's a very nice and clear photograph, Thanks.