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

[akis]

Thanks, I have now ordered one of these scopes and hopefully it will arrive soon.

[king2]

Hi!

I have SDS8202 scope and battery option for it, to measure signals in devices directly connected to AC power.
And when I have bought battery, I carefully read manual, and found that:
 - "do not connect ground socket of probe to anything except GND AC terminal, or you will get big-bada-bum"
 - "when workinh on battery power, always connect GND terminal on back of scope to real ground"
 - BNC ground and ground terminal at back of scope connected together

So, is I want to see what happening after line filter and diode brigde, I cannot, even with battery. I should or leave scope ungrounded, or it can be broken, due to voltage difference between null wire in AC wall socket and ground after line filter and diode bridge (I just will connect it directly via probe GND -> scope GND -> GND wire of wall socket -> null wire of wall socket).

So, what should I do do correctly measure such signals with Owon SDS?
Leave GND unconnected?

Thanks for answer!

[king2]

I have only one idea:
  1. Connect rear connector to ground
  2. Do not connect probe grounds to anywhere
  3. Connect probe signals to both points
  4. Turn on Math -> Subtraction

But what I will get - I do not know, especially about noise.

I have tried some schematic (very simple): AC source -> diode brigde -> two lamps connected via multimeter in current meter mode (so multimeter worked as current shunt). I connected scope (without grounding and on battery power) to both terminals of multimeter and expected to look at current waveform, may be slightly pulsating.

But I was very frustrated - I got very noisy signal, that was distributed above (this was expected) and BELOW zero level.
So, I got almost simmertical AC current after diode brigde (but if I measure voltage with scope after bridge I see traditional picture of rectified AC).

WTF?
How theese two lamps can cosume negative current through diode bridge???
May be I have connected something wrong?

[digsys]

What you see is correct. You can not just connect the 2 tips of each channel and expect a +- sum
The GND of the tip MUST be connected and it is always the GND of the P/Supply or Mains.
You have 2 choices, an isolation transformer EITHER on the Signal, safest, or on the DSO mains supply.
In the 2nd case, the GND of the DSO lead is still at mains, so you have to be VERY careful not to touch it,
unless you ALSO provide an Isolation transformer to the DUT. Then you can only touch ONE part at a time.
Isolated CRO leads are rare and expensive !!

[king2]

No, I have tried to connect ground and tip of one probe, on one channel, without Math.

My scope works on battery, so it does not need mains to work.

When I have tried to connect it without groundinghs, I got strange signal.
When I tried to connect rear ground connector to ground via resistor (for safety at start), power source was immediately turned off (protection).

So, for now I have no way to measure current (and get right results ) in circuits, connected to mains supply?
This is sad.

[digsys]

No, I have tried to connect ground and tip of one probe, on one channel, without Math

That's the only way it will work, unless you buy a special isolated probe or an isolated current probe.
ALL oscilloscopes have that issue - ie You HAVE to connect the GND wire of the probe, which then puts
the WHOLE oscilloscope at that potential. As I said, I OFTEN measure mains, Live side, BUT you need to
take precautions !!!! We use an ISOLATION transformer on the DEVICE under test. That gives us a
LOT of safety, as long as you only touch ONE connection at a time.

My scope works on battery, so it does not need mains to work.

Doesn't matter. The Probe GND is still Referenced (connected) to the oscilloscope GND / Frame etc

When I have tried to connect it without groundinghs, I got strange signal.

YES. The signal HAS to be across the probe tip and GND wire (which should be as short as possible).

When I tried to connect rear ground connector to ground via resistor (for safety at start),
power source was immediately turned off (protection).

Now you're experimenting in dangerous territory !! Don't do that.

So, for now I have no way to measure current (and get right results ) in circuits, connected to mains supply?
This is sad.

See above. All in the same boat, all have the same options

[king2]

Sad, but I cannot use isolation transformer, because load can eat up to 300v/2kWt.
I know that electricity can move me under ground level , that's bacause I used resistor and measured voltage on it, before any dangerous connections. But this is not main question.

Strange signal, below and above zero line was while scope was connected to signal source via probe tip and probe GND and nothing else. Scope was ungrounded, so rear terminal was left unconnected. Scope worked on battery. In fact, scope was connected only to signal source. No mains power, no grounding of scope itself.

I do not understand, why I got very strange AC waveform, containing negative levels - while measuring voltage on shunt in DC power without any inductive load (only two lamps).

[alm]

My scope works on battery, so it does not need mains to work.

But it does need ground to be safe. From the (Engrish) manual:

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

I do not understand, why I got very strange AC waveform, containing negative levels - while measuring voltage on shunt in DC power without any inductive load (only two lamps).

Capacitive coupling between scope ground and other circuits? Since a scope is designed to work with a low impedance to ground, parasitic capacitance between ground and other circuits is not usually an issue.

So, for now I have no way to measure current (and get right results ) in circuits, connected to mains supply?
This is sad.

Try using a current probe.

[digsys]

Question first> is this the place here to ask questions or make user comments and that type of stuff? or is there another place

Welcome to the forum. You would always start a new question in a new thread. You can simply create one in an appropriate section eg Beginners.
Adding to someone elses thread is called "hijacking", and in some forums, ppl can get real bitchy. Newbies are safe here though :-)

SDS7102V ...  battery in and charged (green light) then turn the scope on and i have noticed when one uses the scope and then
 turns it off the battery charge light is back on (yellowy red) ...

This is quite normal. Whenever a system starts up from cold and has a battery installed, it will always check the state of the battery !!
It often need to do that by trickle charging it for a short while until it figures out if it is charged or not. After all, with the CPU off, it can't tell what
you may have done to it. Generally, the battery is NOT in use while mains power is connected. Prolongs the battery life.

[digsys]

EEEP!! Pic2 doesn't look right, but I don't have that scope, so I have no clue at this point.
Luckily there are MANY users here that do, and they can definitely help more. There's a seller here, aghp,
hopefully he can help, or START a new thread with the question.

[saturation]

Now this doesn't sound good at all.  Photos would help.  On your original problem if you short the probes it will form an antenna and pick up a lot of noise; if you FFT it you may be able to identify the key sources, like radio stations.  For checking the DSO inherent noise, you should short the input with a 50 ohm terminator.

http://www.tmworld.com/article/321927-Quantify_noise_with_a_DSO.php

No it does not look right aye , i also left out some bits as i still feel like thread stealing now that i know i'm in the wrong spot so i'll keep it short or not at all from now on , but more the bits are> i can see that noise in all signals displayed even in the 2 to 4v @20mhz range , it's superimposed on it , also the scope keeps seizing up and needs rebooting , and now as this is my first digital scope i seem to think that it is very slow sometimes and plays catchup on even basic signals , and there is nearly always a ringing in the center of the screen on a signal , anyway i have emailed OWON service and the ebay seller to see who wants to take up the issue and hopefully it'll be sorted out , and not solely from the money spent aspect , from the "i like the scope" aspect (if it was working correctly that is ).

cheers , and thanks for the input.

[aghp]

Here you may find some tests about Owon noise.
https://www.eevblog.com/forum/product-reviews-photos-and-discussion/improvements-in-owon-sds7102-hw/



also here
http://owon.freeforums.org/      (it do not show images and links to Guests)
      http://owon.freeforums.org/   (here are some copy becouse this show also links and images to guests)

As others have tell, probe is good antenna. It is just HF antenna after you connect GND wire to center tip.

There may be lot of RF noise in your environment.

What is your oscilloscope version?

Do you have 50ohm BNC terminator available? (for some tests)

[digsys]

Guess you might as well face it ... you did get a lemon, sure sux. Hopefully the seller / manufacturer will do the right thing ASAP.
Good luck

[aghp]

Becouse I do not know who is your seller and I do not know if they are professionals or just selling "nice boxes" I will try help littlebit..

First it need solve if there is problem in oscilloscope. This can do if do right things seriously.
)from Owon you can not now get any answer. (In China is now Dragon festival time and nearly all is closed)

But first. If you show some picture from test, please pick up image from scope screen using USB stick or using PC software.
Do not show these kind of PC software pictures what you show before. I want see authentick images from oscilloscope itself (scope TFT screen copy).

All next instructions do with oscilloscope continuously connected to powerline and battery fully charged or oscilloscope without battery module.

1. set scope to factory "default".
2. Keep oscilloscope powered on continuously 30-60min.
3. Disconnect all probes, wires etc so that all terminals are empty, even LAN cable and USB cable. Just scope alone without touching anything. Only wire connected to whole oscilloscope is powerline. Oscilloscope inputs need be just without anything connected.
4.  Start selfcal and wait it is finished. Do not touch oscilloscope when it is running selfcal. Do not even keep your hand near input connectors.
5.  Shut scope off and immediately on.
6.  For sure all is defaulted do it now agen (so I can relly be sure it is default.)

Do not change anything after full factory default but just next .
Do not connect anything to inputs. (exept: IF you know what is 50 ohm terminator and you have these then connect these to CH1 and CH2 inputs and later tell if you have used these or just open inputs)

Connect usb to PC and look you can pick up screen image. (select "Image" in PC oscilloscope software ports setting)
And make settings where you want it save images.

7. Turn both channels Volt/div so that they both show 200mV (becouse they have 10x it is actually 20mV/div in scope BNC)
8. Change acquire lenght to 1M and acquire normal.
9. Change Horizontal speed to 100us/div
10. Change dipslay persistence to 2s
11. Let it run some seconds without touching oscilloscope and hand more than 50cm away from inputs.
12. With PC,  pick up image then wait 5 seconds and pick up next image with same settings)
13. Turn both channels to 2V
14. Let it run some seconds without touching oscilloscope and hand more than 50cm away from inputs.
15. With PC,  pick up  image then wait 5 seconds and pick up next image with same settings)

16. Then take 50 ohm terminators out if you have used these.
Connect Owon probes to CH1 and CH2. Set probes to 10x.

17. set oscilloscope to factory default.
18. Connect BOTH probes together to 1kHz probe comp output. (in this time do not connect probe GND wires - both separately just floating.
19. Set Horizontal to 500us/div
20. Let it run some seconds without touching oscilloscope and hands more than 50cm away from probes or scope.
With PC,  pick up  image or two

Now you have 5 - 6  images.
Convert these .BMP to ecample .PNG  using some software, example Irfan or what ever what can do it. (becouse .BMP files are 1.4M and PNG is maybe 20k.

Show here these images. I will look these and if there can see some problem I will tell it, if there can not see problem then we do more tests. But I can try help you only if you can follow exactly "instructions".

If there is something you do not understand please ask example using PM

[qww830]

I repairing an SDS7102 which had been broken when high voltage was applied to inputs.
Few components on channel 1 and external trigger inputs were replaced and now device works good, but I've found one issue with external synchronization input:
I connect probes to channel 2 input and synchronization input and apply a composite video signal from my camera to both probes simultaneously.
Then I select a synchronization on video signal and an "EXT" source in the trigger menu.
In this mode trigger works fine, I can check this by disconnecting external trigger input to ensure that the oscilloscope is synchronized from external trigger.

Then I switch a synchronization source to "EXT/5" and see that synchronization does not work.
After some tests I've found that in video trigger mode the oscilloscope triggers on channel 1 input when "EXT/5" is selected in the trigger menu.

This is definitely a problem, but I don't know is the root cause hardware or software.
Thus guys, could you please check this on your devices - just apply video signal to channel 2 and ext trigger inputs and try to synchronize with "EXT/5" trigger source.

Device S/N is 71021209XXX with 2.5.1 FW.

Thanks in advance.

[tinhead]

Here you may find some tests about Owon noise.
https://www.eevblog.com/forum/product-reviews-photos-and-discussion/improvements-in-owon-sds7102-hw/


As others have tell, probe is good antenna. It is just HF antenna after you connect GND wire to center tip.

There may be lot of RF noise in your environment.

Do you have 50ohm BNC terminator available? (for some tests)

right, in my environment a cheapo 50ohm terminator is picking up a lot of RF noise,
even a good one is still picking some crap up (no matter if BNC or SMA terminated).

I got the best results with piece of copper foil (alu is fine to) closing/shilding the BNC - but not shorting channel input to GND.

[EU1]

Then I switch a synchronization source to "EXT/5" and see that synchronization does not work.
After some tests I've found that in video trigger mode the oscilloscope triggers on channel 1 input when "EXT/5" is selected in the trigger menu.

I've reproduced this on my unit. Thus it is a common issue.

[Dread]

Hi Folks

I am new here but have been reading many post and watching daves videos for months.  I figure I am now fully qualified to fix any broken Breast pump that may come my way! If not; depending on the owner I will do it the old fashion way 

Anyway I wanted to post and let you guys know I just pulled the trigger on a AKTAKOM ADS-2221MV with battery which is the same as an OWON 8202MV just a different sticker on the front which saves a lot of $$ and gives me a 3 year warranty that is covered by Aktakom in the USA so I don't have to ship it back to China if I have a problem.

I also purchased a AKTAKOM AWG-4110 function generator on a whim, I have no idea what re-branded generator this is so if anybody knows please let me know.

Let me say it's very nice to be on this Forum, you guys are very civil as compared to many forums I have been on.  I am also a Ham Operator and have been an EE for about 25 years and a programmer for 10 years.   I bought the OWON because my TEK 2430A finally died and to repair it I need another scope but unfortunately nobody I know has a scope or they have a  rubbish 10 MHz model from 1960.  So I decided after reading this thread to get the OWON and roll the dice.

I will post back in a few weeks when I have received it and done some tests using my Ham gear for analysis and see how she works out.

All the best guys and thanks for so much useful info.

BTW I really wish Dave would do an OWON review, it looks like you just won't dabble in low end DSO's market again and that’s sad because it just leaves Rigol as the only torn down reviewed scope.   I respect Dave but come on you have 3 or 4 video's on Rigol why not give OWON a go and let’s see how she stacks up.

[T4P]

Siglent SDG1010

[Dread]

Siglent SDG1010

Thank you. I see it is also see the LeCroy Wavestation.  Wow what a price difference between the Siglent and LeCroy, I wonder if they are exactly the same internaly?

[T4P]

Same. Entirely same

[Dread]

Received my  OWON 8202V (AKA Akatkom 2221mv) and I must say I am very happy with it.
They seemed to have fixed many of the problems that were pointed out about the 7102.

1) The Buttons and knopbs all feel very solid the buttons to the side of the TFT have no play or wiggle in them as the whole button assembly seems to be mounted differently.

2) No noise in Channel one or any of the channels.

3) The fold out legs seem to be different because I don't have any problem with the unit sliding back when the upper buttons are pressed.

I ran her up to 150 MHZ with no problems, I will also did some extensive tests on accuracy up to 10MHZ and that seemed very good.  I did find a slight Vpp difference but that might be cable loss so I will have to do a lot more testing to find out.
I will also be testing glitch capture and the Waveforms/S stuff.  I can say that so far it has been very impressive, I will keep you guys informed or make a new thread. I have only had it for 14 hours so I got a lot to check before making a detailed post.

[Dread]

An update on Item one of the 8202V.  The right side function buttons do have a slight wiggle, I had to look at it under a bright light and noticed it.

Exporting a waveform is very nice feature, I like being able to open it up on Excel and graph it out.  The 10M depth really generates a lot of data points so its not practical to export the whole buffer but it's great for exporting out a glitch or some event.

The Fan is whisper quite when the scope is in the normal bench position but it does make a whir sound if I lift up the scope while its on and the sound stays there for a 20-30 seconds after I put it back on the bench, almost like the spindle has to reseat itself.

Measuring voltages is kind of odd in that the 5V test signal registers as 5.040V to 5.120V.  Not sure whats going on but I need a second scope to confirm the readings.

[tlu]

Hi Tinhead,

Seeing how you are the foremost resident hacker of the Hantek dso5062b on this forum, I was wondering if the owon sds7102 can be hacked as well. Mostly, I see the firmware is the only major issue besides the low waveform refresh rate which I really care less about since I'm not using it to find glitches or rump pulses. Do you know what OS the sds7102 is running or if it is even possible to hack to get better UI? I'm deciding on the sds7102 and Hantek dso5062b. Great work on the Hantek dso5062b by the way.

Thanks,
Tim

[remy_m]

Measuring voltages is kind of odd in that the 5V test signal registers as 5.040V to 5.120V.  Not sure whats going on but I need a second scope to confirm the readings.

It happened the same on my SDS7102. If u move the  wave down and decrease the V/div so the wave is 'bigger' gives more accurate reading ( I guess it has to do with the fact that it has a 8 bit ADC).

Cheers!