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Author Topic: REVIEW - Owon SDS7102 - A look at the SDS series from Owon  (Read 848297 times)

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Offline lemon

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1950 on: September 19, 2013, 04:18:11 AM »
Well done, TomC. I'll wait for your result.

I would like to test the scope without the Owon PSU, but I am thinking how manipulate the trigger output of the flat ribbon.
How is the right way to be done?
Sure, I need two independent voltages by -7.6V and 8.4V -  this is easy I have the appropriate psu - but the ac trigger output?

When dismantle (unfit) my scope to applying shielding, I found the time to take some photos to the others boards.

Here are with the full resolution, only an amount of compression for smaller files.
The photos are from the two buttons boards, the one is L schema of buttons (H1..H5 horizontal and F1..menu off vertical) the other is main menu buttons. Also there are photos from the mainboard, both of sides.
« Last Edit: September 19, 2013, 04:32:55 AM by lemon »
 
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Offline rf-loop

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1951 on: September 19, 2013, 05:15:36 AM »

I would like to test the scope without the Owon PSU, but I am thinking how manipulate the trigger output of the flat ribbon.
How is the right way to be done?
Sure, I need two independent voltages by -7.6V and 8.4V -  this is easy I have the appropriate psu - but the ac trigger output?


No need this trigger signal if you do not select trig source "AC". Afaik, this is only for this use.
(Note that it is also case if power come from battery. There need only Vbatt (~6V(min)  to ~8.?V (max8.4V))  and -7.6V)
(I have used it also with external +8V, -7.6V, +5.5V and +3.3V when I inspect TFT bus noise and front panel noise.. Also TFT backligt can drive with external Constant Current source (max/and normal 100% brightness around 180-200mA))
« Last Edit: September 19, 2013, 05:23:08 AM by rf-loop »
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
It is much easier to think an apple fall to the ground than to think that the earth and the apple will begin to move toward each other and collide.
 

Offline Carrington

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1952 on: September 19, 2013, 05:24:06 AM »
Hello everyone!

TomC:

When I get time I will read the article. Reflection and absorption, that's right, but who knows what's happening inside. We do not have the means to do a simulation, we only can make test. Woow...
Once shielded it only one thing is clear all the electrics fields are confined inside. Now, clearly absorbing materials type FFAM would help.
But I'm starting to wonder if it is worth spending more money on this thing.

Lemon:

Yes the shielding and z-plate have continuity but I need to check at which points. Will be later, I'm very busy but don't worry I will confirm you where it makes contact.

The oscilloscope does not need the ac trigger output to work, when running only with battery does not have it.
Your "motherboard" is very different to mine, and my ADC is from National.

AndrejaKo:

Woow, you removed the current sense resistor and noise bursts gone. LOL... Unbelievable.
Switching noise still remains.  :--



Is needed do more testing, but now I can't.
« Last Edit: September 19, 2013, 05:27:27 AM by Carrington »
My English can be pretty bad, so suggestions are welcome. ;)
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Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1953 on: September 19, 2013, 05:32:43 AM »
Well done, TomC. I'll wait for your result.

I would like to test the scope without the Owon PSU, but I am thinking how manipulate the trigger output of the flat ribbon.
How is the right way to be done?
Sure, I need two independent voltages by -7.6V and 8.4V -  this is easy I have the appropriate psu - but the ac trigger output?

When dismantle (unfit) my scope to applying shielding, I found the time to take some photos to the others boards.

Here are with the full resolution, only an amount of compression for smaller files.
The photos are from the two buttons boards, the one is L schema of buttons (H1..H5 horizontal and F1..menu off vertical) the other is main menu buttons. Also there are photos from the mainboard, both of sides.
I agree with rf-loop, there is no need to worry about this trigger, is only used when you select AC trigger as the source.
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1954 on: September 19, 2013, 05:42:57 AM »
After that, I removed the current sense resistor and those noise bursts I had after switching are now gone.  I'm thinking of putting a picofarad range capacitor in parallel with the resistor, since I'd like to have it there in case of overcurrent situation.

Interesting thing is that duty cycle remains erratic even with the current resistor removed. Switching noise still remains.
Andrejako,

I would try adding an electrolytic capacitor at or near the MC's VCC pin. Just in case the 8.4V don't have enough filtering at that point.
 

Offline lemon

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1955 on: September 19, 2013, 06:40:57 AM »
Thanks guys for the info.

@ Carrington = I''ll waiting for your feedback about continuity btw z-plate and shielding. It is important to me. Thanks a lot. As I saw you have an 8102, it is logical to have differently mainboard.
@ AndrejaKo = Nice observation but at the final all this psu is fully noising. At the end, I'll wait the TomC's work about this.
 

Offline AndrejaKo

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1956 on: September 19, 2013, 07:23:04 AM »
Andrejako,

I would try adding an electrolytic capacitor at or near the MC's VCC pin. Just in case the 8.4V don't have enough filtering at that point.

I added a 1 mF low ESR aluminium electrolytic capacitor directly to the hole where the current sense resistor connected to Vcc pin and the second lead to ground next to some exposed resistors. It made no improvement. 

@lemon
No, actually they changed their ADC vendor, if I remember correctly sometime in 2012. From serial number of your board, I see that it's the same batch as my old board. I remember that some time after that, they moved to National ADCs with secret part numbers. I think rf-loop wrote about that several months ago, but I can't find the post right now.
On the bright side, of all this PSU noise, at least I have an entertaining way of learning a bit more advanced electronics. My friends spend their time tuning their Yugos, while I spend my time tuning my scope :)
 

Offline rf-loop

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1957 on: September 19, 2013, 08:17:42 AM »
Your "motherboard" is very different to mine, and my ADC is from National.


Functionally exactly same. "RuiFeng" MXT2002  is functionally clone of ADC08D500.
There can use both. (but physically not directly pin-pin becouse "RuiFeng" add extra (n.c.) pins to every corner)
MXT2001 is 2x1GSa/s (SDS8102)  and MXT2002 is 2x500MSa/s (SDS7102).

Owon have used "RuiFeng" and other manufacturers ADC08D500 in SDS7102

Perhaps also some Rigol use "RuiFeng" ADC's.

Page from MXT "User manual"
and perhaps this picture is from MXT factory.
« Last Edit: September 19, 2013, 08:46:55 AM by rf-loop »
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
It is much easier to think an apple fall to the ground than to think that the earth and the apple will begin to move toward each other and collide.
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1958 on: September 19, 2013, 11:59:05 AM »
I added a 1 mF low ESR aluminium electrolytic capacitor directly to the hole where the current sense resistor connected to Vcc pin and the second lead to ground next to some exposed resistors. It made no improvement. 

AndrejaKo,

We are running out of options here. I was wondering, it seems that you have spares of most of the components for the -7.6V circuit, perhaps you could breadboard a clone of this circuit and see how it behaves. It's sort of a desperate measure, but you have tried just about everything else. It sort of comes down to something basically wrong with the design, or some influence on it by the PSU's circuit board environment.
 

Offline lemon

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1959 on: September 19, 2013, 03:44:49 PM »

...
@lemon
...
On the bright side, of all this PSU noise, at least I have an entertaining way of learning a bit more advanced electronics. My friends spend their time tuning their Yugos, while I spend my time tuning my scope :)

I agree totaly with you. We learn with it, it is like that we interesting to improve.  :-+

Your "motherboard" is very different to mine, and my ADC is from National.


Functionally exactly same. "RuiFeng" MXT2002  is functionally clone of ADC08D500.
There can use both. (but physically not directly pin-pin becouse "RuiFeng" add extra (n.c.) pins to every corner)
MXT2001 is 2x1GSa/s (SDS8102)  and MXT2002 is 2x500MSa/s (SDS7102).

Owon have used "RuiFeng" and other manufacturers ADC08D500 in SDS7102

Perhaps also some Rigol use "RuiFeng" ADC's.

Page from MXT "User manual"
and perhaps this picture is from MXT factory.

Many thanks for this info, rf-loop.
I have a query about this. If you see with attention the photo "Mainboard downside SDS_V3.3.jpg" that previous I have uploaded, there are some bridges to the left and up side of the Chrontel chip. Is that normal? Also, I must to examine the C146 at the left of this chip, in photo seems like to be damaged or to has a bad solder.
« Last Edit: September 19, 2013, 11:13:10 PM by lemon »
 

Offline rf-loop

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1960 on: September 19, 2013, 10:57:52 PM »
... there are some bridges to the left and up side of the Chrontel chip. Is that normal? Also, I must to examine the C146 at the left of this chip, in photo seems like to be damaged or to has a bad soldier.

There is Chrontel datalines D23,22,21; 15,14; (in picture looks like solder "bridge/GND")
Then you see data lines  D7,6,5  also connected to GND.

This Chontel chips is some amount complex. There is example 185 different modes (0-184). In many modes data lines have different use. (Table 7: Input data format)

Just example (not this case) mode 2. There is 3x8 bit data lines, but in this case Red use 5 bit, Green use 6 bit and Blue use 5 bit and other data lines 0. 

 My "quess" is that it just need these data lines only to GND? But I do not know what is selected mode exatly.


Chrontel 7026 SDTV/VGA Encoder



If you mean C164, it really looks very extremely bad in picture. Hand repaired(?) soldering with very poor skills? (also overall over the board solderings looks like there is some kind of problem in process?) Is it some kind of monday morning production?
« Last Edit: September 19, 2013, 11:31:37 PM by rf-loop »
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
It is much easier to think an apple fall to the ground than to think that the earth and the apple will begin to move toward each other and collide.
 

Offline Carrington

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1961 on: September 20, 2013, 12:43:35 AM »
Shielding+Zplane:
  Blue direct contact.
  Red, indirect contact. (Also through all gnd srews of Button_2F).
  Green, Contact, with back cover.

Screen+Zplane:
  Direct contact between the screen and the Zplane.

Zplane:
  New ferrites added.

Detail_1:
  Chrontel.

Detail_2:
  Broken Inductance (It came broken from the factory).
  This DC/DC converter power directly the whole DAC, analog and digital, any filter between.  :palm:

PSU_R:
  Red, avoiding gnd loops (I don't believe that their impact be noticed).

Main_R:
  National ADC (Lemon, my input stage is different from yours).
  U59 (7905) power the input stage  with -5V, directly connected to -7.6V PSU.



Lemon, could you try the shield case without the buttons board inside?
Thanks.
« Last Edit: September 20, 2013, 12:51:53 AM by Carrington »
My English can be pretty bad, so suggestions are welcome. ;)
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Offline Carrington

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1962 on: September 20, 2013, 12:54:43 AM »
Lemon this is the board to pull out of the case.
My English can be pretty bad, so suggestions are welcome. ;)
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Offline Carrington

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1963 on: September 20, 2013, 01:05:59 AM »
Different input stages.
« Last Edit: September 20, 2013, 01:09:13 AM by Carrington »
My English can be pretty bad, so suggestions are welcome. ;)
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Offline rf-loop

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1964 on: September 20, 2013, 02:20:15 AM »
This (lemon version) more low noise and higher BW (and less power consumpting)  front end (before ADC) have been also quite long time.

With this front end there have been ruifeng ADC and now also National. 

lemon board is, if I understand right, from 2011.

This lemon version  is developed from old "original" front end what was in production when this long original topic start by marmad.  This original "first generation" front end also mechanical construction was not good and it was also noisy. (it can see in old noise level tests (not related to this SMPS noise issue) (also there was big advantage in bandwidth/risetime)

After this lemon picture version there have been 1 major  change (analog front end designed nearly totally new - using now old and quite good two pathway principle (principle for two pathway front end originally designed by Tektronix)  and also some smaller changes. In this construction 7102 BW drop some amount but it is still very good for 100MHz scope but in other hand, there was quite big advantage in front end random noise level. 


I have made mistake when I have looked my stored pictures and thinking confusing amount of different versions.. and just accidentally think lemon version wrong.

« Last Edit: September 20, 2013, 04:36:59 AM by rf-loop »
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
It is much easier to think an apple fall to the ground than to think that the earth and the apple will begin to move toward each other and collide.
 

Offline Carrington

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1965 on: September 20, 2013, 02:36:45 AM »
This (lemon version) more low noise and higher BW (and less power consumpting)  front end (before ADC) have been also quite long time.
rf-loop then what are the main differences between the Lemon main board and mine?
Thanks.



Edit: Lemon, I just noticed that mine does not have that plastic (red), and therefore makes contact with the gnd of Button_2F board.
« Last Edit: September 20, 2013, 02:42:03 AM by Carrington »
My English can be pretty bad, so suggestions are welcome. ;)
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Offline Carrington

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1966 on: September 20, 2013, 03:44:09 AM »
Is this what I think? Power to digital and analog part separately, if so if we can add a low ohm FB.
My English can be pretty bad, so suggestions are welcome. ;)
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Offline rf-loop

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1967 on: September 20, 2013, 04:29:57 AM »
This (lemon version) more low noise and higher BW (and less power consumpting)  front end (before ADC) have been also quite long time.
rf-loop then what are the main differences between the Lemon main board and mine?
Thanks.


My apologies. I have downloaded many pictures collected from forum etc becouse it is more easy look when not need search forum long threads and not only this thread.
I have mixed now some pictures, perhaps becouse lemon and you have different shield box (without trimmers adjustment holes) over front end other side and then looked wrong BNC side picture (older version) and of course then think it have this older front end version)

In older version there was not these trimmers (resistor) but only capasitive adjustments  and these was also other side of PCB.

Now I look more carefully here directly in forum agen these pictures and also my own and collected pictures and now I'm even more confused with these many different versions but it was my mistake I think lemon version is more old than it is.
But in lemon version there is not these holes for adjust trimmer resistors or there is not at all these trimmers. 
I have seen these (R)trimmers only in Owon analog front end version what is made partially with separate discrete fet's. But now I'm not sure about anything... more and more confused with these many more or less different versions.

How many different versions they have? Who knows...
« Last Edit: September 20, 2013, 04:39:20 AM by rf-loop »
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
It is much easier to think an apple fall to the ground than to think that the earth and the apple will begin to move toward each other and collide.
 

Offline lemon

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1968 on: September 20, 2013, 05:46:40 AM »
Quote from: Carrington
Lemon, could you try the shield case without the buttons board inside?
Thanks.

I do it tomorrow.

I see that we have the same main button board version, some minor routing differences at the side with the bnc face of mainboard, I don't see any differences to trimmers there.
The main differences about our versions are to the other side with the most IC's, some different IC's companies, you have more trimmers but for my opinion is normal not because you haven't different version but because yours mainboard is for 8102 with 2GSa/s and mine if for 7102 with 1GSa/s.

Thanks rf-loop for the datasheet of Chrontel but I can't to find answer to my question there. I see the capture of Carrington that his Crontel has clear all the legs and I am thinking what is going to mine.
Is it different configuration that must joined some legs or it is bad production? I took one macro photo of this IC, see at attachment photos.
I am thinking to send them to Owon for their respond about this.
I am a little nervous about this, because at this area around there are two bad soldering components, the one is capacitor that we said (it isn't damaged, only very bad soldering) and the other resistor very closer to the IC.

If you see with more attention at the macro capture photos, the joined legs have the same "ground planes" under. If there are common paths, why they applied extra joined with soldering? Weren't enough the common paths?

Of course from datasheet the main purpose of this IC is to encoder the signal to vga output. I don't see any problem with the external TFT monitor.
« Last Edit: September 20, 2013, 05:53:47 AM by lemon »
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1969 on: September 20, 2013, 01:58:52 PM »
Very sloppy soldering! :--

I think rf-loop is right, some kind of production problem and they were trying to salvage some (or all) of it with hand repairs. :palm:

They may have had some of the bridged pins come loose in some boards during that production run, and decided to solder them by hand on all the boards just in case. ::)

The sloppy soldering and the decision to ship subpar boards is a blackeye for Owon in my opinion! :--

I wouldn't blame you if you take them to task over this, and at least let them know that this behavior has not gone unnoticed! >:(
 

Offline TomC

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1970 on: September 20, 2013, 02:04:08 PM »
Detail_2:
  Broken Inductance (It came broken from the factory).
  This DC/DC converter power directly the whole DAC, analog and digital, any filter between.  :palm:

In my opinion, to ship something with broken components is not cool either! :--
 

Offline rf-loop

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1971 on: September 20, 2013, 03:00:24 PM »
There some versions
old front end amplifier and then more new with discrete FET's
Between these there is also other version still with IC front end amplifier.
And between these versions, I suspect is lemon version? Perhaps still
this IC amplifier  but physically different topology (when they change circuits to other side of PCB)
(here is not this one middle version picture)
Major change was change from IC amp to discrete FET amp.
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
It is much easier to think an apple fall to the ground than to think that the earth and the apple will begin to move toward each other and collide.
 

Offline AndrejaKo

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1972 on: September 20, 2013, 08:45:47 PM »
Looks like I have one more problem to add to my list of troubles with this scope:
After being turned off for a while, trace appears in random location.  It does self-calibrate fine and after self-calibration it works fine, unless it's been powered off for a while. I took apart the whole scope and inspected everything in great detail. There were a few minor issues. One of the not so minor were horrible joints of CX1 capacitor on the input filter. They were so bad, I could move it by hand and there was even a bit of lifted trace there. I'm a bit embarrassed I did not notice this before.

Anyway, on the main board, there's a rechargeable lithium battery marked MS621FE whose voltage is 2.749 V. I'd expect it to be a bit higher, since the scope was running for quite a while before being turned off last time, but the value is within the datasheet limits, so I guess it's fine. Also the scope kept the date and time, so it looks like the auto-calibration data isn't lost.

With this main board, I did have some drifting with temperature on channel two, but it was a few millivolts. This seems like a systematic problem and running the scope for some time doesn't change the difference, except for the small amount of drift that was there before.

I'm really starting to thing that this scope is a bit cursed. :)
 

Offline lemon

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1973 on: September 20, 2013, 10:23:10 PM »
2.75V is mine battery, too.

What to say....all of these are problems of production line. Chinese people learns easy but no with our moneys!
Before one month I bought a new Rigol DP832 psu and there was a production critical fault to one board, but Rigol quickly corrects (twice) this fault and continues to coverage the customers.
Nobody is perfect but the aftersales services is important to customers.

...
Edit: Lemon, I just noticed that mine does not have that plastic (red), and therefore makes contact with the gnd of Button_2F board.

Done and this test without any significant result, same noise (see at the attachment file).
Have in mind that with this test, dosen't work the Ch1, only Ch2.

By the way, there is a possibility the fault to be from the non continuity of shielding between the two cases? I can't to explain better (see the arrows at the capture)
« Last Edit: September 20, 2013, 11:00:44 PM by lemon »
 

Offline Carrington

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Re: REVIEW - Owon SDS7102 - A look at the SDS series from Owon
« Reply #1974 on: September 20, 2013, 11:50:28 PM »
If it could be, because then is not properly a Faraday cage. I'm thinking that the Zplane can be like an antenna deflector, and therefore the shielding makes it worse, and would be necessary, to isolate the different zones inside, and this is very difficult.

However I've tried to isolate the area (with the plastic) and the noise increases by about 10mV. Also, if not screwing all the screws that attach the Zplane with the shielding the noise increases other 10mV.

I've also tested with the board Button_2F outside and again the noise increases.

The DC/DC converter that you can see on image Detail_2 generates a lot noise. Rf-loop says that it does not affect but sorry, I do not agree.

The next test will be with the whole scope and probe inside a Faraday cage, because I can not get off of that tone on 106.5MHz, I think that comes from outside.

Note: Yes, the BNCs make contact whit the area marked in yellow.
« Last Edit: September 20, 2013, 11:51:59 PM by Carrington »
My English can be pretty bad, so suggestions are welcome. ;)
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