Author Topic: Project Yaigol: Fixing Rigol scope design problems.  (Read 79363 times)

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Offline Bud

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #125 on: March 17, 2016, 03:47:31 am »
Good discussion folks, all opinions are welcome. My motivation was to make circuits work as they should, that is all. But having observed what i observed my equipment shopping list will not have  Yaigol again. Life is too short to have too many unknowns.
 

Offline wraper

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #126 on: March 17, 2016, 03:47:58 am »
... And there isn't any LDO oscillation in my scope.

Interesting. Any chance you have an SA and can check the PLL on your non-A DS2000?
No, I don't have a SA, only a desire to have it  :-DD.
 

Offline AndyC_772

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #127 on: March 17, 2016, 03:57:25 am »
Good discussion folks, all opinions are welcome. My motivation was to make circuits work as they should, that is all. But having observed what i observed my equipment shopping list will not have  Yaigol again. Life is too short to have too many unknowns.

You've done a nice job of design verification; something which I'm sure we'd all hope and expect the original designer would have done.

Now that you've implemented the fixes, are you able to show any before/after screen captures from the scope itself which show the benefit of these changes?
 

Online tggzzz

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #128 on: March 17, 2016, 04:09:31 am »
I don't actually care about the specifics of how your legal system works.
In that case why did you make any comments about it in the first place?!
It is also worth avoiding making incorrect comments on subjects you don't know anything about.

I made a comment about getting the system involved at all, which has nothing to do with the mechanics about it. The comment about them not needing to make them profit was tongue in cheek anyway, I don't see why it needs to be held to the same standard as if I seriously claimed they would. None of this invalidates my suggestion that we not get them involved at all.

Not making incorrect comments on subjects I don't know anything about is why I didn't explicitly claim they make money on this.

Pays to read completely.

I did read your post completely; it was very short and contained neither those points nor caveats.

Anyway, at this point it has become extremely boring.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Online tggzzz

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #129 on: March 17, 2016, 04:12:30 am »
Good discussion folks, all opinions are welcome. My motivation was to make circuits work as they should, that is all. But having observed what i observed my equipment shopping list will not have  Yaigol again. Life is too short to have too many unknowns.

That is a sane conclusion with which I thoroughly agree.

Thank you for your illuminating efforts.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
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Online IanJ

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #130 on: March 17, 2016, 04:43:15 am »
Three, if you could perform tests that demonstrated performance improvement using more common tools (DMM, another scope, signal reference), that would allow more of us following along at home to verify our results.

Well, it would have to be........I err, umm, don't own a Spectrum Analyzer (real)......but yes, I was thinking about a video. I have a DS2072 (that thinks it's a DS2202).

Ian.
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Offline marmad

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #131 on: March 17, 2016, 04:46:35 am »
But having observed what i observed my equipment shopping list will not have  Yaigol again. Life is too short to have too many unknowns.

I can completely understand your feeling, Bud - I've experienced the same sensation myself. But I'm curious if this is the first piece of Chinese test equipment you've purchased?

Having owned briefly / tried extensively an Owon, Hantek, and Siglent beforehand, the Rigol DS2000 was the first cheap Chinese DSO that I could even stand to use (at least in 2012) - and I'd just point out that the PLL/LDO problems you've discovered are in the same league as a plethora of other insane hardware/firmware gaffs I've experienced/seen in a wide range of Chinese brands and Chinese equipment.

As much as many of us (including me) complain about mistakes in Chinese T&ME, in essence, that's what we're paying (or literally, not paying) for: electronic design mistakes, spotty manufacturing, and incomplete and buggy firmware.
 

Offline bitseeker

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #132 on: March 17, 2016, 08:38:41 am »
Well, it would have to be........I err, umm, don't own a Spectrum Analyzer (real)......but yes, I was thinking about a video. I have a DS2072 (that thinks it's a DS2202).

+1 on the video, Ian. Although the FFT in the scope isn't a (real) SA, might it be good enough? The original noise spectrum and the final clean peak are quite apparent.
I TEA.
 

Offline Bud

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #133 on: March 17, 2016, 06:10:22 pm »
The internal scope FFT is poor in the first place, I think I did not notice any improvement, its noise is dominated by the 8-bit ADC limits. What should certainly improve is the external FFT for which you capture a long waveform file and load into external software capable of processing the waveform format.
 

Offline Bud

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #134 on: March 17, 2016, 06:13:46 pm »
Part 7 is now posted, and thermal radiometric files supplied in Part 8.

I am going to take a break as I need to work on other things and writing this article has stolen enough of my sleep time. I may return to Part 5 and 6 later.
« Last Edit: March 17, 2016, 06:16:20 pm by Bud »
 

Online tautech

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #135 on: March 17, 2016, 06:48:34 pm »
Oh men, too much work attaching pictures...
Nice job on the Pt. 7 post, see you can do it.  :-+
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Offline Emi

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #136 on: March 17, 2016, 06:56:07 pm »
ah ah bud...this time i discovered this tweak just before you  ;)     the first mod i've done is a little heatsink on the adc... damn hot ! i could'nt put my finger on without burning first!  :'(
now its warm yes , but will not hurt anymore....
Next step, a silent fan !
« Last Edit: March 17, 2016, 07:47:14 pm by Emi »
 

Offline Dave Atom

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #137 on: March 17, 2016, 07:00:41 pm »
Good discussion folks, all opinions are welcome. My motivation was to make circuits work as they should, that is all. But having observed what i observed my equipment shopping list will not have  Yaigol again. Life is too short to have too many unknowns.

Sorry for what may be a silly question, but I think either I am reading things wrong, or I am just suffering from information overload :

Should I, or should I not, invest in a DS1054Z as my first digital scope ?

I appreciate there are issues, with everything from design, build, hardware, & software, but are they game changers in so much that as a complete novice with little hope (currently) of modifying the scope, should I steer clear of the device ?

(I have noticed the mains lead hasn't been flagged as faulty :] )
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Online tggzzz

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #138 on: March 17, 2016, 07:15:34 pm »
Should I, or should I not, invest in a DS1054Z as my first digital scope ?

Yes, repeat no. It is the best device (given some purposes/constraints), repeat there are much more appropriate devices (given other purposes/constraints). You'll never notice the failures, repeat the failures make it useless.

All those statements are correct. Beware those whose statements fall into either camp; you will find both types here.

And I hope you can guess the next thing you should do if you want more specific advice. But please don't do it in this thread - start a new thread!
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline nidlaX

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #139 on: March 17, 2016, 08:05:57 pm »
Very interesting! Another thank you to Bud for conducting this thorough investigation and providing such detailed documentation and instructions. I cannot help but think how much this information would be worth from a product development standpoint (clearly too much for Yaigol to invest in?). I don't own a DS2000 series scope, but I think the information still benefits me as a DS1054z owner (not to mention the entertainment value! :-DD).

Based on the followups from other owners, it seems like part of the issue is yet again attributable to poor quality control? Willy-nilly use of "equivalent" components without checking design compatibility...  :palm: Looks like someone is staking out the Shenzhen market for daily specials again.
 

Offline SaabFAN

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #140 on: March 18, 2016, 05:12:56 am »
@Dave Atom:
I wouldn't say that the DS1054Z is a bad scope. It just has its flaws that are expected from a company that had to cut corners on everything to get the price down to have even the slightest chance of getting into the market.
So far I haven't run into any serious issues with my scope and really like the 24MegPoint memory, which seems to be one of the things the Rigols really shine at: Every Rigol-Scope comes with tons of memory compared to other brands - even Tektronix and Keysight don't offer that amount of memory in their devices.

What I absolutely don't like is the fact that the Firmware behaves inconsistently. Sometimes I get immediate responses when turning the offset-knob, at other times (same settings btw.) the scope seems to be bogged down by some random stuff and it takes a while for the changes to appear on screen. Also the FFT, as seen in a video by Dave, is horrible.

But it bugs me that I have a potentially horrible looking ADC-Clock in my scope, as well as what appear to be Schroedingers LDO (It could be oscillating, or not... I have to look at it to know)^^
So my Advice: If you can live with the quirks of the Rigols, get one. If not, get an equally expensive Tektronix TDS-Scope on ebay and a healthy supply of electrolytic capacitors :)

Btw. I suspect Siglent, Owon and the other chinese brands to have similar problems. Can somebody check their devices?^^

Has anyone checked the DSA815 for any problems similar to the Rigol-Scopes?
« Last Edit: March 18, 2016, 05:16:03 am by SaabFAN »
 

Offline Bud

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #141 on: March 18, 2016, 05:31:46 am »
Oh men, too much work attaching pictures...
Nice job on the Pt. 7 post, see you can do it.  :-+

Thanks for the tip, tautech, it was a bit messy at first but worked in the end.  :-+
 

Offline nctnico

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #142 on: March 18, 2016, 06:45:05 am »
Oh men, too much work attaching pictures...
Nice job on the Pt. 7 post, see you can do it.  :-+
Thanks for the tip, tautech, it was a bit messy at first but worked in the end.  :-+
Regarding the temperature: It is better to measure using sensors with the case closed so every device has it's 'designed' airflow. Even a little bit of airflow makes a huge difference so it is hard to compare measurements with an open case versus a closed case + airflow.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Howardlong

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #143 on: March 18, 2016, 06:49:10 am »

Sorry for what may be a silly question, but I think either I am reading things wrong, or I am just suffering from information overload :

Should I, or should I not, invest in a DS1054Z as my first digital scope ?


This thread probably is not the best one for a prospective $400 scope purchaser to read. While it's not without its features, it took quite some time for the infamous jitter bug to become the stuff of folklore despite many thousands of users.

There is still no other scope out there at this price point with the same specs or real practical use. If $400 is your price point, it's end of story.

 

Offline wraper

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #144 on: March 18, 2016, 06:57:46 am »
There is still no other scope out there at this price point with the same specs or real practical use. If $400 is your price point, it's end of story.
There are and with better specs, GDS-1000B series GWinstek. The only advantage of 1000Z is ability to unlock.
 

Offline Howardlong

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #145 on: March 18, 2016, 07:04:08 am »
There is still no other scope out there at this price point with the same specs or real practical use. If $400 is your price point, it's end of story.
There are and with better specs, GDS-1000B series GWinstek. The only advantage of 1000Z is ability to unlock.

I'd like to see a 1:1 to back that up in terms of specs and practical use.
 

Online Alex Eisenhut

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #146 on: March 18, 2016, 11:33:40 am »
Super awesome. Is it worth it to create a Digikey BOM or outright sell a kit with all parts required for a fix?
 

Offline Bud

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #147 on: March 18, 2016, 01:31:19 pm »
Hi..
Bud says  lt1038  is a fixed reg ...
but from ds i assume it's adjustable!
how can he change it on the fly ?
i dont understand this step :-//

Sorry my bad, this is what happens when you write in the middle of the night and after 9 months...

I replaced with LT3080, an adjustable regulator with only one set resistor. So I removed one resistor and replaced the other - see the datasheet for the set resistor formula.
http://cds.linear.com/docs/en/datasheet/3080fc.pdf
 

Offline Bud

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #148 on: March 18, 2016, 02:34:36 pm »
Some additional supporting artefacts for the project articles:

Just for fun I attached demodulated audio for the DS2072A PLL before and after the fix. The bad PLL had FM modulation that could be demodulated into audible range. I did it with my HP 8594E spectrum analyzer that had that capability. In the Before mp3 file nasty modulation is present, this is how your unfixed PLL would sound if you tune to it at 1GHz with a FM receiver. In the After mp3 file there is no modulation, only background noise which I artificially made louder because the audio was too quiet.

A zip archive with a video of the 6.3V shared power supply rail oscillating. Had to zip it because could not attach a video file.

A high res (well sort of) version of the landscape photo of the board from Part 4 with the oscillating regulators locations marked.

 

Offline Bud

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #149 on: March 18, 2016, 02:42:28 pm »
ah ah bud...this time i discovered this tweak just before you  ;)     the first mod i've done is a little heatsink on the adc... damn hot ! i could'nt put my finger on without burning first!  :'(
now its warm yes , but will not hurt anymore....
Next step, a silent fan !

Interesting, Emi. I mounted mine with the fins in vertical orientation. I believe I used Digikey p/n 294-1150-ND

 


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