Author Topic: Project Yaigol: Fixing Rigol scope design problems.  (Read 79640 times)

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Offline Nuno_pt

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #100 on: March 16, 2016, 11:07:22 pm »
The more difficult part will be the two wire ohm alike, for those that don't have an VNA to measure the OHm range at 1GHz.

The rest till now would be pretty strait forward.
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Offline Emi

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #101 on: March 17, 2016, 12:14:16 am »
Right...that coils seems quite tricky to build and put in correctly and are really a critical step. . What's wire exact diameter? 0.25mm ?  And precise orienting?  :o
« Last Edit: March 17, 2016, 12:40:39 am by Emi »
 

Online Bud

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #102 on: March 17, 2016, 01:32:12 am »
, I would expect it would be an easy court case to prosecute in the UK's small claims courts.

Take it easy guys, it is not worth your time and sweat drugging a spectrum analyser into the courtroom
 ;D
 

Offline c4757p

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #103 on: March 17, 2016, 01:38:44 am »
, I would expect it would be an easy court case to prosecute in the UK's small claims courts.

Take it easy guys, it is not worth your time and sweat drugging a spectrum analyser into the courtroom
 ;D

Yes, please. Everything has design flaws, complaining about them is one thing, but we don't need to make the legal system profit unnecessarily over them ::)
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Offline miguelvp

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #104 on: March 17, 2016, 01:42:09 am »
Not only that, but Rigol only has to show that their equipment meets the specs published.

So far I haven't seen that not being the case, or did I miss something that shows either the DS1000 or the DS2000 not meeting their claimed specs?
 

Online Bud

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #105 on: March 17, 2016, 01:44:03 am »
#30 converts to 0.254mm, some +/- should be ok, i used two different wire thicknesses from the spools i happened to have. Solder them in rabbit ears fashion ( V- shape) and it should work fine. Again, you could search for and buy two 3nH smt inductors, 0603 size and i recall 0805 can also be fitted, since it is required to solder them at right angle a short extension wire is needed to connect one terminal of the right angled inductor to the second solder pad. The pads on the pcb are too small for a repositionedinductor to be soldered directly to them.
 

Online exe

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #106 on: March 17, 2016, 01:45:48 am »
Hi Bud,

Nice work! If you still have the scope, could you please post a picture with the "new" noise floor? I'm curious if it is any better.

PS I can't believe how far they got wrong with LDOs and ESR... I suspect there many more surprises inside. But I got it, you've seen enough and now selling the unit.
 

Online wraper

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #107 on: March 17, 2016, 01:47:06 am »
They will have weighed up everything along the way and risk assessed whether they should have done anything about it.

Probably.

One thing that will get their attention is if their distributors find they are having to sort out complaints and court cases from customers.

IANAL, but given Bud's report, I would expect it would be an easy court case to prosecute in the UK's small claims courts.
Prosecute for what? Scopes are working. Good luck to prove that oscillating LDOs makes the scopes being faulty. All you can claim that you are offended by the ripple on power rails  :-DD.
« Last Edit: March 17, 2016, 01:51:13 am by wraper »
 

Offline c4757p

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #108 on: March 17, 2016, 01:58:29 am »
PS I can't believe how far they got wrong with LDOs and ESR... I suspect there many more surprises inside. But I got it, you've seen enough and now selling the unit.

That LDO is one made by many manufacturers, and all are subtly different. I bet they used one in prototyping that was perfectly happy in that circuit, then switched to a different (less expensive?) vendor for production. Could be a decision made by the bean counters, few of whom would realize the potential issue there. It still works, so nobody noticed the problem.
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Online Bud

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #109 on: March 17, 2016, 01:58:57 am »
@miguelvp

Questioning of claimed specifications was never in my mind. If i happened to buy a 4 cylinder car with only two cylinders working and the car seller speck-d the car fuel consumption and engine performance based on two cylinders, then the specs are technically correct and it does not make sense to claim otherwise even if i went and fixed the other two cylinders.
 

Online tggzzz

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #110 on: March 17, 2016, 02:12:55 am »
Not only that, but Rigol only has to show that their equipment meets the specs published.

Not in the UK. You only have to show the design was defective, and proportionate damages will then be awarded. Of course, what "proportionate" means will vary from owner to owner and court to court.

It is also and entirely separate issue as to whether it is worth an owner going taking any action whatsoever.

I wonder how many people suffered damage from the Pentium FDIV bug? Nonetheless, Intel took prompt and praiseworthy action in that case, and Intel's reputation was enhanced.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline miguelvp

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #111 on: March 17, 2016, 02:16:57 am »
PS I can't believe how far they got wrong with LDOs and ESR... I suspect there many more surprises inside. But I got it, you've seen enough and now selling the unit.

That LDO is one made by many manufacturers, and all are subtly different. I bet they used one in prototyping that was perfectly happy in that circuit, then switched to a different (less expensive?) vendor for production. Could be a decision made by the bean counters, few of whom would realize the potential issue there. It still works, so nobody noticed the problem.

That's a common problem, cost reduction gets designs altered in many products and it only requires someone to sign off on it that might not even be the original designer.

Same thing happened to Jeri Ellsworth on her C64 Direct to TV joystick
https://en.wikipedia.org/wiki/C64_Direct-to-TV

Not sure where I've heard it but pretty much she had to fly to China because the devices were not working, just to find out that cost reduction had altered her whole design, so she had to find a way to make it work while it was in production.

She will be the first one to tell you that the resulting device was a POS, but it was produced with low cost in mind, so it ended up to be what it ended up to be.


 

Online tggzzz

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #112 on: March 17, 2016, 02:21:27 am »
, I would expect it would be an easy court case to prosecute in the UK's small claims courts.

Take it easy guys, it is not worth your time and sweat drugging a spectrum analyser into the courtroom
 ;D

Yes, please. Everything has design flaws, complaining about them is one thing, but we don't need to make the legal system profit unnecessarily over them ::)

The legal system wouldn't profit in the UK's small claims court - it is there to get swift cheap justice. No legal representatives are necessary, and plaintifs normally represent themselves. If the defendent wishes to employ lawyers, that is up to them.

It is an excellent mechanism for keeping small claims out of the legal system. Legal costs are not awarded to the loser - which is an excellent incentive against rich defendents trying to intimidate people by spending large amounts of money on lawyers.
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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Offline c4757p

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #113 on: March 17, 2016, 02:22:44 am »
Minor nitpick, the point is the system doesn't have to be involved in this at all. I don't actually care about the specifics of how your legal system works.
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Online tggzzz

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #114 on: March 17, 2016, 02:28:19 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.
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 wraper

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #115 on: March 17, 2016, 02:30:42 am »
Have not checked yet if there is an oscillation, but all 1117s in my non- A DS2072 are not NCP1117 from ON semi but from some different manufacturer which I'm unable to recognize.

« Last Edit: March 17, 2016, 02:32:51 am by wraper »
 

Offline c4757p

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #116 on: March 17, 2016, 02:37:52 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.
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Online wraper

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #117 on: March 17, 2016, 02:47:05 am »
... And there isn't any LDO oscillation in my scope.
 

Offline Nuno_pt

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #118 on: March 17, 2016, 02:50:09 am »
Have not checked yet if there is an oscillation, but all 1117s in my non- A DS2072 are not NCP1117 from ON semi but from some different manufacturer which I'm unable to recognize.

It could be from Taiwan Semi.
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Online wraper

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #119 on: March 17, 2016, 02:54:19 am »
Have not checked yet if there is an oscillation, but all 1117s in my non- A DS2072 are not NCP1117 from ON semi but from some different manufacturer which I'm unable to recognize.

It could be from Taiwan Semi.
I checked those already, marking does not match with the datasheet.
 

Offline marmad

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #120 on: March 17, 2016, 03:04:34 am »
Questioning of claimed specifications was never in my mind. If i happened to buy a 4 cylinder car with only two cylinders working and the car seller speck-d the car fuel consumption and engine performance based on two cylinders, then the specs are technically correct and it does not make sense to claim otherwise even if i went and fixed the other two cylinders.

That seems rather a false equivalency. If you buy a 4 cylinder car, you expect the specs to be based on all 4 cylinders. In what way are you suggesting that Rigol is juking their specs?

I've been using my DS2000 to make money freelancing for 3.5 years without any measurement errors or faults causing me problems  - and with no service issues except for an encoder that died (and was replaced under warranty). While I'm finding your investigation and tweaking of the hardware fascinating, the issues you've discovered - at least in my unit - have had zero effect on my usage of the DSO.
 

Offline Emi

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #121 on: March 17, 2016, 03:08:05 am »
Oppsss ..One more  stupid question, forgive me ...
....
which  esr value is better  in these tantalum caps?
Around 0.5 ohms  or even  higher ( 1  or more ..)

 

Offline uChip

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #122 on: March 17, 2016, 03:12:14 am »
@Bud
Thank you for your excellent efforts.  I recall you criticizing the PLL when the jitter problem was first discovered.  I think your findings prove without a doubt that your criticisms were all correct.  The PLL fail cannot be blamed on building down to a price point. Since you changed only component values, I doubt you impacted manufacturing cost at all in the PLL circuit and by no more than a few pennies overall.  The tantalums are a bit more expensive but I'll bet that with sufficient effort an equivalent cost solution could be had.  There is no excuse for Rigol not to have gotten this right.  I do agree with what folks said about translation from engineering to production.  I've experienced that myself.  It could explain the wrong ESR caps on the LDOs, but not the wrong values on the PLL.

One thing, most of us do not have the SA to confirm our fixes.  We would be doing it blind and taking it on faith that our scope performance was improved.  Replacing caps is relatively easy, but those hand-fabricated inductors are likely beyond me.  It would be of benefit to many, I think, to swap back to chip inductors of the proper value and retest.

@IanJ
Great opportunity for a "repair" video!  I've really enjoyed to ones you've done before.  If you do it there are several places that you could add value.  One, if you have a 1054Z it would be good to perform the fixes and IDing the component locations on that model.  Two, you could use chip inductors instead of hand fabricated.  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.

@The folks who question the value of the fixes
I agree with the person who said that ripple is not likely to cause crashes.  By its nature digital logic is fairly robust.  It's far more likely that crashes are caused by flawed software.  Besides, the LDOs Bud fixed were for analog circuits.  The impact of those would be things like offsets just as Bud wrote.  Also things like trigger sensitivity and dare I hope that cleaning up the supplies would improve the noise floor.  I would love to see before and after captures of a 10 MHz 2 mV signal.
 


Offline marmad

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Re: Project Yaigol: Fixing Rigol scope design problems.
« Reply #124 on: March 17, 2016, 03:44:51 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?
 


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