Project Yaigol: Fixing Rigol scope design problems.

[Fungus]

I'm talking about The Keysight form Brazil (link you posted in this tread).

I'm just amazed you're defending Keysight here. If it was Rigol doing this you'd be going in with both guns blazing.

[wraper]

I'm talking about The Keysight form Brazil (link you posted in this tread).

I'm just amazed you're defending Keysight here. If it was Rigol doing this you'd be going in with both guns blazing.

I'm amazed I need to defend Keysight in Rigol tread because someone writes off topic BS in multiple treads.
I personally found some Keysight manufacturing fault in U1272A meter and created a tread in the past. And few people found the same issue in their meters (all got exchanged even without returning first).

[pascal_sweden]

Is there any overall write up or summary about the Yaigol project?

I am looking for something in the following structure:

1) Initial problem detected that seem to indicate a design issue
2) Investigation about the design issue
3) Confirmation about the actual design issue
4) Current impact of the design issue
5) Current firmware workaround for the design issue
6) Actual hardware fix for the design issue
7) Improved results after the design issue has been fixed in hardware
Scopes that are affected: Rigol DS1054Z, Rigol DS2072A?

[outremer]

   Hi all !

I spent hours reading this thread, redirected by tautech. I was impressed by the work of Bud. I'am planning to purchase a DS2202A. After analysing  the various contributions I came to the conclusion that the scope should just work according to its specs no matter if the spectral purity of its PLL output is perfect or not. If a firmware upgrade fixes the issue I will not look further. Poeple driving a Volkswagen diesel car have been more abused although the victim is the environment. This story is also good example to show how software gets more and more the determining factor in correcting design errors. See how the faulty  mirror of telescope Hubble was "repaired" (shoud I say repolished ?) with a bunch of code lines).

Regards, Phil FM5GB.

[German_EE]

The Hubble Telescope was repaired using a module called COSTAR which is about the size of a baby grand piano. Applying this fix required design, construction, delivery by Space Shuttle and two astronauts carrying out an eight hour spacewalk.

A bit more than "a bunch of code lines"

[Emi]

Hi 
After reading all these posts i still dont know how should  i test My ds2072 in order To confirm its "goodness " or not.
I put in a 1k Sine and its perfect and stable..so with 1mhz, 10, 100 and over 450 mhz...
Ive seen a complex  433 mhz Fm/pcm modulated signal from a radio remote control with stock probes too..perfecltly displayed. .i rally cant be disappointed with this stuff. .
 
How Can i really test all the above described  issues?
( i Mean at home .. without specific Lab instruments. .)

[Fungus]

the scope should just work according to its specs no matter if the spectral purity of its PLL output is perfect or not.

Exactly.

It's a clock. The only important thing about a clock is that it's regular.

The PLL design is messed up, but... it doesn't affect the results. That's probably why nobody at Rigol noticed it during testing.

Ive seen a complex  433 mhz Fm/pcm modulated signal from a radio remote control with stock probes too..perfecltly displayed.
How Can i really test all the above described  issues?

Maybe they're not really issues. Maybe it's just people on a witch hunt.

[German_EE]

"It's a clock. The only important thing about a clock is that it's regular."

Not true.

If an ADC is driven with a clock that has a poor phase noise then this will affect the output, the same applies to a DAC or a DDS chip.

If a clock signal has variations in amplitude then, in marginal cases, some of the clock signals will be missed leading to timing errors

If a clock is out of phase with the rest of the circuitry then this can lead to race conditions and data being latched at the wrong point

So, a good clock needs to be stable in frequency, have low phase noise, constant amplitude and be coherent with other signals on the PCB.

[marmad]

So, a good clock needs to be stable in frequency, have low phase noise, constant amplitude and be coherent with other signals on the PCB.

While all of that is true, nevertheless a DSO is just a tool. As long as it performs it's end tasks capably and without appreciable error - allowing me to do my job - that's all that matters. My hammer has a loose head, yet still I can pound nails with it.

People have been buying inexpensive test instruments with all kinds of wonky circuitry (overclocked ADCs, etc) and using it to get their jobs done for many years already.

[Monkeh]

My hammer has a loose head, yet still I can pound nails with it.

And one day that head's going to come off and cause you grief.

[marmad]

And one day that head's going to come off and cause you grief.

It would only cause you grief if you were naive enough to believe it would never come off. 

I have to think the OP didn't do much, if any, research into the level of design, manufacturing, testing, and quality components inherent in cheap Chinese test equipment before he bought his DSO. I don't buy a $1 hammer and expect a $20 one.

[Fungus]

My hammer has a loose head, yet still I can pound nails with it.

And one day that head's going to come off and cause you grief.

That's the problem with analogies - people can look for holes in the analogy instead of sticking to the main discussion.

A better analogy would be a hammer with a tiny crack somewhere deep inside the metal. It's imperfect, yes, but it hammers things just fine and there's no reason to believe it will ever do otherwise.

PS: If you own a hammer, how do you know it's perfectly cast? Does it scare you that there might be something wrong with it? Something down inside... 

[rstofer]

Is there any overall write up or summary about the Yaigol project?

I am looking for something in the following structure:

1) Initial problem detected that seem to indicate a design issue
2) Investigation about the design issue
3) Confirmation about the actual design issue
4) Current impact of the design issue
5) Current firmware workaround for the design issue
6) Actual hardware fix for the design issue
7) Improved results after the design issue has been fixed in hardware
Scopes that are affected: Rigol DS1054Z, Rigol DS2072A?

That's a lot to expect for a $400 scope!

There are two of these threads running and, after reading both, I suspect there may be some slight issues at the edges.  In other words, with stuff I am never going to use.  So I simply don't care!  Can I get 4 wiggles on the screen that bear some semblance to reality?  Sure!  And that's all I need.

There are about 4 people on the forum who are absolute Rigol haters.  No other way to describe them.  But here's the thing:  They won't sell off their Rigol scopes and buy something better.  They just continue to use the thing while simultaneously bashing it.  What's the sense in that?  They could dump the thing for $300 and spend the proceeds plus another $1000 or so and get a scope that's twice as good (maybe) at 3 times the price of the original Rigol.

Here's another thing:  You aren't going to get a $10,000 scope for $400.  If the minor (trivial) failings of the 1054Z will eventually cause you grief, buy something else.  Don't even look at the 1054Z.  Or any other Chinese scope, for that matter.  And don't expect that Rigol will ever fix the bugs.  That way you won't be disappointed when they don't.

It is what it is and it will never be any better than it is today.  If you keep that in mind, you won't be disappointed.  Or, throw in a whole lot more money and buy something better.

[nctnico]

People have been buying inexpensive test instruments with all kinds of wonky circuitry (overclocked ADCs, etc) and using it to get their jobs done for many years already.

That may be true but how many people will say 'gosh I wish I had bought this way better tool years ago because it is such a joy to use' after they got a quality tool instead of a low cost make-do POS? I'm sure the answer is many and it doesn't take a whole lot more money to buy a decent tool instead of something crappy. People just don't know what they don't know and often get blinded by what seems to be a good deal on paper but isn't in reality.

[marmad]

People just don't know what they don't know and often get blinded by what seems to be a good deal on paper but isn't in reality.

True, but then you have to ask yourself how much of the fault lies with the buyer? It doesn't take much research to see what the level of quality, workmanship, firmware development, support, etc. *can* be with Chinese-made test instruments. I would hope people without much money to spend do some research when spending a few hundred bucks on something.

And honestly, if you don't try to save every last little penny, you can usually give yourself a bit of 'buyer protection'. I personally never bought any Chinese-made test instrument that I couldn't return (except, of course, for things that cost less than € 50), so when I bought my first couple of Chinese DSOs - a Rigol and a Owon - I bought them from European distributors, which allowed me to return both of them for just shipping costs. Sure, I lost some money - but I was much happier with the DSO that I eventually kept.

[rstofer]

People have been buying inexpensive test instruments with all kinds of wonky circuitry (overclocked ADCs, etc) and using it to get their jobs done for many years already.

That may be true but how many people will say 'gosh I wish I had bought this way better tool years ago because it is such a joy to use' after they got a quality tool instead of a low cost make-do POS? I'm sure the answer is many and it doesn't take a whole lot more money to buy a decent tool instead of something crappy. People just don't know what they don't know and often get blinded by what seems to be a good deal on paper but isn't in reality.

And years later, if they really need an upgraded model, they sell off their lesser model and buy the newest thing on the market which will be far better than was available at the time of the first purchase (newer technology, larger screen, more measurements, etc).  In the meantime, they have used the scope for the difference between the buy and sell price.  Not all that much, I suspect.

Or, they never need an upgraded model.  In my view, it's better to get something and get started.  Interests change and there is no point in being overinvested in equipment. 

Yes, I do wish I had bought the Ferrari instead of the Porsche back when I was young.  That I might not have survived the experience is beside the point.

[Fungus]

People have been buying inexpensive test instruments with all kinds of wonky circuitry (overclocked ADCs, etc) and using it to get their jobs done for many years already.

That may be true but how many people will say 'gosh I wish I had bought this way better tool years ago because it is such a joy to use' after they got a quality tool instead of a low cost make-do POS?

a) The DS1054Z certainly isn't a "make-do POS".
b) At what price level do oscilloscopes stop being "make-do POS", in your opinion?

and

c) I really hope you never buy anything in real life, because there's always something better for more money. Always a better car, always a better house, always better furniture, always better clothes, always a better computer, always a bigger boat... how will you ever be satisfied?

[Fungus]

There are about 4 people on the forum who are absolute Rigol haters.  No other way to describe them.  But here's the thing:  They won't sell off their Rigol scopes and buy something better.

Yep, it's weird how they all own Rigols. It would be easy to sell them and buy $400 GW-Insteks instead, right? They'd probably get $300 if they sold their Rigols. So much suffering for the sake of $100, does it make sense to anybody?

[JPortici]

But if they didn't have rigols then they would be accused of
- being hypocrite
- not knowing what they talk about
- not keeping up with the update because you know you are comparing your system and you don't know nothing about how is it now do you

[Fungus]

It's not easy being a Rigol basher... 

[marmad]

Yep, it's weird how they all own Rigols. It would be easy to sell them and buy $400 GW-Insteks instead, right? They'd probably get $300 if they sold their Rigols. So much suffering for the sake of $100, does it make sense to anybody?

Actually, nctnico feels he got burned by being an early-adopter of the Siglent SDS2000.

Here's the thing: all of the inexpensive DSOs (Rigol, Siglent, Owon, Hantek, etc.) work perfectly fine in most respects, but tend to not work / have some bugs with / lack certain features in some area(s). If you plan on buying any of these DSOs, you have to reckon on the fact that those features / bugs may never get fixed. If those particular features are crucial for the work you do (I think they were in nctnico's particular case with the Siglent): don't believe promises from the manufacturers - look elsewhere for an inexpensive DSO. That's why it's a good idea to give yourself a chance to test any equipment with the option to return it.

[rsjsouza]

People have been buying inexpensive test instruments with all kinds of wonky circuitry (overclocked ADCs, etc) and using it to get their jobs done for many years already.

That may be true but how many people will say 'gosh I wish I had bought this way better tool years ago because it is such a joy to use' after they got a quality tool instead of a low cost make-do POS? I'm sure the answer is many and it doesn't take a whole lot more money to buy a decent tool instead of something crappy. People just don't know what they don't know and often get blinded by what seems to be a good deal on paper but isn't in reality.

An affordable "POS" can be seen as high quality in the hands of someone that never had access to such gear... Since technology advances at a fast pace, with the consequences for price/features, a purchase decision cannot be dissociated from the offers at the time. In other words, "quality" is very fluidly defined in terms of price, durability, features, bugs, cost of ownership (to name a few). For personal use the price and features have a heavier weight, while for business the durability and cost of ownership are more critical. That is why it is easier to make the statement highlighted when you make money with the tool.

Just to give an example, check my oscilloscope walk of life in this other thread. Given the current prices of used DSOX3000 oscilloscopes from Keysight, probably my decision to purchase the DS4014 would be different.

[scummos]

Very nice analysis and thanks for the writeup -- it was a fun read. It's indeed quite ridiculous Rigol doesn't even have a Lock indicator monitoring in place -- even my $100 hobby project displays an error message if the PLL fails to lock.

Here's the (in my opinion) interesting question, though: does this actually affect the scope's performance in a relevant way? Of course your ADC spectrum shouldn't look like that. But 50 kHz bandwidth over 1 GHz clock is something like < 1e-4 error. Most situations I can think of wouldn't have a single pixel changed in the signal display on the screen from that fault ...

[Fungus]

does this actually affect the scope's performance in a relevant way?

Nope.

(And I guess this is why the "problem" got past the development stage - there's nothing wrong on screen).

[wraper]

But 50 kHz bandwidth over 1 GHz clock is something like < 1e-4 error. Most situations I can think of wouldn't have a single pixel changed in the signal display on the screen from that fault ...

Yes it does, look at the DS1054Z video, with the quality of the clock in this particular BUD's scope, the same jitter problem should be present (but no SW fix).