EEVblog #675 - How To Reverse Engineer A Rigol DS1054Z

[LoyalServant]

I like it.... I have had to do some of this myself in the past and it really is tedious.
Of course we did not have nice digital cameras back then either.

I bet eventually they will stuff the whole circuit in custom silicon.... then you will need to do some nasty stuff to get at it.

[glatocha]

I am curious, what kind of precision they would use for the resistors in the AMP, Op amps feedback and so on. Would they go for 0.1% or even better?

[tecman]

A quick test - short B-E on switching transistors with a small jumper or solder blob, and measure BW with step input.  This should give you an idea of what the modes do.  When done, just remove the jumper or solder blob used to hold the transistors off.  Forget simulation.

paul

[Fungus]

I am curious, what kind of precision they would use for the resistors in the AMP, Op amps feedback and so on. Would they go for 0.1% or even better?

I'm guessing this is why they have a built-in calibration....to compensate for that sort of stuff.

[nixfu]

So if ALL FOUR of those filter caps are disconnected does that make room for a secret 200mhz model? 


After all, so far we only have 3 different 1000z models(50,70,100) and there are 4 possible combinations of the filters...hmmm.  Although I guess it would be just as possible to have a 25mhz model as the 4th combination of filters.

[BUkitoo]

Excelent Episode Dave!
By the way, Instead of get to paper different printouts, I use photoshop in different layers, and adjust them to match the holes.  .

[EEVblog]

I think you said 1052Z instead of 1054Z a few times in the video though.

Very likely!

[Robyn]

So basically: desolder 6 transistors, replace one with a short and you've got the 100MHz model. (per channel of course)

 I am not sure if that is an good idea. I think using the key is much better. If you use the DS at lower Samplerate I think its much better if it can reduce bandwith, because high frequencies above the Samplerate only make noise.


@Dave, Very much thanks for doing this video, it answered a question i was thinking about the last weeks. Thumbs up!

[Fungus]

I think you said 1052Z instead of 1054Z a few times in the video though.

Very likely!

I know he said it a few times. It's as if he still can't believe it's 4 channels.

[m100]

So if ALL FOUR of those filter caps are disconnected does that make room for a secret 200mhz model? 

Except that 200mhz is nearly DC   

[nixfu]

>Except that 200mhz is nearly DC

Yeah haha, Mega not milli.

200Mhz

[coppice]

>Except that 200mhz is nearly DC

Yeah haha, Mega not milli.

200Mhz

Participants in the pedants revolt need to make a better case than that. How about 200MHz?

Actually, 200MHz is pretty near DC for a gamma radiation expert.

[dentaku]

OK, so the question for a total newbie like me is... is this exactly the same hardware as what's inside the DS1074Z and DS1104Z?
All the features that can be unlocked on the higher end models are available to this model as well?

[Fungus]

OK, so the question for a total newbie like me is...

This topic has been discussed to death in the other threads.

(I wonder what other vital information you missed.  )

is this exactly the same hardware as what's inside the DS1074Z and DS1104Z?
All the features that can be unlocked on the higher end models are available to this model as well?

Yes

[David Hess]

I have doubts that the RE is correct!

I noticed the same two things you did.

1. The two top NPN in the DIFF DRIVER schematic get no positive base current.

If these were on the emitter side of the differential pairs instead of the collector, then they would form a linearized cross coupled quad which I doubt a high bandwidth vertical amplifier would need.  On the other hand, I would have expected a cascode on the output and they are in the right spot for it except for their base bias.

I see no thermal balancing on the collector side of the differential pairs.  Maybe that is what these transistors are actually doing?

The DS1000Z user guide does not say anything about separate position and offset controls and confusingly lists an offset range in the specifications but discusses vertical positioning so my guess is that the connection to the other side of the differential pair is for controlling the common mode level going into the ADC.

2. The DC-path from the input in the mode w/o attentuator only see 222k+265k instead of 1000k

Yep.  Something is missing or wrong here.  The input attenuator was obviously designed for a 1 Mohm input resistance.  I wonder how Rigol calibrated both the input capacitance and compensation with only one trimmer.  Maybe the manufacturing tolerances are good enough not to require it.

[Smokey]

Nice job on the RE.  I've done this with a two layer through hole board and a flatbed scanner and even that took forever and I didn't get it right the first time.

I was thinking of this earlier today....

If we were to put together a community schematic for something like this in a digital format, what program would we want to do it in?  Nothing against DaveCad, but there are some benefits to having a digital CAD copy from a readability and modify-ability standpoint now that the basic foundation is down.

My first thought was LTSpice since besides making a nice schematic you could potentially simulate it.  I know the bigger a schematic gets the harder it is to make the simulation work, but you could always break it up once it's all in there.  One more consideration is that all the parts would need functional SPICE models, which would mean a custom library for LTSpice which isn't really a show stopper.  Even without the simulation LTSpice would be a good clean free and accessible schematic capture.

Maybe treat it like open source software and store it on github or some other collaboration tool with an official maintainer?  That way people could get credit for contributing and finding mistakes and you could track the development.  I bet a fair number of people would benefit from something like that.

[dentaku]

OK, so the question for a total newbie like me is...

This topic has been discussed to death in the other threads.

(I wonder what other vital information you missed.  )

is this exactly the same hardware as what's inside the DS1074Z and DS1104Z?
All the features that can be unlocked on the higher end models are available to this model as well?

Yes

Other treads are full of useless arguing about stuff I don't care about that go on for multiple pages of bickering.
It's not what I'd call first time buyer friendly. Now that I know there's nothing special about the other DS1000Z models I know which one I want to buy.

edit...  just checked the forum thread for the teardown video and I see the question WAS answered in there quite a few pages in. I guess I didn't follow that one closely enough.

[EEVblog]

OK, so the question for a total newbie like me is... is this exactly the same hardware as what's inside the DS1074Z and DS1104Z?
All the features that can be unlocked on the higher end models are available to this model as well?

Yes.

[Fungus]

It's not what I'd call first time buyer friendly.

 

I guess there's a reason engineers don't usually make good shop assistants.

[dentaku]

 

OK, so the question for a total newbie like me is... is this exactly the same hardware as what's inside the DS1074Z and DS1104Z?
All the features that can be unlocked on the higher end models are available to this model as well?

Yes.

 

[dentaku]

It's not what I'd call first time buyer friendly.

 

I guess there's a reason engineers don't usually make good shop assistants.

They also don't make good customers because they get annoyed by the clueless people who work in stores.

[Fungus]

They also don't make good customers because they get annoyed by the clueless people who work in stores.

http://xkcd.com/806/

[steve_w]

Dave,

Love your work,

regards

Steve w

[Rasz]

Would be really nice if someone reverse engineered this (or one with similar performance) frontend properly, and released it as open hardware. I would gladly buy a module with 2 inputs at ~$50.

[David Hess]

Would be really nice if someone reverse engineered this (or one with similar performance) frontend properly, and released it as open hardware. I would gladly buy a module with 2 inputs at ~$50.

What features and performance would you expect from something like this?

Would you want everything up to the ADC or the ADC as well?  In this particular design the integrated ADC handles most of the gain switching so the front end is simplified.