Siglent SDS2000X Plus

[gf]

And now after this you can perhaps tell the fools why the sds2k+ can´t reproduce the signalform like the two chinese market only scopes before.
Is it because of a bug ( last time a FFT bug was fixed), is it because it can´t do it or is it because I´m to too dumb for the right adjustments.

I think it is a bug. The spectrum of the interpolated data does not look right. A sharp cut-off from the up-sampling filter (which is expected slightly below 1GHz) is missing in the spectrum. Instead, there is an (unexpected) cut-off at ~6GHz. Maybe just the scale is wrong? If the 6GHz point on the scale were marked with 1 GHz, then it might even look reasonable (considering the large amount of noise).

As I said before dV/dt is not a symbolic math function, but a numeric algorithm estimating from discrete data samples.
Key words here are sample density at the very fast edges ( and tendency of derivative to go to infinity when confused ) and  fact that it uses 4,8 or more points to calculate slope change for the derivative (depending on the setting). That alone means it is basically using low pass filtered data for the derivative calculation, effectively. I'm not privy to exact formula implementation so can't tell exactly. Will investigate.

Screenshot from handbook:


See also: https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg4160962/#msg4160962

[kcbrown]

I well recall Mike and found one of your old posts about the event. Yep I buggered the overlay too and should've used a hot air station for better heat control. 
Luckily our customer almost passes us to and from work so we'll get another overlay in a stock order for him.

I used a heat gun and a plastic razor blade to remove the overlay.  I set my heat gun to its lowest setting: 100 degrees C.  Worked a treat.  It did require a lot of care with the plastic razor blade to get it started, after which I pulled it up by hand once I had enough freed with the razor blade that I could get my fingers around it.

Because I figured I was voiding my warranty by opening the scope up anyway, I drilled out the holes that the screws fit through so that the screw heads would fit into the holes, and then secured the probe connector board to the frame using those screws before securing the front part of the enclosure to the frame.  With it set up this way, I'll no longer have to remove the overlay prior to disassembly.  There's plenty of structural connection of the front part of the enclosure to the frame, so the three screws that are underneath the overlay are not necessary for structural integrity of the front part of the enclosure.  Their use is only to firmly secure the probe connector board to the frame.

[2N3055]

As I said before dV/dt is not a symbolic math function, but a numeric algorithm estimating from discrete data samples.
Key words here are sample density at the very fast edges ( and tendency of derivative to go to infinity when confused ) and  fact that it uses 4,8 or more points to calculate slope change for the derivative (depending on the setting). That alone means it is basically using low pass filtered data for the derivative calculation, effectively. I'm not privy to exact formula implementation so can't tell exactly. Will investigate.

Screenshot from handbook:


See also: https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg4160962/#msg4160962

Thank you for quoting that, but I read that. I didn't mean we don't know what it should calculate. I said I don't know how it's implemented exactly in a code.. Devil is in details...  There are scopes that use only 3 points, for instance...

But as I said, I'll look into it.. While I didn't expect it to be accurate, it should provide ballpark curve....
Unless sampling rate + algo is not enough to see right at the edge of speed..

[gf]

For diagnosis about what...
...
In this example image, what this FFT tell about signal under test if we look this 0 - 25GHz  full span.

Please consider the aim, which was the diagnosis of a potential bug of the scope in conjunction with interpolation and FFT.
The 1...25 GHz region is indeed of interest if you want to assess the performance and correct functionality of the interpolation.

OTOH, I fully agree that this region is useless for the analysis of a signal under test if you presume that the scope works correctly.
[ With an ideal brickwall interpolation filter, cutting off at 1 GHz, this region were zero anyway, so what should it tell us then. ]

[tautech]

I well recall Mike and found one of your old posts about the event. Yep I buggered the overlay too and should've used a hot air station for better heat control. 
Luckily our customer almost passes us to and from work so we'll get another overlay in a stock order for him.

I used a heat gun and a plastic razor blade to remove the overlay.  I set my heat gun to its lowest setting: 100 degrees C.  Worked a treat.  It did require a lot of care with the plastic razor blade to get it started, after which I pulled it up by hand once I had enough freed with the razor blade that I could get my fingers around it.

Because I figured I was voiding my warranty by opening the scope up anyway, I drilled out the holes that the screws fit through so that the screw heads would fit into the holes, and then secured the probe connector board to the frame using those screws before securing the front part of the enclosure to the frame.  With it set up this way, I'll no longer have to remove the overlay prior to disassembly.  There's plenty of structural connection of the front part of the enclosure to the frame, so the three screws that are underneath the overlay are not necessary for structural integrity of the front part of the enclosure.  Their use is only to firmly secure the probe connector board to the frame.

Thanks for that info KC and I'll make a point of adding this into my writeup on a full X Plus disassembly....and of course with credits to thee !
Discussions today with the factory have them apologizing for not including a new vinyl overlay that they call a Channel Mask with the replacement mainboard. Apparently it's normal practice but somehow getting one to us was overlooked.

Edit
Dug out that post of yours I had been searching for:
https://www.eevblog.com/forum/testgear/new-electricalcomputer-engineer-student-test-bench-equipment-recommendations/msg4124305/#msg4124305

[BmaxTom]

Is it possible that the dx/dt (F1) function is not working correctly or is not calculating with the data displayed by C4? I think the maximum slope of C4 is not at -0.5ns but at 0.0ns.
Function d(Avg(C4))/dt (F2) fits better.
What I noticed while trying it out is that the formula editor always displays the last formula entered and not the current formula of function 1 or 2.

I checked the manual to see what d/dt is really supposed to do (see screenshot).
Do your F1 and F2 possibly use different dx for the finite difference approximation?

EDIT:

I find it actually a bit strange that delta t is specified in div units, where 1 div = 50 pixels.
(I'd rather expected to specify either number of samples, or seconds.)
And I also wonder whether 1 div = 50 pixels can be correct, if the screen has 10 div and screen width is 1024 pixels?

Sorry, was obviously an old version of the manual - the new one specifies dx in points.
Replaced screenshot. Still it sais 1 point = 0.01 div. So dx is still specified in 1/100 div units (and neither samples nor seconds)?

Sorry, dx was the same for F1 and F2.

[Martin72]

Today at work, bodnar on lecroy waverunner wr9354 500Mhz...
Martin

[kcbrown]

Thanks for that info KC and I'll make a point of adding this into my writeup on a full X Plus disassembly....and of course with credits to thee !

You're very welcome.  Since you're incorporating this into the writeup, there is one thing I didn't mention that I need to make explicit: when I was lifting the overlay ("Channel Mask") off by gently pulling up on the end (I had used the plastic razor blade to lift the edge up enough that I could grab it with my hand), I kept heat on the area of the overlay nearest the interface between the lifted section and the remainder.  Which is to say, I didn't merely heat the overlay a bit and then lift the whole thing off, but rather I kept heat on it as I lifted it off.  While the overlay might have come off anyway once I started it, I wanted to ensure that I didn't warp the overlay by applying too much force to it.  So I kept heat on it as I was lifting it off in order to minimize the amount of force I had to use to pull it away from the enclosure.

I think if it's done exactly right, you might not even need to replace the adhesive.  The chances are very good, however, that you will need to clean off the existing adhesive from the overlay and then replace it with new adhesive of your choice.  As mentioned in my original message that you found, I used transfer tape, specifically: https://www.amazon.com/467MP-Clear-Adhesive-Transfer-length/dp/B007Y7CV86

[gf]

@Martin72, I'd like to come back to one of your first attempts.
It failed due to a limitation of the d/dt function.
May I ask you to try that again with explicit interpolation, i.e.

- FFT(d(Intrp(C1))/dt)
- 20x interpolation
- dx as short as possible
- Flat Top window function
- span 0...1GHz
- 2µs/div (as before) might be a reasonable starting point.

[ Different from the "single impulse approach", this approach captures many 10 MHz square wave periods (the more the better). This does not give the transfer function directly, but leads to a sparse comb spectrum with 20 MHz spacing (odd harmonics of 10 MHz). However, the envelope of the comb is still (approximately) the transfer function. Due to a large number of samples, there is no need for averaging multiple traces (which also eliminates trigger jitter) -  instead the processing gain of the FFT will care about reducing the noise floor. ]

If the result is not plausible, then it may also suffer from from the previously seen issue with interpolation and FFT. But since the context is a bit different, Im not be sure that the same happens here as well

[Martin72]

Hi gf,

On the last two days I checked the thing at work on our lecroy scopes.
A WR9054, a HDO6034A and a WS3024Z or Siglent SDS3K...
On the forthcoming weekend, I´ll start a dedicated thread for it, including the results of my sds2k+.
I´m not very into it ( will be "corrected"), but actually I strongly believe there is a bug here.
Waverunner and HDO got two things in common, relatively to the siglent remarkable less memory, but lots of samples (20/10 GSa/s).
Wavesurfer got "less" samples and way more less memory.
Waverunner and HDO did the same like 2N3055´s scope, with FFT (C1(D/Dx).
Wavesurfer did the same like my SDS2K+....
Will be continued in a new thread.
Martin

[tautech]

SDS2000X Plus Teardown tips

Most guidance required can be found in the SDS2000X Plus Service manual in Chapter 6 Disassembly Procedures from P48 on:
https://int.siglent.com/u_file/document/SDS2000X%20Plus%20Service%20Manual_SM0102XP-E01A.pdf

Note, there are useful mentions of the number of screws to deal with at each stage and these help to reduce mistakes and confirm counts of fixings at each stage.

However, some color pics, specific tools required and a few hard earned tips never go amiss.
A single Torx T10 driver does most everything although it must be a long shank to reach all the rear cover screws. Tweezers and/or needle nose pliers are a must to manage screws as some are in recesses and prone to go walkabout into hard to access places. Stout long nosed pliers are required if you haven’t a 16mm deep reach socket for BNC socket nut removal and refitting.

On with the teardown…..this to replace the mainboard under warranty.
Getting to remove the mainboard is simple enough….just follow the Disassembly instructions however care must be taken with the ribbon cable connector for the front panel PCB.
It has a flip up latch that must be handled with care as to not break it and the next couple of pics show the latching mechanism open and shut plus the green hookup wire used to go fishing for the ribbon cable when it just won’t sit in an accessible position when refitting the new mainboard.

Encoder/keypad cable pics




There is just one other mainboard connection left, the double row socket with color coded wiring that includes some twisted pairs for the display driver board….another totally hidden surprise….more on this later.*
Removal of the mainboard first requires removal of the metal chassis it is mounted on so to access the 16mm fastening nuts on the BNC bulkhead fittings and you’ll already had to deal with 2 of these on the rear panel shielding and have found their tightness could be described as ‘just nipped’.
Removal of the mainboard chassis also entails removal of 3 hidden screws residing under what Siglent call the Channel Mask…..the adhesive vinyl overlay around the BNC inputs.

X Plus screws
Vinyl overlay X Plus




This is a properly awkward exercise and damage to the Channel Mask is very likely therefore a spare one should be ordered so to speed removal and reassembly.

Member kcbrown carefully examined the placement of these 3 hidden screws and formulated a modification to structural fixings so these 3 screws did not require access to remove the mainboard chassis from the scope front housing. See these posts:
https://www.eevblog.com/forum/testgear/new-electricalcomputer-engineer-student-test-bench-equipment-recommendations/msg4124305/#msg4124305
https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg4167997/#msg4167997

By now we should have the mainboard chassis removed but always keep referring to the Disassembly instructions for the little things that one can easily overlook.
Just a few more screws and the front panel can be removed to expose the encoder/keypad and probe sense PCB which must be done to access the BNC nuts.

Front PCB’s


Don’t forget to remove the additional 3 screws from the probe sense PCB so to access the BNC nuts and FG BNC nut.
BNC nuts


While here we need look underneath.
Rear probe sense.


With the mainboard now dead simple to remove from its chassis let’s have a look at the side of it that hidden from teardown videos.
Mainboard Underside


While we have it apart this far let’s have a deeper look at some things….
Apart


A couple of screws hold the encoder/keypad PCB on and the underside is here with ribbon cables back to the mainboard and to the probe sense PCB.
Underside encoder keypad PCB


*At this point we can see a small bundle of colored wires, some are twisted pairs going under the chassis to the display and that is unusual as display connections are normally ribbon cables. 
Just a few screws hold the display to the front of the chassis so at this point it would be rude not to investigate and it’s a good thing we did as the display PSU and driver PCB is not fully visible otherwise. Pic shows display backlight lead unplugged and its socket clearly visible.
Display driver


Reassembly is simple enough however 2 things in particular can be tricky, managing to keep the ribbon cable to the encoder/keypad PCB under control to have it accessible to plug into the new mainboard can be challenging and a plan to keep it under control or fish for it is worth developing.
Torx screw refitting management is challenging so to not have the little buggers get lost in the many crevices and spotting this standing out a mile had me devise a plan to keep control of them from the outset. These chassis fastening screws fix into the rear of the front panel, directly into the plastic and as the chassis they fasten is not very thick they tend to want to fall over and skate off to places unknown so with the tools at hand…tweezers and needle nosed pliers it was found needle tweezers held onto them really well but not like you might think…..the tweezer tips when trying to open held quite well enough to the inside of the Torx recess that it was possible to offer them to their position and wind them in a turn or so but after a reverse turn to have them drop into their previous fitting thread groove.

Tweezers


This all took a good couple of hours from start to finish with the tablet alongside for the frequent referrals to the Service manual. Best advice is don’t hurry and take a few pics to refer to for reassembly.

[tautech]

Additional pics and some info and pics on 50 Ohm inputs to come in another post.

[tautech]

50 Ohm input damage info.

Any input overload damage to the 50 Ohm input circuit is apparently likely to be limited to the two 24.9 Ohm resistors, contacts on the 50 Ohm relay and possibly one inductor in the circuit.
See attached doc for official rework documentation.

Some pics
Topside relay closest to BNC and 24.9 Ohm size 1210 resistor are both possible damage points.


Bottom side 1210 24.9 Ohm resistor.

[mawyatt]

Intersting, thanks for showing.

Question: Why would Siglent use two 24.9 ohm resistors in series rather than two 100 ohm in parallel? Seems the parallel combo would produce a better overall desired 50 ohm result with a less imaginary result.

Best,

[Johnny B Good]

@tautech,

 Many thanks for all those pictures and additional notes on disassembling an SDS2000X Plus.

 I remembered that I'd grabbed all of Siglent's documentation on this model when (or even before) I'd purchased it about a year back actually almost two years ago now, so checked out the service manual (SM0102XP-E01A). I'd briefly skimmed through it at the time but didn't bother with a more thorough study of its contents (why bother when you might well have sold it on or bequeathed it to your descendants before the need for such servicing or repair ever arises?).

 Taking another look at the manual to relate your observations about its incompleteness over some of the finer details (it glosses over the need to peel away the channel ID sticker for example),  I spotted another missing detail in the acquisition board testing where it referred to the PSU's "Standby voltage" when referring you back to the PSU check which begs the question, "Which of those rail voltages is the SB rail?

 Other than some minor shortcomings, it's a decently written service manual worth having to hand, even if the illustrations leave something to be desired. Your actual photographs are a great boon in that regard and I'm very grateful to you for taking the time and trouble to publish them here even though, with luck, I may never need to consult them or the service manual ever again.

 It's just comforting to know that should the occasion were ever to arise, I'll at least have a fighting chance of effecting my own recalibration or repair at a minimal cost of just replacement parts.

[kcbrown]

Other than some minor shortcomings, it's a decently written service manual worth having to hand, even if the illustrations leave something to be desired. Your actual photographs are a great boon in that regard and I'm very grateful to you for taking the time and trouble to publish them here even though, with luck, I may never need to consult them or the service manual ever again.

I figure that because I went to the trouble of drilling out the holes behind the "channel mask" so that I'd never have to remove the mask again, I won't ever have to open up the unit to that degree again. 

[oewean]

New firmware for SDS2000X Plus
5/23/2022 1.3.9R12 1. Fixed several bugs of 1.3.9R10
a) Compatibility issue on 2-channel models
b) WebServer control issue

https://www.siglenteu.com/service-and-support/firmware-software/digital-oscilloscopes/#sds2000x-plus

[maxspb69]

It makes no sense to install this firmware ... for most owners. Probably

[ozkarah]

My device came with V1.3.9R10. I had the webserver control issue.
 I was able to see the scope screen on the web page (or using a VNC Viewer), keyboard was also working but mouse wasn't.

Just upgraded to V1.3.9R12. Now the mouse works fine on the web page and on the VNC Viewer 

Bandwith and other option upgrades are also okay. No new issues yet.

[Martin72]

Short heartstopping after the upgrade...

After "reboot", both usb-ports won´t work anymore, no supply for the bodnarpulser, no detection of the usb-stick..
Turn the scope off, then on...both ports are avaible again   
FYI.

[Martin72]

Today our three sds2104X+ arrived at last from external calibration.
Every scope passed it flawless without issues. 

All three are very close together so I´ll upload one calibration report - After some edits ( erasing company name, serial number, etc)..
Below a part of the channel vertical measuring, for me the results are very good.

Martin

[trp806mo]

Just for information, I bought a new SDS2104X+ (version 04.05 / FPGA version 2022-02-08) and the .py is still working ... but I encounter my first freeze during the boot with the Siglent logo which doesn't disappear By following the attached procedure I was able to fix it and the first try was ok.

[alocam]

BTW, what is the folder comparison tool that you use? Looks like it has plenty of features.
Regards! 

[Martin72]

All three are very close together so I´ll upload one calibration report - After some edits

Converted pdf to word and back, maybe there are some viewing issues..
But here we are, see below and time limited.

Martin

[Johnny B Good]

 Thank you very much Martin for posting those calibration results.

 Just one question: were these the Factory Calibration test results or the results after re-calibration?