Need help! Test bench equipment recommendations. $2k+ budget

[egonotto]

Nowadays you can buy decent differential HV probes for less than $200 (the ones from Micsig for example) and sometimes good deals come along as well.

......

Getting good bandwidth and 10X signal reduction is going to cost you, near as I can tell.  Examples to the contrary would be welcome.

Hello,

perhaps Micsig DP10007
https://www.batronix.com/versand/messtechnik/tastkoepfe/Micsig-DP10007.html

Best regards
egonotto

[bdunham7]

Getting good bandwidth and 10X signal reduction is going to cost you, near as I can tell.  Examples to the contrary would be welcome.

Don't forget CMRR and noise.  The Sapphire-built probes are still a decent choice, the EEVBlog one is actually a good deal at $450 AUD. 

[kcbrown]

If the original encoders weren't working then this is exactly what I would do.  Swapping A with B is sufficient to yield the desired result.  But it appears that won't be necessary.

Well, this turned out to be wrong.

I put the original encoders back into play and the issue with the scope missing my inputs returned.  So it is the encoders, but it's not that they're not generating output.

This can mean only that the encoders aren't reliably generating pulse widths wide enough, or enough time between A and B, to make it possible for the scope to reliably recognize that the encoder has been moved.  I suppose it's possible that the internal impedance of these encoders is just high enough to ride that threshold.  I'll have to measure that.

So now I'm going to try reverse the pins on the replacement encoders.  This is not easy to do with the amount of room that's available.  It's finicky work.  I'll post another update once I've completed that work (the scope is apart at the moment).


To those who have an SDS-2kX+: if you've got the waveform up on the screen, and you turn the timebase encoder one detent, does the scope reliably see your input?  Mine doesn't with the original encoders but does with my replacements.  If yours doesn't, then we have a more widespread issue than just mine.

[bdunham7]

Mine doesn't with the original encoders but does with my replacements.  If yours doesn't, then we have a more widespread issue than just mine.

Mine responds to each and every click of the knob unless I turn it very quickly, so quickly I can't keep count.  I can adjust it 10 clicks one way nd then 10 back with my eyes closed and it ends up where I started.  I find that the best way to describe Siglent UI and encoders is that I tend to carefully watch the instrument as I change the settings--it isn't one of those you can reliably do quickly or by feel.  However, I can not find any of the complained-about defects in any of my instruments and the SDS2104X+ seems solid to me so far.

[kcbrown]

An update: I installed my replacement encoders with the outputs cross-connected (this was annoying to do.  I'm fortunate that I had silicone-sheathed wires to do it with) and it works a treat!

Unfortunately I forgot to get pictures of it, but I do have an encoder that I used to test the idea with and I can take a photo of that if anyone's interested.   There's relatively little space to play with because the buttons are fairly close to the encoders, so I had to minimize the wire length and ensure that the wires had sufficient insulation to not contact the common pin and ensure that they were short enough to stay within the allowed volume region for the encoders.

Mine responds to each and every click of the knob unless I turn it very quickly, so quickly I can't keep count.  I can adjust it 10 clicks one way nd then 10 back with my eyes closed and it ends up where I started.

This suggests that Siglent made a hardware change.  It would be interesting to know if your encoders are the same as the ones that were originally in my scope.  I suspect not.  Opening the scope enough to get to the encoders is more trouble than it's worth, though, even if yours happens to be out of warranty, so I can't exactly ask you to check. 

With my replacement encoders in place, my scope behaves as yours does.

So this is very definitely an encoder issue, and very definitely not an issue with the solder joints or any of that.  The fact that both of the original encoders show the same patterns on the scope means that this isn't a production defect in the encoders, but a design defect.

I'll play with them and see if I can characterize them better.  Maybe something will stand out as faulty once I post up the various waveform characteristics of them.

[kcbrown]

So this is very definitely an encoder issue, and very definitely not an issue with the solder joints or any of that.  The fact that both of the original encoders show the same patterns on the scope means that this isn't a production defect in the encoders, but a design defect.

I'll play with them and see if I can characterize them better.  Maybe something will stand out as faulty once I post up the various waveform characteristics of them.

Well, I did exactly this, and it is indeed a bad encoder after all.  I don't know how I missed this before.

Here's the encoder output from the bad Siglent encoder:



Here's the encoder output from the good Siglent encoder:



And here's the output from the Bourns encoder:



As you can see, the output from the bad encoder is horribly noisy.  This is with the debounce circuitry as shown in the Bourns datasheet, which has the output pin connected to a 10 pF capacitor in series with a 10K resistor to ground (and also has the output pin connected through a 10K resistor to +5V, and common to ground, so you get an active low circuit as seen in the above screenshots).  No wonder the scope didn't detect my inputs from it.  No matter what, I'd have had to replace it.  Just as well that I replaced both.

You can also see how the inputs from the Bourns encoder are reversed in phase compared with the Siglent encoders.

[tggzzz]

Here's the encoder output from the bad Siglent encoder:

Here's the encoder output from the good Siglent encoder:

I had a "noise" problem with a rotary encoder on a bench PSU. Thorough rinsing with IPA was sufficient to clean out whatever was causing the problem.

[kcbrown]

Here's the encoder output from the bad Siglent encoder:

Here's the encoder output from the good Siglent encoder:

I had a "noise" problem with a rotary encoder on a bench PSU. Thorough rinsing with IPA was sufficient to clean out whatever was causing the problem.

Oh, wow.  That worked fantastically.

If I ever need to replace these encoders again, I'll have ready-made replacements.   


EDIT: Well, it worked temporarily.  But the noise issue came back after it sat overnight.  So I dropped some DeOxit into it and we'll see how long that lasts.

[kcbrown]

EDIT: Well, it worked temporarily.  But the noise issue came back after it sat overnight.  So I dropped some DeOxit into it and we'll see how long that lasts.

Nope, that also came back after it sat overnight.

So I guess this encoder's basically done for any sort of production duty, at any rate.

[kcbrown]

How strong is the adhesive in those?  Remember that the goal is to make it possible to peel the sticker off of the scope by hand without damaging it, so as to make it relatively easy to remove the front plastic panel if that should prove necessary.

Pretty strong but it depends on the surface substrate how well they hold together.
The large dispenser gun we stick light card nonglossy business cards to catalogues with a single 20mm strip of glue and they won't come off without one or the other tearing or delaminating.
Years ago I used it to stick a 1/4" glass pull tab to a sliding glass panel and it stayed put and worked great whereas a previous one stuck down with epoxy stressed the glass and it broke.

Flexy vinyl label to thermoplastic housing I would have no hesitation like for X+ however I do know you can get the sticker in question from Siglent NA as member mwyatt needed one for his X+ when it had an accident with liquids and he had to fully strip and wash it to recover it.

It turns out that I wound up solving the problem a bit differently than others might have.  I noticed that there were other screws that attached the input board to the frame and which were behind the front plastic section that the label applies to.  It turns out that this plastic section has a taper to it such that there's no distance between it and the input board at the bottom but there's some distance between it and the input board at the top, just enough for the heads of the screws at the top of the input board to fit behind.   This fact caused me to look at how the front part of the housing was mounted to the frame, and to see whether the screws that sit behind the label are necessary for structural integrity.  They're not, really.

So I drilled out the holes in the front plastic section that those screws go through, such that their heads would be able to fit within the resulting widened holes, and then used those screws to attach the input board to the frame directly before attaching the front housing to the frame.

I then used transfer tape on the back of the sticker, and carefully cut around the periphery of the sticker as well as the holes in the sticker, peeled the backing paper off, and then very carefully applied the label to the scope after it was fully assembled (after cleaning the area it was being applied to with IPA).

The end result looks like I never took the thing apart.  I'm very pleased with the result.  The stuff is sticky enough that the label isn't going anywhere and with the alterations I made, I can disassemble the scope at will without having to worry about the sticker at all.

If you ever decide to take your scope apart, I highly recommend re-assembling as described above so that you don't have to fool with the sticker ever again.

[geneonline]

Thanks for the detailed write up and solutions! It has been a couple of months already and everything works really when and has been coming handy when doing experiments and testing at home. No issues with the encoders or dials on the silent oscilloscope. Feels smooth when using. Fairly responsive for my use cases. It just takes a minute to find features and functions in menus. Just will take time getting used to the locations. Cant thank you all enough getting me set up! May add a function generator this semester as I need to simulate AC currents different wave forms and measuring how different components effect the signals like phase shifts.

May also invest in a bench DMM to help with log term monitoring and easier use. Not stressing about what to choose for these items as there is a lot of charts and fairly reliable for my remaining school/home projects.

One thing I'm very curious about is a highly versatile 3-D printer to begin bringing ideas to form. I know of the basic filament material but not sure which would be good for the higher quality like abs filaments as I've already made a few things with PLA. Looking for stronger and lighter material.