Siglent SDG1032 as bad as rigol DG812?

[eTobey]

Only one feedthrough 50Ohm terminator was used at CH1 of the scope, were the square wave was applied.

Which one exactly?

[Mortymore]

Only one feedthrough 50Ohm terminator was used at CH1 of the scope, were the square wave was applied.

Which one exactly?

The terminator? No brand. Does it matter for a low frequency signal?

[eTobey]

Only one feedthrough 50Ohm terminator was used at CH1 of the scope, were the square wave was applied.

Which one exactly?

The terminator? No brand. Does it matter for a low frequency signal?

Probably not, but i might want to buy one ;-)

[Aldo22]

Probably not, but i might want to buy one ;-)

You can make one yourself to start with.
I made one from 2x100Ω  SMD.
Certainly not perfect, but much better than without (attached images).
Or something like this: https://de.aliexpress.com/item/1005005986180797.html

[KungFuJosh]

I have a couple Rigol ADP0150BNC. Which will probably be the only Rigol gear I ever own. 🤣

[Sensorcat]

I have a couple Rigol ADP0150BNC. Which will probably be the only Rigol gear I ever own. 🤣

Usually not needed. Many people think a 50ohm termination is necessary to avoid errors due to reflections at oscilloscope inputs. But this is only true if you use regular coax cables to the scope inputs. Up to several hundred MHz, the best thing you can connect to these inputs is a good 10x probe instead. Its cable is not a regular coax, but a special lossy transmission line, which effectively solves the problem at no additional cost, since you need these anyway. If you have some sort of coax wiring on your desk, with BNC connectors, all you need is a BNC probe tip adaptor. A cheap and easy solution, which does not require external terminators (which are accesories offered quite often in low quality), and no internal termination (which restricts the choice of scopes to expensive models).

Best source I know to explain the details: https://cleverscope.com/downloads/articles/THE_SECRET_WORLD_OF_PROBES_OCt09.pdf

[KungFuJosh]

I have a couple Rigol ADP0150BNC. Which will probably be the only Rigol gear I ever own. 🤣

Usually not needed.

Indeed, especially considering my SDS2504X+ has 50Ω inputs when I need it. However, they have come in handy a few times over the years. The quality of them seems fine for what they are.

[Sensorcat]

Indeed, especially considering my SDS2504X+ has 50Ω inputs when I need it. However, they have come in handy a few times over the years. The quality of them seems fine for what they are.

Another advantage of the 10x passive probe everybody has is the DC load: You can avoid reflection issues and have input resistance of 10MΩ at the same time.

Good for you if you have 50Ω inputs. My intent was to write something useful for those who don't.

[KungFuJosh]

Another advantage of the 10x passive probe everybody has is the DC load: You can avoid reflection issues and have input resistance of 10MΩ at the same time.

Good for you if you have 50Ω inputs. My intent was to write something useful for those who don't.

Thank you. 😉 Anyway, sometimes simple coax is the correct choice, and those individuals without the 50Ω inputs will need the terminators.

[Njk]

What you see in the screenshots is typical for less than optimal power-supply sequencing at power down.

Definitely. Looks like the power good signal from PSU is missing or the sw pays little attention to it. It's impossible to specify everything by formal requirements. But customers typically assume that the designer is from the same planet.

[rf-loop]

Are you referring to some overshoot when the generator is turned OFF with the outputs still on, right?

It seems that it could happen depending were the square wave is caught at power off. Sometimes it doesn't happen, sometimes overshoots up, other down.



Anyway, I suppose that the ON/OFF output buttons serves a purpose, and that doesn't happen when they're used

EDIT: It would be so much easier for everybody if at least you had the trouble to proper stand your case with adequate description and images. After all you have the devices.

I want look this bit more when I have time for it.
If it is very "random" after shut off with power line, I want still catch it (these upper level "peaks" in end.)

The signal outputs should be cut off before the collapse of the operating voltages progresses to a level where the device starts to run out of control.


How was signals connected. (in your image looks it looks like well connceted with external 50 ohm and coaxial but still I like facts and not my quess.)
What is your SDG Hardware version.

Hi rf-loop

The AWG is an SDG1032X (upgraded to SDG1062X), SW version: 1.01.01.33R8 ; HW version: 02-01-00-24-00
The cables used are a very old pair of RG-58/CU with 1m aprox.
Only one feedthrough 50Ohm terminator was used at CH1 of the scope, were the square wave was applied.

The over and undershoot captured in previous images, doesn't always happen. I could have posted a similar picture as yours, but it would have been redundant.
I assume that the "spikes" seems to be controlled somehow, because there are flattops, when a differential voltage goes over roughly 1.5V.

If any further info or diligence from me is needed, please inform.

I have now been testing this phenomenon for several hours repeatedly, last evening and continuing today. I haven't counted the repetition times, but I estimate at least more than 200. I also did experiments with different frequencies, amplitudes and offsets. I have never seen anything similar that appears in your picture right when channel 1 ends. Those nearly 2V spikes.

Each time I have seen a quite nice landing.

My HW version is the same as yours.
I run FW version .33R1 because I have modulation and ramp etc. modifications that should be done again if I update. There are more important things to do, so I'll update sometime later if necessary. I also can't really believe that this would affect exactly this behavior when the operating voltages start to drop when the power goes OFF.


It is actually impossible to completely prove that something does not exist.

Besides, even though the HW version is the same, there are still differences, in fact in every component. (for example, if one were to examine very carefully at which point the relays related to the output stage of the signal change state after PowerOFF when all power supplies voltages start fall, time differences will certainly be found.)

[eTobey]

I got:
FW: 1.01.01.33R8
HW: 03-00-00-24-00

High level 3.3V, Low level 0V

And almost 3V of "limit overshoot".
And a mean of 4.5V for 240us

[rf-loop]

@Mortymore

Here just one random result during this PowOFF test.
Yes there are some small differences with different frequencies, different levels and offsets etc...

In this image full max voltages with HiZ loads. Ch1 1kHz, 20Vpp and Ch2 (scope Ch4) 10Vdc
(signals connected directly using 50ohm coaxials)

Least with my unit there can not find problem in output signals when hard PowOFF.
But naturally my predictable rest of lifetime is not enough for test every possible setup combinations even once per setup. 

[eTobey]

But naturally my predictable rest of lifetime is not enough for test every possible setup combinations even once per setup. 

If you would choose  a 100mHz square, and a 99% duty, you are more likely to hit that high level right at the beginning of the rest of your life.

On that picture it looks like you hit that low level... 

[rf-loop]

But naturally my predictable rest of lifetime is not enough for test every possible setup combinations even once per setup. 

If you would choose  a 100mHz square, and a 99% duty, you are more likely to hit that high level right at the beginning of the rest of your life.

On that picture it looks like you hit that low level... 

That one magpie's nest type of signal connection that you recently brought up when you criticized the generator's frequency response. I will say one more and one last time. Most of the problems you'll encounter with oscilloscopes or generators are between them and the chair you sit. Next time I might say it less nicely.

Here is 100mHz and 99% Duty. And again hard PowOFF.
And yes, signal is 20Vpp and other is generator 10V DC out (also for trig)

[eTobey]

But naturally my predictable rest of lifetime is not enough for test every possible setup combinations even once per setup. 

If you would choose  a 100mHz square, and a 99% duty, you are more likely to hit that high level right at the beginning of the rest of your life.

On that picture it looks like you hit that low level... 

That one magpie's nest type of signal connection that you recently brought up when you criticized the generator's frequency response. I will say one more and one last time. Most of the problems you'll encounter with oscilloscopes or generators are between them and the chair you sit. Next time I might say it less nicely.

Here is 100mHz and 99% Duty. And again hard PowOFF.
And yes, signal is 20Vpp and other is generator 10V DC out (also for trig)

If you set up values, that are far away from those that showed the issue, and want to compare, you also have a problem between the chair and the screen.

[TurboTom]

If you want to be sure that you won't overload your digital circuitry's input (Microprocessor?), why don't you set up a special test lead with a unidirectional protection diode installed in the connector closest to the DUT? If the threshold voltage in the conduction direction is still too high, you may want to use a protection (zener) diode with a small signal schottky diode in parallel.

If you need something more versatile, set up two half-way powerful opamp followers, wired to two pots at their inputs and two clamping diodes at their outputs, connected to the signal - this, done properly and capacitively decoupled, will enable you to properly clamp any input signal asymmetrically in any desired way. It should also protect the DUT input from ESD to some degree.

P.S. I never felt the need to use such a contraption with any of my AWGs (DG811++, DG4000+, SDG6000+, HDG2000, MSO2000S). But I made it a habit to use a scope to look at the AWG output signal before I connect it to a sensitive input.

[mawyatt]

But I made it a habit to use a scope to look at the AWG output signal before I connect it to a sensitive input.

The wisdom of experience

If one is concerned about a power mains glitch/outage, then a UPS is in proper order!!

Edit: BTW the same goes for the Power Supply for sensitive circuits!!

Best,

[rf-loop]

But naturally my predictable rest of lifetime is not enough for test every possible setup combinations even once per setup. 

If you would choose  a 100mHz square, and a 99% duty, you are more likely to hit that high level right at the beginning of the rest of your life.

On that picture it looks like you hit that low level... 

That one magpie's nest type of signal connection that you recently brought up when you criticized the generator's frequency response. I will say one more and one last time. Most of the problems you'll encounter with oscilloscopes or generators are between them and the chair you sit. Next time I might say it less nicely.

Here is 100mHz and 99% Duty. And again hard PowOFF.
And yes, signal is 20Vpp and other is generator 10V DC out (also for trig)

If you set up values, that are far away from those that showed the issue, and want to compare, you also have a problem between the chair and the screen.

YOU ask'd this (if you remember)! And you get it.
And it still didn't show the problem you so desperately hoped for.

[eTobey]

But naturally my predictable rest of lifetime is not enough for test every possible setup combinations even once per setup. 

If you would choose  a 100mHz square, and a 99% duty, you are more likely to hit that high level right at the beginning of the rest of your life.

On that picture it looks like you hit that low level... 

That one magpie's nest type of signal connection that you recently brought up when you criticized the generator's frequency response. I will say one more and one last time. Most of the problems you'll encounter with oscilloscopes or generators are between them and the chair you sit. Next time I might say it less nicely.

Here is 100mHz and 99% Duty. And again hard PowOFF.
And yes, signal is 20Vpp and other is generator 10V DC out (also for trig)

If you set up values, that are far away from those that showed the issue, and want to compare, you also have a problem between the chair and the screen.

YOU ask'd this (if you remember)! And you get it.
And it still didn't show the problem you so desperately hoped for.

Of course it did not mean those values that i told you. 

I talked about spikes that went up to ~5V but you already set a level of 10V! 
Are you trying to hide the issue, or are you  trying to make me look bad?

[eTobey]

If you want to be sure that you won't overload your digital circuitry's input (Microprocessor?), why don't you set up a special test lead with a unidirectional protection diode installed in the connector closest to the DUT?

Yes i do want to make sure. Seems like i have to make such contraption, or spend a few figures more for a gen.

While trying and changing settings a lot, i do not really consider to get into a habit of checking the signal everytime. A contraption, that guards it well, no matter what, would be my choice.

Since the storing of the settings also does not work in all cases, i will not trust this device anyway.

[2N3055]

But naturally my predictable rest of lifetime is not enough for test every possible setup combinations even once per setup. 

If you would choose  a 100mHz square, and a 99% duty, you are more likely to hit that high level right at the beginning of the rest of your life.

On that picture it looks like you hit that low level... 

That one magpie's nest type of signal connection that you recently brought up when you criticized the generator's frequency response. I will say one more and one last time. Most of the problems you'll encounter with oscilloscopes or generators are between them and the chair you sit. Next time I might say it less nicely.

Here is 100mHz and 99% Duty. And again hard PowOFF.
And yes, signal is 20Vpp and other is generator 10V DC out (also for trig)

If you set up values, that are far away from those that showed the issue, and want to compare, you also have a problem between the chair and the screen.

YOU ask'd this (if you remember)! And you get it.
And it still didn't show the problem you so desperately hoped for.

Of course it did not mean those values that i told you. 

I talked about spikes that went up to ~5V but you already set a level of 10V! 
Are you trying to hide the issue, or are you  trying to make me look bad?

He already did..

https://www.eevblog.com/forum/testgear/siglent-sdg1032-as-bad-as-rigol-dg812/msg5505127/#msg5505127

[eTobey]

He already did..

https://www.eevblog.com/forum/testgear/siglent-sdg1032-as-bad-as-rigol-dg812/msg5505127/#msg5505127

Dude, thats the wrong level, and the wrong time on the signal, i tried to tell you, but it didnt work... 

[nctnico]

But naturally my predictable rest of lifetime is not enough for test every possible setup combinations even once per setup. 

If you would choose  a 100mHz square, and a 99% duty, you are more likely to hit that high level right at the beginning of the rest of your life.

On that picture it looks like you hit that low level... 

That one magpie's nest type of signal connection that you recently brought up when you criticized the generator's frequency response. I will say one more and one last time. Most of the problems you'll encounter with oscilloscopes or generators are between them and the chair you sit. Next time I might say it less nicely.

Here is 100mHz and 99% Duty. And again hard PowOFF.
And yes, signal is 20Vpp and other is generator 10V DC out (also for trig)

If you set up values, that are far away from those that showed the issue, and want to compare, you also have a problem between the chair and the screen.

YOU ask'd this (if you remember)! And you get it.
And it still didn't show the problem you so desperately hoped for.

Of course it did not mean those values that i told you. 

I talked about spikes that went up to ~5V but you already set a level of 10V! 
Are you trying to hide the issue, or are you  trying to make me look bad?

You make a good point here. When the generator is set to maximum output level, the output value is very unlikely to overshoot in the same way you and mortymore have shown. However, with a lower output level, the generator could overshoot when a mains interruption occurs. IOW: rf-loop should test with the same levels you and Mortymore have used. His screendump in the other thread does already show some negative undershoot.

[Njk]

Gentlemen, you're right, of course. It may not be strictly related to any real use case. End of discussion?

But I would like to say that the screenshots make me slightly concerned about the instrument's reliability because the voltages are dropping too soon. Perhaps I'm missing something, but with DG811, the process takes an order of magnitude time longer (see the image below). Similar signals, the yellow trace shows the DC waveform which is used to trigger the scope and the other trace is for the same 500 Hz square wave signal. There are almost 11 ms between the first sign of power problem in the left and the last falling edge in the right part of the screen. Both the channels are loaded with 50 Ohm pass-throug terminators. Nevertheless, the yellow line is horizontal, the voltage is not dropping. While on the screenshots above, despite the DC channel is not loaded, the voltage starts gradually decaying in less than 1 ms after the power off event. If enough energy remains inside?

It seems in DG811 the power failure signal is generated well in advance, likely using the information from the primary side of the PS (as it should be done). What if Rigol is more used to design an instrument-grade PSUs in-house (whatever it costs), while it's natural for Siglent to outsource that work to contractors? That also explains why the problem can be seen not with every instrument, as it depends on exact model of the general-purpose PSU, which may vary from batch to batch.

The timing may be directly related to the reliability because the device is controlled by application processor. Typically, a chip like that uses several power voltages and the power on and off sequences are not up to the user. The sequences are stipulated by the chip vendor and must be obeyed. To make it easier to use the chip, the vendor typically provides an auxiliary chip (PMIC) that performs the sequencing automatically. Anyway, for that processor, the sequence takes tens of milliseconds, IIRC.

So on power failure notification, the processor have to gracefully finish with all the business logic and with all the housekeeping tasks like bad block re-allocation, etc., then, optionally, to disable as much peripherals as possible, and finally to instruct the PMIC to start with the power off sequence. That requires reservation of enough energy for PMIC. Otherwise, all the power voltages will be abruptly interrupted, violating the prescribed sequence. The vendor does not qualify the processor for such abnormal cases. Nobody knows what will happen. Perhaps nothing, but it's actually a Russian roulette.