Author Topic: Avoid killing an SHS806 DSO  (Read 1247 times)

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Offline mcinque

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Avoid killing an SHS806 DSO
« on: June 07, 2018, 07:47:04 pm »
I recently put my hands on a Siglent SHS806. It has a minor bug that Siglent is refusing to correct but I will explain this in a separate post.

Now, since in this model the grounds are shared between the two channels (they are not isolated as the SHS1000 series), the only precaution to not kill this model seems to be keep both ground clips at the same potential (and don't apply higher voltages than the specs on the inputs). Please, correct me if I'm wrong.

But a doubt came in to my mind after I read on the manual at page 5: "Do not connect the ground spring to voltages higher than 42 V peak or 30Vrms from earth ground."

Well, AFAIK, if the scope is running on battery it is isolated from ground, so it shouldn't matter where the ground clip is connected, as long you keep the two grounds at the same potential.

In your opinion, what they mean with that warning?

Maybe they are warning that when the scope is running when it is grounded via usb to earth ground?
 

Offline capt bullshot

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Re: Avoid killing an SHS806 DSO
« Reply #1 on: June 07, 2018, 08:26:19 pm »
This is the usual personal safety warning, because the ground is connected to exposed parts that you could touch by accident. Voltages below these values are considered safe to touch.
Safety devices hinder evolution
 
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Online tautech

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Re: Avoid killing an SHS806 DSO
« Reply #2 on: June 08, 2018, 05:23:38 am »
Like floating an ordinary scope mcinque you need be aware any metallic fixtures take on the potential of the reference lead. That's all this warning is about......your safety.

WRT this bug you mention, has it not been fixed in the latest firmware just out yesterday ?
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Offline mcinque

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Re: Avoid killing an SHS806 DSO
« Reply #3 on: June 08, 2018, 08:45:57 pm »
Thanks for the advices, I was more concerned for the safety of the instrument  ^-^

In fact, I understand well that if a ground clip is connected to live, also the other ground clip will be connected to live (exactly as you stated with floating a bench oscilloscope and connecting its ground to live: all the chassis would become live). Since in this models there is no exposed metal part, if you leave it floating as it should be (without usb cable connected for example) it should be safe, do you agree?

Quote
WRT this bug you mention, has it not been fixed in the latest firmware just out yesterday ?

It's a bug affecting the zooming in normal trigger mode. It's been discovered in january 2017, posted on Youtube and reported to Siglent.




I reported this bug some months ago and they told me that they reproduced the issue but "since they're developing a new shs800 series, they are working on a revamped firmware and they doesn't release any patch for this issue until the new shs800 is ready". Basically it seems to me that they don't care too much of their "old" customers, this is something known at least since january 2017.

How to reproduce the issue
set the SHS806 to scope mode
set the trigger mode to NORMAL
apply the signal to the input and scale the V/div accordingly
the waveform shows on the screen correctly
now remove the signal
the signal remain on the screen as expected in normal mode
try now to zoom on the waveform by changing the time/div to faster values

what should happen

the waveform is scaled accordingly to the time/div setting

what happens instead
it's impossible to scale up to 5nS

I can workaround the issue by stopping the capture, but a patch will be better.

On https://www.siglent.eu/Downloads I see the release date is still 2015. Should I look for other sources?
 

Online tautech

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Re: Avoid killing an SHS806 DSO
« Reply #4 on: June 08, 2018, 09:32:59 pm »
On https://www.siglent.eu/Downloads I see the release date is still 2015. Should I look for other sources?
Here's the link for the latest FW for 60,100 and 150 MHz models.
https://www.siglenteu.com/download/6166/

Be sure to carefully read the firmware install instructions as there's a cfg file that needs be installed too.

Here's the changelog:
1. The probe attenuation factor is considered in the trend diagram mode.
2. Digital filtering state remains even in scope stop state.
3. The switchboard can record the configuration of the math waveform.
4. The Math waveform takes into account the probe coefficient configuration.
5. Improved Win10/EasyScope connectivity.
6. Improved vertical cursor measurements when changing scales on fixed/stopped waveforms
7. Enabled self-calibration under Normal or Single mode.
8. Improved edge trigger performance for single and normal mode
9. Increased Single trigger data depth in long storage mode(from 20kto2Mpts).
10. Increased stability of trend map transfer of CSV data to USB memory devices > 4 GB
11. Optimize the display algorithm of multi-meter trend chart and oscilloscope trend chart. Solves the slow response of keys after long recording time.
12. Enhanced FFT data usage. Long storage features 40 times the corresponding frequency points used in ordinary storage.
13. Improved read/write timeout to the U disk.
14. Time stamp information added to the saved CSV file.

Quote
Thanks for the advices, I was more concerned for the safety of the instrument  ^-^

In fact, I understand well that if a ground clip is connected to live, also the other ground clip will be connected to live (exactly as you stated with floating a bench oscilloscope and connecting its ground to live: all the chassis would become live). Since in this models there is no exposed metal part, if you leave it floating as it should be (without usb cable connected for example) it should be safe, do you agree?
Yes, agreed but there are other potential sources of connection to the live chassis. Probe Cal and USB.
Just be careful and properly think risk through.  ;)

I don't have an SHS model now so I can't check these issues but rather just link them through to Siglent for them to properly investigate.

« Last Edit: June 09, 2018, 01:22:11 am by tautech »
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Offline pantelei4

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Re: Avoid killing an SHS806 DSO
« Reply #5 on: June 09, 2018, 12:33:07 pm »
It's a bug affecting the zooming in normal trigger mode. It's been discovered in january 2017, posted on Youtube and reported to Siglent.
Hi. This is my video.
The new firmware completely corrects these bugs.
I'm satisfied with the work of the oscilloscope after updating the firmware.
 
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Offline pantelei4

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Re: Avoid killing an SHS806 DSO
« Reply #6 on: June 09, 2018, 12:58:58 pm »
Since in this models there is no exposed metal part, if you leave it floating as it should be (without usb cable connected for example) it should be safe, do you agree?
Yes, I use it with a hot floating connection up to 2kV.
 

Offline mcinque

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Re: Avoid killing an SHS806 DSO
« Reply #7 on: June 09, 2018, 04:32:35 pm »
Here's the link for the latest FW for 60,100 and 150 MHz models.

Wow, is fascinating how "official" Siglent support has "forgot" to report me that news and you did promptly :) Thank you!
It is fixed now. However, in my opinion they took too much time to release the new firmware.
« Last Edit: June 09, 2018, 04:36:55 pm by mcinque »
 


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