SDS1104X-E Issues(?) Auto Setup / Compensation / Noisy Trigger - Page 1
Forum section: electronics / testgear

author: vicenç
author_rank: Newbie
timestamp: May 29, 2018, 09:54:20 am
content: Dear electronic fans,Just bought a brand new SDS1104x-e scope for industrial communications debugging (485, CAN, etc). I was aware about the probe compensation issues of its little brother sds1202x-e had at some vertical division voltage for older firmware versions. It is widely reported.I was told by different commercial agents that the aforementioned issue was not present at sds1104x-e unit. Despite of this, when performing an overall test of our unit, i came across something that made me think about a similar defective HW-FW behaviour. By feeding the internally generated 3vpp square signal to CH1, with the probe switched to 1x and the CH1 setup also to 1x probe, if i press the autoset button the scope annoyingly fails to setup the vertical voltage division (it sets them to 5v) but also sets an unproper horizontal time division (too much time per division) resulting in a small rectangular yellow and slow rendering image). This is not happening when switching the probe at 10x and CH1 setup to 10x probe. Then the auto setup shows a perfectly centered square wave (voltage and time). I thought about the possible causes and concluded it could be due to some bad levels captured during the autosetting (when internal relays click to define the different input impedances).So I checked with probe switched to 1x and CH1 to 1x probe, ac coupled, and acwuired the square wave input at different volts per division. When i reached 100mv per division, therefore with a relatively significant zoom, when i "moved" across the vertical axis (with the offset button) i saw the uncompensated behaviour as depicted in the attached image. In fact the more i turned the offset downwards the more the effect was being displayed. I also attach a video for you.I also noticed that the signal/ADC seemed rather noisy at this levels. Just look at the noise being captured when setting the 5mv per division. In fact it also seems to have some triggering problems as seen in the video, despite it is a strong square signal. Been told by siglent that the compensation issue + noisy triggerin is rather usual at "large" zoom vertical levels for "cheap" scopes (despite in my previous rigol clone did not happen). Maybe theAuto Setupproblem is the most really annoying.I look forward to your commentsRegardsCompensation issue? https://drive.google.com/file/d/1rC0C8sWd-d35YUlEnw7e2dFY8eP33xQO/view?usp=drivesdkVideo noisy/triggering https://drive.google.com/file/d/1wAFel5XENpJIzgYxGytXb2TDDmfjvNAN/view?usp=drivesdk

author: Bob Sava
author_rank: Regular Contributor
timestamp: May 29, 2018, 02:13:20 pm
content: Distortion is normal according as per thishttps://www.eevblog.com/forum/testgear/is-this-the-siglent-compensation-issue-of-else/. What I don't understand is that, as you zoom further, eventually you get to end of the zoom range - why doesn't Siglent limit the range sooner if distortion is so bad?

author: vicenç
author_rank: Newbie
timestamp: May 29, 2018, 03:28:51 pm
content: Thank you Bob. I see the point about the compensation issue when overloading the adc input.However i am still annoyed by the problems with the Auto Setup with the probe at 1x. I might have the same origin but... could it be a defect in the firmware?Regards!

author: Bob Sava
author_rank: Regular Contributor
timestamp: May 29, 2018, 03:47:40 pm
content: While feeding calibration signal and pressing Auto Setup my scope is set to 500mV / 500us. If you does not, perhaps your scope is defective or you have tried to compensate the probe while zoomed in which is distorting square signal at normal gains.

author: tautech
author_rank: Super Contributor
timestamp: May 29, 2018, 04:23:12 pm
content: Quote from: vicenç on May 29, 2018, 09:54:20 amUser error. See vertical offset limit spec in datasheet.QuoteUser error.This effect is from trigger level hysteresis.See this post for further understanding:https://www.eevblog.com/forum/testgear/siglent-technical-support-join-in-eevblog/msg1261602/#msg1261602

author: vicenç
author_rank: Newbie
timestamp: May 29, 2018, 05:30:32 pm
content: Very impressed by knowledgeable people here! Thank you tautech and bob.I might have been too picky due to the issues with sds1205x-e, regarding the overliading and triggering hysteresis.But i do have the problem with the auto setup with probe set to 1x. So new sds1104x-e might be warned about this issue.Regards