RIGOL MSO1074Z-S, 14 months after purchase - Page 1
Forum section: electronics / testgear

author: prasimix
author_rank: Unknown
timestamp: January 12, 2016, 04:28:55 pm
content: I'd like to hear your opinion since according to the support answer form the RIGOL authorized dealer this topic is closed. I bought a new MS01074Z-S about 14 months ago. During this time it was used frequently and it wasn't abused in any sense (e.g. overvoltage on inputs, no AC mains surges, mechanical pressure on probes and input BNC connectors, etc.). Recently I noticed that something is wrong when no signal is present on any of its 4 inputs. At first I thought that probes are picking up some external noise, but even without probes and when I selected input grounding the situation was not improved a bit. Here is the screenshot with all inputsgroundedbefore I contact their dealer technical support:Technical support suggest me self-calibration. I follow that and self-calibration begins. After lots of clicking and traces moving around the calibration is successfully finished. After restart I got the following (again all input are grounded):It seems like an improvement but just selecting the AC coupling even without probe cable connected I got the following on the Ch3 that looks better then others on the above picture:I sent the same screenshot to the dealer and I got the following response:QuoteWith different time base grounded ch3 looks like this:My question is does anybody experienced the same behavior on not completely new MSO or any other RIGOL's device from the same series/class? Thanks in advance.

author: Howardlong
author_rank: Super Contributor
timestamp: January 12, 2016, 11:31:46 pm
content: Looks pretty much identical to mine in the scenarios given.You are operating at 10mV/div on 10X, you're seeing the ADC noise on the LSBs.

author: prasimix
author_rank: Unknown
timestamp: January 13, 2016, 09:17:36 am
content: Quote from: Howardlong on January 12, 2016, 11:31:46 pmThanks, I noticed that today. For some reason I was convinced that it was much better some times ago. Unfortunately I have no screenshots from that time and obviously self-calibration is all what could be done to improve "reference" state. Next time (if it comes) I'll go fishing for some bigger name.

author: prasimix
author_rank: Unknown
timestamp: January 13, 2016, 09:57:20 am
content: Anyway, as an reference for future buyers, here is what I got this morning (again without any other equipment in closed proximity switched on):Another day, another luck? After self-calibration the situation was improved. Here is how it looks without probe plugged in and AC coupled:... or grounded:So it seems that the new practice would be to starts a day with self-calibration.

author: mcinque
author_rank: Unknown
timestamp: January 13, 2016, 12:49:23 pm
content: Are you sure that you didn't move ANYTHING in your lab? I experencied much noise from switching lamps and wall power adapters; that noise change even moving a hand or a metal can in the surrounding.

author: Performa01
author_rank: Super Contributor
timestamp: January 13, 2016, 03:23:15 pm
content: Your probes probably act as antenna and catch all kinds of interference from the environment.Your test only makes sense with probes disconnected at least. Even better yet, connect a 50 ohm terminator to the scope input instead. Only then you'll get a consistent picture regarding analog frontend noise.

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: January 13, 2016, 06:43:59 pm
content: I've got a desk lamp on my bench that even with it powered off when I move my hand near it I can see changes on my oscilloscope. Same thing with the ceiling light/fan 5-6 feet away from the scope (though on the same circuit), hanging in the middle of the room.

author: MrSlack
author_rank: Frequent Contributor
timestamp: January 13, 2016, 06:48:18 pm
content: That's pretty bad. The noise on my Tek 465B's on 5mV/div isn't visible at all on a shorted 1m long probe. Dead sharp trace.That is with two crappy Ikea LED lamps about 20cm away, in the approach window of London Heathrow and about 50 WiFi SSIDs visible

author: TheSteve
author_rank: Unknown
timestamp: January 13, 2016, 07:02:08 pm
content: Quote from: MrSlack on January 13, 2016, 06:48:18 pmTime for you to check out Dave's video on the subject:http://www.eevblog.com/2014/04/10/eevblog-601-why-digital-oscilloscopes-appear-noisy/

author: ebastler
author_rank: Super Contributor
timestamp: January 13, 2016, 07:05:56 pm
content: Quote from: MrSlack on January 13, 2016, 06:48:18 pmWell, the posts above show the signal at 1mV/div. And I'm not sure whether the poster had shorted either the probe or the scope input; I think this was mostly measured with open input jacks?As mentioned before in this thread, measuring with a 50 Ohm termination right at the input is recommended if you want to make sure that there is no environmental noise coming in, and want to assess purely the noise of the scope's input stage.

author: MrSlack
author_rank: Frequent Contributor
timestamp: January 13, 2016, 07:37:32 pm
content: TheSteve: Aware of that.ebastler: Gotcha - didn't see the 1mV one. Not terrible then.Agreed.

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: January 14, 2016, 12:36:52 am
content: I was referring to probe plugged into scope with probe end not connected to anything (full on antenna mode). I was just mentioning because its not necessary for other electrical equipment to be turned on for it to be emitting noise that can be picked up.

author: smgvbest
author_rank: Unknown
timestamp: January 14, 2016, 03:35:51 am
content: Quote from: MrSlack on January 13, 2016, 06:48:18 pmDave did a video about why you would not see this on a analog scope. the 465B is a analog scope so not seeing on that scope is not a surprise.

author: tautech
author_rank: Super Contributor
timestamp: January 14, 2016, 07:18:16 am
content: https://www.eevblog.com/forum/testgear/siglent-sds1000x-series-oscilloscopes/msg825532/#msg825532

author: Fungus
author_rank: Super Contributor
timestamp: January 14, 2016, 07:28:29 am
content: Quote from: prasimix on January 13, 2016, 09:17:36 amHave you got any new lamps in that time? A new PC?Rigol are correct though. 0.5mV of noise isn't anything to worry about (on a budget scope).

author: prasimix
author_rank: Unknown
timestamp: January 16, 2016, 02:58:15 pm
content: Thanks everyone for your inputs. Dave's video helps a lot. So far I can concluded that scope is working as expected. Only that remains to some extent strange is how self-calibration each time "improve" something.

author: ice595
author_rank: Regular Contributor
timestamp: January 16, 2016, 07:57:17 pm
content: Same thing with my DS1054Z, it seems like its picking up some periodic noise signal on all 4 channels when it on the 1mv/div range (some channels are worst than the other).would be interesting to see where the noise is coming from