Siglent SDM3055 2 wire resistance mode became unresponsive - Page 1
Forum section: electronics / testgear

author: szszoke
author_rank: Regular Contributor
timestamp: April 24, 2021, 10:53:21 pm
content: Hello!I noticed a weird phenomenon on my brand new Siglent SDM3055 in the 2 wire resistance mode.Somehow it managed to become unresponsive and it did not react to anything connected to the output.I was making some custom banana cables and I was testing them via the 2 wire resistance mode.The meter was left sitting running with either a custom banana cable shorting the inputs or with nothing connected.Eventually I plugged in a cable and the meter didn't react, it kept displaying overland.I thought that I somehow made a bad solder joint so I tested with a known good cable only to see the meter display overload.I switched to DC volts mode and then back, with no change in the behavior.I rebooted the device and the resistance mode started working again.The only unusual thing that happened was that the banana plugs were lukewarm, I could hold them in my hands without any discomfort, so the resistance measurement was affected by what I think was thermoelectric effect. I think this couldn't have caused the issue that I experienced.If the warmer plug was plugged into the positive input, the resistance measurement was negative, if the warmer plug was plugged in to the negative input, the resistance reading was higher and it kept going down until it settled at 0.015 Ohms.I'm wondering if someone else encountered this issue.I'm running FW 1.01.01.22R1 and the HW ID is 03-00-00-13-00.I feel that the resistance mode is a bit wonky on this meter.If I just hold the positive lead for example, without touching any conductive part, the meter starts oscillating between overload and some hundreds of megaohms.If I hold the conductive part of the positive (and nothing else) the meter shows about 30 megaohms.

author: szszoke
author_rank: Regular Contributor
timestamp: April 24, 2021, 11:08:14 pm
content: Actually, i just noticed something weird. If I a cable is plugged in to the positive input, and that cable bumps into the surface of my table, the DC voltage reading jumps up to over 100mV.These are the included silicone leads, but my custom silicone cables are also causing the same behavior.I tried the same thing with a PVC banana cable and those are not causing the voltage reading to change when they bump into the surface of my table.I can make a quick video if what I wrote doesn't make sense.

author: tautech
author_rank: Super Contributor
timestamp: April 24, 2021, 11:08:38 pm
content: For accurate measurements you need to Rel (null) the lead resistance and/or change the measurement speed.P31https://int.siglent.com/upload_file/user/SDM3055/SDM3055_UserManual_UM06035-E02A.pdf

author: szszoke
author_rank: Regular Contributor
timestamp: April 24, 2021, 11:29:39 pm
content: Here is a video of the phenomenon with the probes:https://youtube.com/shorts/D9ZFvJ1OgKQI tried wobbling the cable in the air making sure that it didn't touch the table and I did not encointer the phenomenon.

author: szszoke
author_rank: Regular Contributor
timestamp: April 24, 2021, 11:35:25 pm
content: Quote from: tautech on April 24, 2021, 11:08:38 pmThanks for the suggestion but I think you should watch the video from my previous comment.I don't think my explanation came through. This doesn't seem like an offset voltage that I can null out.It looks as if the cable is exhibiting some sort of piezoelectric effect, if that even makes any sense.

author: szszoke
author_rank: Regular Contributor
timestamp: April 24, 2021, 11:51:17 pm
content: Either way, I'm not sure if this phenomenon with the probes is related to my original issue, which is the resistance mode becoming unresponsive and showing overload even if the inputs are shorted together.Unfortunately I cannot reproduce the behavior reliably.

author: tautech
author_rank: Super Contributor
timestamp: April 24, 2021, 11:59:41 pm
content: Quote from: szszoke on April 24, 2021, 11:35:25 pmYes well what else would you expect when waving an antenna around.

author: szszoke
author_rank: Regular Contributor
timestamp: April 25, 2021, 12:08:01 am
content: Funny thing is, I have to actually hit the table with the cable. If I just wave it around in the air then nothing happens.It seems that whatever is happening it is caused by the mechanical impact of the cable hitting the table.