As first I wish to thanks Schurter for this product sample. My very own afterthought for requesting such a sample was for me to discover switch contacts resistance of a 100% healthy switch and also to perform a second inspection measurement, this be usable by a troubleshooter , so him to be able to make a judgment of this module health status.
Most usual thing and thought, this is people buying also a used DMM, while we all pay attention to inspect a used multimeter in the regard of measurements’ accuracy, exterior product condition, most ones never think that mains power switch condition this has great importance too.
An mains power switch with issues, this can be the cause so sparks at contacts area to appear, such a sparking event it can influence power supply stability, and a multimeter or Oscilloscope this introducing noise when it does measurements’.
From my experiences, a failing power switch this be in the input of a pulsing power supply, it will introduce noticeable noise at DCV rails these feeding an oscilloscope.
Review of known clean Test waveforms will become a challenge, because all waveforms on screen will now appear with noise.
Now the same failing power switch, if this feeding an classic transformer it would not demonstrate fast to notice side-effects, but eventually sparking will increase temperature and the danger of starting a fire.
But among possibilities there is and another one, some people discovered that while their benchtop multimeter was on soft-power mode (VFD was OFF), when them returned the next day, the meter was turned on.
If Mains voltage did not interrupted due power company issues, then the power switch it self, this started failing.
DMM4050, 4040, 8845A & 8846A all using analog DCV regulation among with switching power supply for the VFD Dot matrix display, now increased noise at the side of switching power supply, this it could possibly increase noise floor at mV measurements and or other issues.
Therefore and in conclusion, a good inspection of power switch condition this will save you the day. At specific Schurter power module, power switch this is permanently attached and soldered, in my review I could hardly find clean copper area so to place my Kelvin clips directly at power switch leads.
Even so I did manage to get a good repeatable measurement, and now I am aware that contacts resistance this is 0.5 milliohm.
My second mission was less difficult, I did select most easily accessible area for Kelvin clips installation, and now this new 3 milliohm measurement this is what every one can use as comparison point.
From today any troubleshooter and visitor of ITTSB blog, he may perform two measurements’ and discover health status of this power switch.
First test lead it should be placed over IEC plug pin, and the second test lead it should touch center pad of fuse holder.
Then just repeat this test with second active IEC plug pin and relative fuse holder pad.
Such an inspection it is now possible with out taking off DMM case, and by this way you may find the truth by not destroying calibration sticker at the bottom of the DMM.
I
TTSB Blog and me in person, I am original content creator, this translates that you are receivers of worthy information that you may use and make money.
Therefore feel free using donation links, and demonstrate you appreciation to my Blog with actions.
Regarding Schurter this is a very reliable products maker, but most retail customers can hardly find reasonably priced goods because all three web-shop distributors and their international sales partners, they acting very hostile regarding retail prices.
I did find KG10 this priced at 23 EUR for a single unit, and shipping pricing will add another 18 EUR at least, this makes a total of 41 EUR which I will describe as severe violation of anything called as reasonable price tag.