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How not to Damage an Oscilloscope

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  • Tarot Superstars
    • Aug 2023
    • 60
    • United Kingdom

    How not to Damage an Oscilloscope

    I have jut got my first analogue oscilloscope. An Isotech 620 20MHz.

    I want to learn how not to damage it, and I found instructions on the internet obscure.
    They talk about ground, earth, floating ground, this, that....
    But they don't actually say anything anything useful so far.

    I want to know:
    Don't connect exactly this to exactly there or it blows up.

    For example, I am tracing a signal from a function generator in an audio amp, or testing for voltages in different parts of a circuit.
    I want to know what not to connect it to. The instructions on the internet have no precise instructions and they were too general.

    I have read things on the difference between negative, ground, and so on, and I still don't understand it.

    Could someone just spell it out for me.
    How not to blow up the oscilloscope.

    I figured, just measure the voltage with a multimeter and check the maximum voltage and current rating for the oscilloscope before using the oscilloscope, but then the internet says something about ground that makes this idea seem useless.

    Background on me:
    I completed a short video course (~25h) on electronic repair. I have a physics BSc. I have dabbled in electronics since I can't remember, I have read a few electronics and radio books, but never took a proper certified course. I wouldn't say that I understand even 1/20th as much that a good electronic engineer does.
    Last edited by Tarot Superstars; 08-29-2023, 02:41 PM.
  • stj
    Great Sage 齊天大聖
    • Dec 2009
    • 29511
    • some shithole run by Israeli agents

    Re: How not to Damage an Oscilloscope

    dont connect the scope probe ground clip to anything other than ground on what you test.
    thats the main thing - be carfull with psu's that the output ground really is ground.

    someone can post a like to the eevblog video i hope

    and always keep your probe(s) set to x10


    • harp
      Badcaps Veteran
      • Jun 2022
      • 260
      • Planet Earth

      Re: How not to Damage an Oscilloscope

      There is eevblog video about this
      but I am very sure that you see it already

      Yes, the problem is with ground, and to help save your equpment in lab is using some isolation transformer 1:1 ratio. But, if you measure two chanel simultaneously, the ground must be the same, not different potencial.
      Be avare of hot and cold ground also, it is different.

      Before you put ground clip on whatsoever, you may measure voltage between to be sure that is the same potential.

      Also, if you living from repair, it is also handy to have battery scope near by.
      Last edited by harp; 08-30-2023, 03:13 PM.


      • Tarot Superstars
        • Aug 2023
        • 60
        • United Kingdom

        Re: How not to Damage an Oscilloscope



        • CapLeaker
          Leaking Member
          • Dec 2014
          • 6359
          • Canada

          Re: How not to Damage an Oscilloscope

          Or a differential probe.