Oscilloscope Questions

Discussion in 'General Electronics Chat' started by Netguru5, Dec 14, 2009.

  1. Netguru5

    Thread Starter New Member

    Oct 28, 2009
    4
    0
    Hi,

    I finally got ahold of a fairly nice scope and had some newbie questions. I've read quite a bit of info on this scope and others on its use, but not much in practical tests on complex systems like motherboards. Can I damage the scope by poking around with the probe? And where should I connect to ground when checking components on a motherboard like IC's or crystals? how would I check if a cap was blown? I was able to check the frequency of a crystal without the ground clip attached, but what grounding point should I use on the motherboard? Im learning so any advice would be appreciated.

    Thanks!
     
  2. ELECTRONERD

    Senior Member

    May 26, 2009
    1,146
    16
    An obvious, yet clearly important concept, is to note whether your measuring AC or DC on the scope. From there, if your unsure as to what voltage your measuring, you should usually work your way down from the highest voltage setting.

    Have you read the manual for your scope? What model is it?

    Austin
     
  3. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
    2,040
    287
    If you have a 10:1 probe, you're unlikely to do any damage to your scope with any modern equipment, no matter what you do (unlike the nasty high-voltage R.F. stuff I work on!)

    You have far more danger of torching the ICs and such by shorting out pins with your scope probe.

    The best way to test out any scope however, is with the scope calibrator on the front panel. These are usually pretty easy to identify...it may look like a little loop of wire, or perhaps a towel bar for a hamster. There will be a calibrated 1KHz square wave on this...sort of a universal test generator for scopes. :)

    eric
     
  4. VoodooMojo

    Active Member

    Nov 28, 2009
    503
    53
    Google search for datasheets for discrete and integrated components. Register at data dumps such as IC Masters etc. Get to know as much about a component and or circuit by researching first, probing second. You will learn where to find grounds, Vss, Vcc, triggers, outputs, resets, clocks, ......
    Become one with the electron. Explore the inner world of electron manipulation and many fantastic wonders shall be revealed!
    Then, when you know what a component is supposed to be contributing to a circuit, the volt meters, oscilloscopes, frequency counters, ohmmeters, ampmeters, grid dip oscillators, spectrum analyzers, et al, will be self evident as to their application.
    More over, build as many circuits as you can. Bill Marsden and others have a treasure trove of info and circuits for you here. Understand thouroughly all the circuits you build. Use meters and scopes on good, performing circuits. Bug the circuits and troubleshoot again with scopes and meters to gain experience.
    Learn what it takes to generate sine, square, sawtooth, etc wave forms and know what each are used for.
    Then the scope is really a tool, not just a toy to produce pretty little waves.
     
  5. boriz

    New Member

    Jul 16, 2009
    48
    0
    Usually you’ll see the voltage limit printed on the front panel of the scope beside the probe input socket. One of my scopes says ‘300v peak’, another says ‘400v peak’. If you are sure there is no voltage in the circuit under test that can exceed this limit, then you should not worry. If there is some doubt, switch the probe to 10x (attenuator). This essentially divides the tip voltage by ten for the scope input, so you can for example measure up to 3000v for a 300v peak limited input.

    NOTE 1:
    Some inductive components can produce spikes over 300v. Look out for that.

    NOTE2:
    Don’t switch the probe between 1x and 10x while it’s connected to a voltage. The switch is a make-before-break type and it will cause a brief short, possibly damaging the probe or the circuit. Been there, done that.

    NOTE3:
    Enjoy. Scopes are cool :)
     
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