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    Scope buyers guide 'The Technical Perspective'



    This article aims to assist you in selecting a scope for diagnostic purposes by explaining how a digital scope works.







    Page 3/3


    Digital Dual channel scope (AVL DISCOPE 200)



    ..So why is this pattern not measured at the maximum speed setting?

    Each measurement point (dot) is a little bit of data that needs to be transferred from the Scope the the display of the PC or Lap top. At maximum sample rate is the scope outperforming (by far) the fastest computer. No this is not affecting the scope's accuracy as the scope's own buffer will store the 'overflow'. The overflow will be displayed as soon as the measurement is stopped.

    Recording buffer.

    The recording buffer when not used for overflow at a fast sampling rate, is used for a long recording time. This enables you to look at several seconds (or tens of minutes) of measurement data. With intermittent faults is this function VERY useful.

    The buffer length is a light grey scroll bar at the bottom of the screen. In the pattern below will the full picture (zoomed out) look like a lot of hash from many ignition / injection cycles.
    The zoomed in buffer (at the bottom of the screen) enables you to look at the pattern in detail...

    For the first step in Diagnostics you need to be able to Record ignition and injection, where does it all go wrong?

    Dual channel scope pattern in slow mode, but with large recording buffer. Channel 1 (top) is injection, channel 2 (bottom) is ignition.

    You will see what goes wrong, ignition or injection, it is as simple as that!



    In this case a crankshaft sensor wire worn through against the timing belt caused the fault.

    Check in the Help desk articles the #15 Toyota Soarer article to read the details of how the diagnostician found this fault.


    Conclusion

    Remember there is never one tool that will solve all you problems.
    It is a combination of :
    1. Knowledge (AECS training)
    2. Data (AVL and ATIS data systems)
    3. Equipment (AECS is distributor of AVL, VTEQ and GMTO diagnostic equipment)
    4. Technical support (read the AECS techtips to get an impression of our technical help)


    Happy Tool hunting !!


    Note 1: The ATS 801 and now the ATS 5000 can generate complex signals like the above crankshaft sensor signal to make the ECU think that the engine is running. With slide controls on the computer screen you can control the 'engine speed'. You are able to measure while generating with the scope function.      THIS IS RARE and very special !!!

    Note 2: The AVL DISCOPE 200 and ATS 801 and now the ATS 5000 are PC based, advantage: Email patterns for technical support and store patterns for maintenance records or reference. Alternative buy the reference patterns (ATIS) for your scope on CD rom.


    For AECS:

    H.P. Leijen (trainer / research)

    Web: www.aecs-nz.com

    E-Mail: hpleijen@aecs.net

    Ph: 06 8749 077




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