The purpose of this test is to examine and compare the primary current and voltage vs the secondary voltage within a DIS unit.
This test involves measuring a potentially hazardous voltage.
Please ensure you follow manufacturers' safety instructions and working practices and ensure the rated voltage for all accessories you are using meets or exceeds the expected voltage.
Uninsulated HT pickups are designed to clip around double-insulated HT leads only – they are not designed for direct connection to a hazardous live voltage.
To prevent injury or death, when connecting or disconnecting an HT pickup:
If the secondary voltage waveform appears inverted then this is because the output is positive-fired. Move the secondary ignition pick up onto a different HT lead.
Alternatively, you can change the settings to look at a positive-fired coil by selecting the settings for channel B and changing the probe from Secondary Ignition Probe (Inverted) to Secondary Ignition Probe (Pos).
The orientation of the current clamp relative to the wire will determine whether it has a positive or negative output. If a live waveform does not appear on your screen, or appears to be inverted, try reversing the orientation of the clamp.
This helpfile refers to a 10:1 attenuator. If you are using a 20:1 attenuator please adjust the Probe settings for the relevant channel. These settings can be found under the Channel Options button, then: Probe > 20:1 Attenuator.
These known good waveforms have the following characteristics:
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