Tecnotest SL31205 Manual Operativo página 59

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______________________________________________________________________ OSCILLOSCOPE KIT
Then, if the spark plug voltage is positive, select COIL POSITIVE SECONDARY.
If this is not the case, if the spark plug voltage is negative, select COIL NEGATIVE
SECONDARY.
The display shows the correct secondary signal.
Set a trigger level as high as possible to avoid synchronization on the exhaust spark.
In a static ignition engine, alternation between sparks in explosion phase and sparks in
exhaust phase occurs. Explosion phase sparks have a higher voltage peak and a shorter
spark time than exhaust phase sparks.
If a trigger level of 2-3 KV is set, the oscilloscope displays the explosion and exhaust
sparks in a confused manner.
The figure shows how a static ignition engine at about 2000 rpm with a synchronism
level of about 2 KV. The explosion and exhaust sparks are displayed correctly if the
operation is stopped by means of F4. If this is not the case, if the operation is not
stopped by means of F4, explosion and exhaust sparks alternate confusedly on the
screen.
OPERATING INSTRUCTIONS 55