Benelli TnT1130, Workshop Manual

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376
MF13
Specially, accurate measurements will not be possible if you
want to measure the injection time (Fig. 1). Simply change the
time division value, lowering to 1 ms for each division (Fig.2).
In ths case the signal will now show the entire form and appear
clearly and easily quantifiable.
Therefore, when selecting the voltage and the time measurement
scales, it is advisable to adopt the resolution that provides the
best view of the signal to be measured. This will also allow the
best positionning of the measurement cursors.
10.3.6.8 AC/DC READING SELECTION
The two windows with the letters AC and DC may be used for
enabling two different measurement modes.
Select DC to view the direct component of the signal.
The direct component will be cancelled and replaced with the
alternative component if AC is selected.
This option is extremely useful to highlight the disturbance
overlaying a direct signal.
A typical example is testing the voltage of a battery. If the test is
executed in AC, hte reading shows the residual signal generated
by the rectifier diodes of the alternator.
The measurement with the oscilloscope in AC mode (alternate)
allows the selection of small voltage resolution (e.g.1 V/dv), while
detecting and displaying a high voltage direct signal.
In the above example (battery check), the positive voltage of 12
- 14.7 V is tested and controlled with a test sensitivity of 1 V7/
division. The resulting oscillogram will show a signal on the zero
line with a set of arcades in the positive quadrant (Fig.1). Such
arcades confirms that the alternator and the charging system
are in working order.
DETECTION AC
0.5 Volt/div
DETECTION DC
0.5 Volt/div
v
T
DC
AC
MAN
EXT
Va:-10.0mV
Vb:-10.0mV
Dv:0.0
Dt:5mS
A
B
INT
8
6
4
CH1
SYNC.
TYPE
OPTIONS