GMC chevrolet camaro 2000 Service Manual page 94

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General Information
Record/Playback
The displayed vibration information can be recorded
for later playback. The EV A retains stored data
for approximately 70 hours after the unit has been
unplugged from a power source. Data is recorded as
snapshots of vibration information. Each snapshot
consists of 10 different frames. Up to i O snapshots can
be recorded.
Press the RECORD button in order to record a
snapshot. The screen will display R? in order to
request a tag number between O and 9. These tag
numbers are the individual frames of the snapshot
recording. Then press ENTER to begin recording. New
data will replace the existing data when a number is
chosen that has already been used in order to
tag a snapshot.
Pressing the PLAYBACK button plays back the
recorded data. The screen shows P? in order to
request the tag number for the wanted snapshot. Once
the number is entered, the snapshot data displays
the letter P followed by the tag number then
press ENTER to play back the data. Then the screen
displays the letter F followed by a number between
O and 9 in order to indicate which frame of the
snapshot is being displayed.
Use the freeze function in order to freeze the display
at any point in the sequence during playback. You
can view individual frames in a forward or backward
sequence using the UP and DOWN arrow keys.
The display returns to the active screen when the
recording or playback of a snapshot is finished,
or when EXIT is pressed.
Averaging/Non-Averaging Modes
The EV A normally operates in an averaging mode that
averages multiple vibration samples over a period of
time. The averaging mode minimizes the effects
of a sudden vibration that is not related to the problem
(such as from potholes or from uneven road
surfaces). Most tests use the averaging mode.
The EV A is more sensitive to vibrations in the
non-averaging mode. The display is more
instantaneous and not averaged over a period of time.
The non-averaging mode is used when measuring
a vibration that exists for only a short period of time,
and during acceleration/deceleration tests.
Pressing the AVG button switches between the
averaging and non-averaging modes. During the
averaging mode, the screen will display AA. During
the instantaneous mode the top of the screen will
display IA
Vibration Diagnosis and Correction
0-83
Strobe Balancing
J
38792
95606
The J 38792 can strobe balance a rotating component.
A trigger wire is located on the top of the EVA,
which is used with an inductive pick-up strobe light
(timing light). The EV A triggers the strobe light at the
same frequency as the most predominant vibration.
The timing light clips on to the trigger wire. The
vibration sensor must be attached to input A. Input B
does not provide the strobe function.
Pressing the STROBE button starts the strobe
balancing function. The EV A will ask a series of
questions in order to determine the correct filter range:
low, medium or high.
The low, medium and high ranges prevent other
vibrations from interfering with the operation of the
strobe light. Press YES in order to select a range.
Press NO in order to go on to the next range.
The vibration/strobe frequency must fall within the
selected range.
The EVA will display the signal frequency; signal level
(amplitude), and filter range. The EVA is now ready
to begin the strobe balance procedure.