GMC Chevrolet Camaro 1998 Service Manual page 108

0-.96 Vibration Diagnosis and Correction
EVA Sensor Placement
Proper EVA sensor placement is critical in order to
take proper vibration readings. The sensor can
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be placed anywhere on the vehicle where vibrations
are felt. Use putty or a hook and loop fastener in order
to hold the sensor in place on non-ferrous surfaces,
such as the surface of the steering column.
A magnet is supplied in order to hold the sensor to
ferrous surfaces.
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Vibrations are typically felt in an up-and-down
direction. The sensor is directionally sensitive.
Therefore, place the sensor as flat as possible with
the side marked UP facing upward. Place the UP side
of the sensor in the exact position every time for
consistent results when repeating the tests or making
a comparison.
General Information
EVA Display
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The EVA offers the following main display features, all
of which are described below:
• Freeze
• Record/Playback
• Averaging/Non-averaging modes
• Strobe Balancing
Freeze
Pressing the FREEZE button on the keypad activates
the freeze function, which locks the display of data.
The display shows FRZ at the top. The freeze function
is useful when conducting an acceleration/deceleration
test in which the significant amount of vibration
registers only for a very short time. Pressing EXIT or
the FREEZE button again deactivates the freeze
function.
Record/Playback
The displayed vibration information can be recorded
for later playback. The EV A retains stored data
for about 70 hours after the unit has been unplugged
from a power source. Data is recorded as
SNAPSHOTS of vibration information. Each snapshot
consists of
1
O different frames. Up to 1 O of these
snapshots can be recorded.
Press RECORD 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. New data
will replace the existing data when a number is
chosen that has already been used in order to tag a
snapshot.
Pressing PLAYBACK 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 is displayed: P and the
tag number will appear. Then, an F and a 0-9 will be
displayed in order to indicate which frame of the
snapshot is being displayed.
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