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This tool uses an accelerometer to measure vibration frequency and amplitude levels. The top three amplitude levels with their corresponding frequencies are displayed on the EVA or EVA2's screen. This tool also has the ability to assist a technician in system balancing a propshaft system.
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When the EVA with the EVA2 memory cartridge, or the EVA2 is first powered up, the version number of the memory cartridge software is displayed and then the following screen is displayed.
The vibration sensor is a sensitive and fragile accelerometer. Take care to not drop or damage it.
The first photo shown below is the sensor all by it's self. The word "UP" is molded into the sensor. The sensor must be placed with the word "UP" facing up ONLY when strobe balancing a propshaft system. Standard vibration diagnosis does not require the word "UP" to be up.
The second photo shown below is the sensor attached to a magnetic base. The base comes in the EVA or EVA2 kit. The magnetic base allows quick attachment of the sensor to the seat frame, a solid point where good readings can be picked up by the sensor. The magnetic base also allows quick attachment of the sensor to many underbody points as well as engine points.
TIP: Think if the sensor as a "vibration sniffer"; the closer you get to the source of the vibration, the higher the amplitude level will be. If you don't get a good reading with the sensor on the seat frame, move it somewhere else.
RPM - Indicates that the vibration frequency unit of measurement is RPM rather than Hz. The advantage of using RPM rather than Hz is the ease of matching the RPM of the vibration to the RPM of a rotating component. For example: If the vibration frequency measured is 2000 RPM and the engine RPM is also 2000, there is an easy match to see. However, if Hz is used, a vibration frequency of 33.33 Hz is not an obvious match for the 2000 engine RPM. Pressing the RPM/Hz key will change the frequency units to Hertz (Hz).
A - Indicates that vibration sensor information is being received from input port A. There is also a port B. The additional port could be used if there was a second sensor.
Front View
Top View
AVG - Indicates that the EVA is in the averaging mode. Pressing the AVG button will turn off the averaging feature which makes it more sensitive; however, the averaging mode is best for steady, repetitive automotive vibration diagnosis.
G - Stands for G-Force, a numerical value for amplitude measurements. Typically there is not a specification for how low of a G-force reading is acceptable. This means that you must take before and after amplitude readings to verify that your repairs were worthwhile.
The top row is where the frequency with the highest amplitude level is displayed.
The second row is where the frequency with the second highest amplitude level is displayed.
The third row is where the frequency with the third highest amplitude level is displayed.
The EVA2 Keypad is identical to the EVA keypad except for the colors.
Yes - Answers questions with a positive response.
No - Answers questions with a negative response.
UP - Moves a selector symbol up on the screen.
Down- Moves a selector symbol down on the screen.
Strobe - Activates the strobe balancing feature of the EVA2.
0 - 9 keys - Used to enter data and also to select memory locations for the record feature.
RPM/Hz - Changes the vibration units of measurement from Hz to RPM and back.
Record - Starts the record feature. There are 10 memory locations to store data, keys 0 through 9.
Playback - Starts the playback feature. There are 10 memory locations to playback data from, keys 0 through 9.
A/B - Selects the A or B input port as the vibration sensor input port.
AVG - Turns on or off the averaging mode.
Enter - Moves the screen forward.
Exit - Backs up one screen.
Freeze - Freezes the display, pressing Freeze again activates the screen.
If a new sensor is purchased, it must be calibrated to work correctly. The following steps must be followed to calibrate the sensor:
Lay the sensor with the word "UP" side up on a flat, stationary surface. Make sure the cord does not try to tilt the sensor.
Plug the sensor cord into either input port A or B.
Power up the EVA.
From the main menu, as shown below, select "NORMAL MODE" with the Down Arrow key, then press the ENTER key.
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After the display initializes, about 4 seconds, select the sensor input port it is in by pressing the A/B key on the keypad.
The selected input will be identified on the first line of the display by its letter designation.
Press the number 1 key on the keypad to initialize the sensor calibration procedure. Do not move the tool or the sensor during this procedure.
Press the number 2 key three times to process the vibration sensor calibration. Follow any on-screen steps displayed.
The message "BURNING" will appear on the display. After a few seconds, a message requesting the sensor be turned over will appear on the display.
Turn the sensor over on the flat surface. Make sure the cord does not try to tilt the sensor.
Press any key to continue.
Calibration will be complete in about 20 -30 seconds when the live data screen appears as shown below.
Sensor Phase Shift Calibration.
The phase shift calibration procedure is performed at the factory and should not need to be performed again under normal use. However, any time the memory cartridge is changed, or anytime the EVA is suspected of having a problem, both calibration procedures shown in this section should be performed before calling technical assistance.
Plug the sensor cord into input port A. Do not move the sensor at any time during this procedure.
Lay the EVA on a flat surface.
Power up the EVA.
From the main menu, as shown below, select "NORMAL MODE" with the Down Arrow key, then press the ENTER key.
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Press the number 5 key on the keypad to initialize the sensor calibration procedure. Do not move the tool or the sensor during this procedure.
Press the number 2 key three times to process the phase shift calibration. Follow any on-screen steps displayed.
Do not press any keys until the screen instructs you to do so.
The screen will display the message "FREQUENCY", "PHASE ANGLE", "PEAK AMP", "CENTER FREQUENCY" with numbers incrementing next to them.
Wait 9 to 10 minutes until the calibration process is completed.
When the tool is finished, it will display the message "Burning Center Freq. Low = 39, High = 59.5, Med=49" (The frequencies listed are approximate, yours may vary).
Press any key to complete the calibration procedure.
The EVA will return to the live data screen shown below.
This page was last modified Thursday, March 05, 2009 09:02:37 PM
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