• Topic ID: id_15460365
  • Version: 5.0
  • Date: Mar 6, 2020 9:57:24 PM

Gantry Balance Hardware Check

Prerequisites

Overview

This procedure will identify the checks available to verify operation of the Gantry balance hardware.

1 Test points and LEDs

Procedure

  1. Verify power on the Balance Sensor Buffer board using the information in Table 4.

2 Sensor Test

The sensors are Piezoelectric devices that send a signal to the Balance Sensor Buffer board proportional to the amplitude of the vibration sensed.

Procedure

  1. Make sure the sensor boards are torqued to 20.4 in-lbs (2.3 N-m) to the gantry base. A loose sensor board will give bad results.
  2. Connect a voltmeter between TP3 or TP4 (Sensor 1 or 2) reference to TP5 ground on the Balance Sensor Buffer Bd. With the cover off the sensor under test, blow or “lightly” tap on the sensor. You will see a variation in voltage signal amplitude coincident with the tap or air flow across the sensor in the range of 0mV to a few hundred millivolts offset from ambient.
  3. If the prior step did not produce any change in readings, the sensors can be isolated and tested in the same way by disconnecting the sensor from the buffer board and connecting the voltmeter to the 2 wires from the sensor under test. There is no bias voltage required by the sensors.

3 Software Files

Below is a file that can be used to see if the sensor data if being seen by the software. See Gantry Service Balance Theory for descriptions of other software files used by the gantry balance software.

Procedure

  1. Open a C-shell and type the following:


    cd /usr/g/fw
    more axveldata.txt
                    

    You will see the following information contained in the file. The format of the file is semicolon separated data. The first item is the number of the data line. Field 4 contains sensor 1 data (on the front face of the gantry frame) and field 5 contains sensor 2 data (inside face of gantry frame). The file contains 2047 lines with the first 1023 lines containing actual data from sensor 1 and has sensor 2 actual data starting on line 1024. The sensor 1 data in line 0 shown below is 33552 with sensor 2 data as 0. Further down in line 1024, sensor 1 is now seen as zero and sensor 2 data now 33504. Generally speaking data in the vicinity of 30,000 is normal data. Expect a significant change such as zero or orders of magnitude change to indicate a problem with the data.


                      
    0;938525;2925;33552;0;504;9;8;30
    1;943828;3105;33382;0;503;9;8;30
    2;949140;3284;32954;0;502;9;8;30
    3;954450;3464;33326;0;502;9;8;30
    4;959760;43;33216;0;501;9;8;30

    1021;6375023;3101;33475;0;499;60;8;30
    1022;6380352;3281;33190;0;500;60;8;30
    1023;6385676;3461;32978;0;499;60;8;30
    1024;6390997;41;0;33504;499;60;8;30
    1025;6396324;221;0;33761;500;60;8;30
    1026;6401648;401;0;34085;500;60;8;3
                    

4 Finalization

No finalization steps.