• Topic ID: id_18718299
  • Version: 1.0
  • Date: Sep 20, 2018 2:06:21 PM

Elevation Encoder Assembly Replacement

Prerequisites

Overview

Procedure Effectivity:

Procedure

  1. Raise the table to maximum height.
  2. Remove right Gantry Side Cover.
    • warning
    • POTENTIAL FOR SHOCK.
    • VOLTAGE MAY BE PRESENT.
    • USE PROPER LOCKOUT/TAGOUT PROCEDURES BEFORE REPLACING COMPONENTS.
    Notice Image
    • notice
    • Always turn OFF the HVDC before the 120 VAC. Turning OFF 120 VAC power before HVDC power can result in equipment damage.
  3. Remove power from table by turning off 120VAC, Axial Drive and HVDC switches on Service Switch Panel.
  4. Remove the Table Base Covers and the left Side Panels.
  5. Remove Tie-Wraps from the cable on the Encoder and disconnect the cable.
    note:

    Pay attention to the locations of the four Cam Switch connections on the Encoder Assembly, before removing them. Restore the wires to their original configuration on the replacement Encoder Assembly.

  6. Remove four Cam Switch connections from Encoder Assembly.
  7. Remove the two bolts that fasten the Elevation Encoder Assembly to the table base.
  8. Slide the Assembly towards the large sprocket, to relieve belt tension.
  9. Remove the belt from the Encoder Assembly.
  10. Remove the defective Encoder Assembly from the table.
  11. On the new Encoder Assembly, verify that the flexible coupling is tight, then loosen the pinch set screw for the aluminum cam.
  12. Install the replacement Elevation Encoder Assembly:
    1. Replace the belt, making sure that the Master Link is at the dimple on the large sprocket.
    2. Slide the Elevation Encoder Assembly away from the large sprocket, until the belt deflects 0.250" with 32 - 35 oz. Applied at its mid-span.
    3. Tighten both screws, to fasten the encoder assembly in place, with tension on the belt.
    4. Verify that the tension on the belt is correct.
  13. Connect the Cam Switch connections and the Encoder cabling.
  14. Adjust the cam positioning.
    1. Ensure that both rollers on the aluminum cam are engaged at maximum table height.
    2. The first cam (on the outside of the table) should slacken when the table is at 699.09 I 0.25 mm.
    3. Tighten the set screw when the cam is properly positioned.
  15. Use Tie-Wraps to secure any loose cabling from the Encoder Assembly.

Finalization

  1. Follow the procedure on Table Characterization to Characterize the Table Elevation.
  2. Using the service switches on the MTCB, move the Table up and down, and the Cradle in and out.
  3. Use the gantry control keys to move the Table up and down, and the Cradle in and out.
  4. When the Table functions properly, reinstall the Table Base Covers, the Side Panels and the Gantry Side Cover.