3. Remove the PCB cover and set aside. 106 54-0147 Replacing the Main PCB Replacing the Main PCB . With a PC connected to the ADCU’s maintenance port, apply power to the antenna unit. 2. Record the system serial number for later re-entry (the serial number is listed at the beginning of the startup sequence, as shown in Appendix F on page 143). 3. Disconnect power from the antenna unit and the IRD. 4. Remove the PCB cover, as explained in “Removing the Main PCB Cover” on page 106. 5. Disconnect all Molex connectors from the main PCB (see Figure 5-3). Main PCB Azimuth Motor Power/Data Fuses Elevation Motor Maintenance Refer to Section 4.6, “Computer Diagnostics” on page 98 for complete details on connecting a PC to the system via the maintenance port. Figure 5-3 Main PCB Connector Locations (Rear View) Cable Wrap (External Sensor) to RF PCB Antenna Gyro Azimuth/Elevation Limit Switches 54-0147 107 TracVision G4 Technical Manual TracVision G4 Technical Manual Figure 5-4 Main PCB Mounting (Top View) 6. Remove the nine #6-32 screws that secure the PCB to the antenna frame (see Figure 5-4). Support Frame Main PCB 7. Remove the PCB from the antenna frame. 8. Reverse this process to install the replacement PCB. Reconnect all connectors removed in Step 5. 9. Reinstall the PCB cover. 10. Apply power to the antenna unit. 11. Type HALT ( indicates a carriage return/ ENTER key). 12. Type DEBUGON. 13. Type =TVG4. 14. Type =SERNUM,, where = the system serial number you recorded in Step 2. 15. Type ZAP to restart/reinitialize the system. 16. Calibrate the antenna gyro as explained in “Calibrating the Antenna Gyro” on page 112. 17. Reinstall your selected satellites as directed in Section 2.9, “Installing Satellites Using the ADCU” on page 44. 108 54-0147 Maintenance Maintenance Two 5x20 mm, 3.15-amp, 250-volt fast-blow fuses are mounted to the main PCB (see Figure 5-3 on page 107). If one of these fuses has blown or been broken, simply remove the bad fuse and replace with a good fuse of the same rating. 5.5 Replacing the RF PCB 1. The RF PCB receives operating voltages from both the main PCB and the IRD (via the RF cable). Ensure that all power (including the IRD) is turned off before proceeding. 2. Using a 5.16" socket wrench, remove the four nuts and washers securing the RF PCB cover (see Figure 5-5). Set the hardware and cover aside. Figure 5-5 RF PCB Cover RF PCB Mounting (Top View) Support Frame RF PCB 54-0147 109 TracVision G4 Technical Manual TracVision G4 Technical Manual RF PCB Connector Locations (Rear View) Figure 5-7 RF Cable Ferrules ... Failure to hold the ferrules tightly while loosening the RF connectors can result in damage to the cables and reduce the signal quality. 3. Unplug the Molex connectors from the RF PCB (see Figure 5-6). Standoff Molex Connectors RF Connectors 4. If the top RF cable is not already marked, label it so that the RF cables can later be plugged into the proper positions on the new PCB. 5. Using a 7.16" wrench, carefully remove the two RF cables from the RF PCB. Hold the RF connector ferrules while loosening the connectors to avoid excess stress on or twisting of the cables (see Figure 5-7). 6. Using a 1.4" nut driver/socket, remove the four 11.16" standoffs and set aside. 7. Remove the old RF PCB. 8. Install the new RF PCB, making certain to align the PCB so that the RF connectors are facing inward (see Figure 5-1 on page 105). 9. Apply a drop of Loctite to one end of the four 11.16" standoffs. Install the four standoffs, Loctiteapplied ends facing the RF PCB. Secure in place using the nut driver. 10. Reattach the RF cables, making certain to connect them in their original positions (marked cable on top). 11. Reattach the Molex connectors to the RF PCB. 12. Insert the split rubber grommet surrounding the Molex connector cables into the small slot on the new RF PCB cover. 13. Secure the RF PCB cover using the nuts and washers removed in Step 2. Maintenance Maintenance 6 Replacing the Antenna Gyro Assembly 1. Remove the main PCB cover, as described in “Removing the Main PCB Cover” on page 106. 2. Using a 3.8" nut driver/socket, remove the four nuts and washers securing the antenna gyro to the reflector bracket (see Figure 5-8). The nut on the bottom right also secures a cable clamp. Set the nuts, washers, and cable clamp aside. Figure 5-8 Replacing the Antenna Gyro Assembly Gask et Br ac k e t Gyro 3. Disconnect the antenna gyro Molex connector from the main PCB (see Figure 5-3 on page 107). Remove the old antenna gyro assembly. 4. Connect the new antenna gyro’s Molex connector Make sure the cable passes through the PCB access slot to to the main PCB. protect the wires from the edge of 5. Replace the antenna gyro gasket (see Figure 5-8). the PCB frame. 54-0147 111 TracVision G4 Technical Manual TracVision G4 Technical Manual When rotating the antenna by hand, go slowly! Hitting the mechanical stops with excessive force will damage ...
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