Sea Tel ST144-21 - Page 86

Maintenance and Troubleshooting ST144-21 C/Ku-Band TVRO
13-10
• Modem Configuration
Verify BDE modem and ADE modem are properly configured (jumper block settings).
• ACU to BDE modem interface cable failure
Verify harness continuity. Repair or replace as required
• ACU Antenna Port Failure
o Install an RS232 Loopback connector** on Antenna Port of the ACU. Enter
an “n0999” Remote Command and verify that it echoes back on the bottom
line of the display.
1. If loop back works, BDE Modem failure or ACU to BDE Interface
cable failure.
2. If loop back does not work, ACU failure.
13.6.3.1.4.
• Modem Configuration
ADE No Response 1: (assumes LED illumination on both
modems)
Verify BDE modem and ADE modem are properly configured (jumper block settings).
o Install Spectrum Analyzer in line with the Rx IF coax path.
1. If 465.0MHz Transmit Beacon is present, the fault is the BDE
modem.
2. If 465.0MHz Transmit Beacon is NOT present fault is with the
ADE modem.
13.6.3.1.5.
• ADE Modem Configuration
ADE No Response 2:
Verify the ADE modem is properly configured (jumper block settings).
• Coax Cable failure
Verify continuity on the items listed below, repair or replace as required.
o Base Modem to connector bracket (Base Rack Panel Assembly)
o (CFE) BDE to ADE Rx (LMR-400)
o Rx N to SMA Adapter (Connector bracket at Radome base)
o SMA to SMA connector bracket to bottom side rotary joint
o SMA to SMA top side rotary joint to PCU/ADE Modem
• Rotary Joint (Receive channel)
Verify continuity on the receive channel for its entire 360 degree range of motion.
Replace rotary joint if any sector of it has failed.
13.6.3.1.6.
• BDE Modem Rx Port Failure (Not receiving at 465.0MHz) or
BDE Receive Or ADE Transmit (PED M&C):
• ADE Modem Tx Port Failure (Not transmitting at 465.0MHz)
o Install Spectrum Analyzer in line with the Rx IF coax path.
1. If 465.0MHz Transmit Beacon is present, the fault is the BDE
modem.
2. If 465.0MHz Transmit Beacon is NOT present fault is with the
ADE modem.
13.6.3.1.7.
• BDE Modem Tx Port Failure (Not transmitting at 452.5MHz) or
BDE Transmit or ADE Receive (PED M&C):
• ADE Modem Rx Port Failure (Not receiving at 452.50MHz)
o Install Spectrum Analyzer in line with the Rx IF coax path.
1. If 452.5MHz Transmit Beacon is present, the fault is the BDE
modem.
2. If 452.5MHz Transmit Beacon is NOT present, the fault is with
the ADE modem.