Maintenance And Troubleshooting; Maintenance; External Troubleshooting - Cable AML ITX21-100 Installation And Maintenance Manual

5.0 MAINTENANCE AND TROUBLESHOOTING

5.1 Maintenance

Maintenance is not normally required for the ITX21-100 after initial installation. However
input and output power levels should be measured periodically and adjustments made if
necessary.
The output power level should be measured and adjusted as described in Section 4.0 of
this manual. The VHF input levels should be verified before making significant
adjustments in the transmitter. If the VHF input level is correct and the transmitters output
cannot be set properly, external troubleshooting is necessary as described in the next
section.

5.2 External Troubleshooting

In the event of low or no output from the transmitter, first verify the following:
Verify the AC power input by checking the fan on the transmitter for motion. If not
1.
operating then check the line fuse on the back panel.
Frequency and level of the VHF input.
2.
•
Incorrect input frequencies may produce output frequencies that are unable
to pass through the two filters or the power amplifier.
If these items are found acceptable, check the VHF Transmitter Monitor output:
With the selector switch in the INPUT position, the output will be a replica of the
1.
VHF input signals, but about 20 dB lower. If the Transmitter Monitor INPUT
selection produces low or no output, recheck item #1 above.
With the selector switch in the OUTPUT position, the output should be a replica of
2.
the VHF input signals, but about 5-10 dB higher. If the Transmitter Monitor OUTPUT
selection produces low or no output, check the DC diagnostics on the front panel
meter.
DC Diagnostics (Figure 4 lists expected values for each function)
NO +12 VDC. Internal troubleshooting is necessary.
If source tuning does not eliminate the transmitter output malfunction then internal
troubleshooting is necessary.
IM4030013-1 Rev –
Indoor Broadband Transmitter – ITX21-100
15