Alpha Technologies USM2.5 Status Monitor - Manual (Page 22)

6. Troubleshooting
22 704-683-B0-004, Rev. D
6.1 Troubleshooting the Communications Link
Occasionally the communications link between the XM Series 2 power supply and the headend
site may appear to break down. Updates to and from the power supply may not take place,
or data received may be faulty. When this happens, isolate and correct the failed elements in
a precise fashion to avoid extended troubleshooting times or the possibility spreading a
potential failure from site to site.
Symptom: No Remote Control (Inverter Test)
Diagnosis: To start, verify that USM2.5 J4-11 (Test/Reset) are HIGH; change
state via remote command pins should go LOW.
Repair Solution: If the remote commands are present, goes from HIGH to LOW,
replace the USM2.5; if not, troubleshoot the transponder and RF
section.
Symptom: Incorrect Scaling voltage reported.
Diagnosis: Verify that the USM2.5 is configured correctly; then verify the
XM2 Output in question; verify USM2.5 scaling.
Repair Solution: If the scaling voltage reported is NOT correct, replace the
USM2.5. If scaling voltages are correct, troubleshoot the
transponder and RF section.
Symptom: Status monitoring reports “Comm Error”.
Diagnosis: Verify that the USM2.5 is correctly connected to the transponder,
and that the transponder is correctly powered (per transponder
documentation).
Repair Solution: Correct connections as needed.
Symptom: No Auxiliary DC output
Diagnosis: Verify Auxiliary DC output by checking voltage on J4-2 with the
USM2.5 disconnected from the status monitor; if voltage is
correct, reconnect status monitor and check again.
Repair Solution: With the USM2.5 disconnected from the transponder the
Auxiliary DC voltage is NOT correct, replace the USM2.5. If AUX
DC voltages is correct with transponder, troubleshoot the
transponder and RF section.