Alpha Technologies USM2 - Manual (Page 27)

27
©2000 ™
704-587-B0-003 Rev.D
6. Troubleshooting
6.1 Troubleshooting the Communications Link
Occasionally the communications link between the XM2 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 possibly spreading a potential
failure from site to site.
Symptom: No Remote Control (Inverter Test)
Diagnosis: To start, verify that USM2 J3-11 (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; if not, troubleshoot the transponder and RF section.
Symptom: Incorrect Scaling voltage reported.
Diagnosis: Verify that the USM2 is configured correctly; then verify the XM2 Output in
question; verify USM2 scaling.
Repair Solution: If the scaling voltage reported is NOT correct, replace the USM2. If scaling
voltages are correct, troubleshoot the transponder and RF section.
Symptom: Status monitoring reports “Comm Error”
Diagnosis: Verify that the USM2 is correctly connected to the transponder, and that the
transponder is correctly connected to the RF section.
Repair Solution: Correct connections as needed.
Symptom: No Auxiliary DC output
Diagnosis: Verify Auxiliary DC output by checking voltage on J3-2 with the USM2
disconnected from the status monitor; if voltage is correct, reconnect status m o n i t o r
and check again.
Repair Solution: With the USM2 disconnected from the transponder the Auxiliary DC voltage is
NOT correct, replace the USM2. If AUX DC voltages is correct with transponder,
troubleshoot the transponder and RF section.