← incident filesTKT-60003 · MT Ulvik · T-1040 · opened 14 Oct 2026, 03:40 UTC

Outside the known fault list

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Customer report
MT Ulvik

“Internet is down on board since about 02:30 UTC. The modem lights look different from usual.”

Diagnosis

LNB (receive-side ODU) failure on T-1040. LNB current has collapsed to 0.02 A against a nominal 0.25-0.45 A, and syslog flags lnb=low from 02:30. Rx lock was lost at the same moment, so tx is disabled and the terminal is not logged on. Pointing, BUC, GPS and the rest of the beam are normal. This is not in the fault list; it is closest to an ODU hardware fault, so reported as unknown.

T-1040
Evidence
  1. system.log 02:15:54 lnb=ok, 02:30:37 lnb=low, and lnb=low on every sample since
  2. show rf: LNB Current 0.02 A (nominal 0.25-0.45 A); BUC 1.79 A / 40 C normal
  3. modem.log 02:30:34 'ERR rx lock lost' and 'WARN tx disabled: no outroute lock'; show modem: Rx Lock NO, Es/No -5.0, NOT LOGGED ON
  4. acu.log: point_err 0.04-0.12 deg (limit 0.5) throughout, but state=SEARCHING and sig dropped from ~70% to ~35% at 02:30. This is consistent with a lost LNB signal path rather than mispointing
  5. Fleet data: the other 9 terminals on B4 are online with normal Es/No, so it is not a beam outage
  6. GPS 3D fix with 8 satellites, no reboots (uptime 17d), temperatures normal
Evidence gaps
  1. No LNB-specific log beyond the lnb=ok/low flag and the current reading, so it is not possible to separate a failed LNB from a faulty or damaged coax/F-connector or the LNB power feed from the modem. Both need on-site checks.
  2. The ACU log shows SEARCHING with low signal even though pointing error is small. This is probably a side effect of the lost LNB signal, but ACU behaviour was not separately verified.
Next steps
  1. Dispatch a technician with a spare LNB and a spare Rx coax cable and connectors.
  2. On board, check the Rx coax and connectors for damage or water ingress, and check the LNB power feed from the modem (about 0.3 A expected).
  3. Replace the LNB if the cable is good and the LNB current stays near 0.
  4. After the repair, confirm rx lock, Es/No near 9.8 dB, network logon and that tx resumes.
  5. Tell the customer that the modem lights are showing rx lock lost and that it is a hardware fault on the antenna's receive side, not a LAN issue.
Investigation

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