DBAS Codenoll - Tech Support

Troubleshooting 8391

If the CodeNet 8391's POWER (PWR) LED doesn't illuminate it means that the unit is not receiving power from the DTE. In this case, the problem may be one of the following:

  • NO power from DTE. Indicates wrong port setting on Ethernet controllers with multiple media options.
  • Defective DTE
  • Defective extension cable.
  • Defective 8391 transceiver.

    Troubleshooting -- Review the installation instructions, check to see that your transceiver is properly installed and securely fastened.

    1. Ensure that the DTE equipement is powered up, and set to AUI mode.
    2. Ensure that the bulkhead-mounted slide latch on the electrical connector is properly installed.
    3. If using a transceiver cable, verify that proper transceiver cable is being used. That it contains no shorts or opens and that the cable length doesn't exceed 50 meters. Swap transceiver cable to isolate a potentially defective cable.

    If these steps have been taken, the POWER LED should illuminate. If possible, use a known good 8391 to isolate a potentially defective 8391. Check the Ethernet controller by swapping with a known good AUI card. If the problem is not alleviated you may try replacing the entire unit.

    If the CodeNet 8391 LINK INTEGRITY (LI) LED does not illuminate when the optical fibers are connected, this means that the 8391 receiver is not receiving an IDLE signal from the companion unit. The problem may be one of the following:

  • The half-sleeves have not been installed to the SMA 906 connectors (if used). Doesn't apply to ST and SMA 905 connectors.
  • The companion unit isn't powered up.
  • The fiber is broken, or there is excessive optical loss in the fiber.
  • The companion unit is defective.
  • The 8391 is defective.

    Excessive optical loss may be due to one or more of the following:

  • Dirty connector ends.
  • Connector installation which exceeds manufacturer loss specs.

    In this event, you should...

    1. For SMA 906 connectors, verify that the half length alignment sleeves are installed over the tips of the fiber optic cable connectors.

    2. Check that the Transmit port is connected to the receive port of the companion device and vice versa.

    3. Verify that the optical fiber cables are securely connected to their respective optical connectors and that they aren't broken. A flashlight is an excellent continuity check for breaks. If the link is normal, light should be observed at the other end. An optical source like the idle signal produced by the 8391 (non-visible light) and power meter may also be used. Replace or repair the cable, if a fault is found.

    4. Verify that the optical link loss doesn't exceed the CodeNet 8391's optical receiver sensitivity. This may be determined by using an optical power meter (CodeNet CTC 2000 or equivalent) to measure the optical power. If the average power on the received fiber at either end (measuring the optical idle signal) is less than -30 dBm the problem is in the fiber, or in the transmitter of the companion unit.

    5. Then, measure the output power of the companion unit's transmitter by using an optical power meter with a known good fiber optic jumper cable. If the output power is within specs, the problem is in the fiber connecting the two devices.

    If the green LINK INTEGRITY LED is ON (Norman operation), but the DTE unit can't connect to the network, or transmit valid Ethernet packets, the following may be the problem:

  • Network break somewhere else is the network.

  • Heartbeat switch is On in either the 8391 or the companion unit and is attached to a repeater.

  • Companion unit's receive circuit is defective.

  • Network software (or monitor) is not properly installed.

    In this event, you should...

    1. Check the indicator lights of the companion unit visually or from the appropriate network management station.

    2. If the companion device is a hub, check that the port has not been disabled (PARTITIONED).

    3. Check that the companiom unit's LINK INTEGRITY indicator is ON. The lack of a LINK INTEGRITY indication on the companion unit indicates a fault in the 8391 Transmit path.

    4. In Active Star configuration, check continuity between hub and the server by connecting another known good fiber optic node, using the same port. This will isolate the network problem.

    5. Ensure that controller (AUI) card is properly seated in DTE slot.

    6. Swap AUI card with a known good AUI card.

    7. Swap 8391, then its companion with a known good 8391.

    8. Ensure 8391 switches are in factory settings.

    9. If an 8391 is attached to a repeater, or another hub, ensure that its heartbeat switch is off.

    If these steps don't solve the problem, recheck the installation software or E-Mail Us.

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