Consumers - SB6120: Troubleshooting Information

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SB6120: Troubleshooting Information

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How do I troubleshoot connectivity issues with my SB6120?
If Internet connection issues with the SB6120 arise, troubleshooting may resolve the issue, or may provide insight as to what is causing the issue.  This document provides helpful information for troubleshooting connection issues with the SB6120.
The document contains the following sections, to be followed in sequence:
  1. Checking the physical connection
  2. Verifying the LEDs
  3. Verifying the cable signal
  4. Power Reset
  5. Factory Reset

If the solutions provided in this document do not resolve the issue, please contact the cable operator.

Checking the physical connection

  1. Verify that the SB6120 power cord is connected from the power port of the SB6120 to the power outlet.
  2. Verify that the coaxial cable is connected from the cable port of the SB6120 to the cable outlet.
  3. Verify that the Ethernet cable is connected from the Ethernet port on the SB6120 to the Ethernet port on the computer.


Verifying the LEDs

With the proper setup, the Online LED should be solid green, and the Link LED should either be amber or blue. If this is not the behavior that the SB6120 is displaying, please refer to this table for more information regarding LED behavior.
 OffFlashingSolid GreenSolid BlueSolid Amber
POWERNo power to deviceN/AModem is powered upN/AN/A
RECEIVEReceive channel not found

Scanning for a receive (downstream) channel connection.Downstream channel is connected.Downstream channel is connected with bonded channels.N/A
SENDSend channel not foundScanning for a send (upstream) channel connection.Upstream channel is connected.Upstream channel is connected with bonded channels.N/A
ONLINEInternet connection failedScanning for Network ConnectionConnected to the InternetN/AN/A
LINKNo connection to the modem's Ethernet port detectedTransmitting or receiving data on Ethernet portN/AComputer is connected via a Gigabit (1000 mbps) Ethernet portComputer is connected via a 10 mbps or 100 mbps Ethernet port

Verifying the cable signal

  1. Launch a web browser, such as Internet Explorer, Firefox, or Safari.  Enter into the address box.  The Cable Modem Status page appears.


  2. Click the Signal link on top of the page.  The Signal page appears.

These levels apply to all Motorola cable modems and cable modem/gateways.  These values are absolutes.  If the cable modem is experiencing levels that approach the minimum or maximum acceptable levels, then it is a warning sign that there is a possible cable plant issue.  If the cable connection at the modem is OK, then it is advised to contact the cable operator to address the issue.

Acceptable Signal Levels (per channel)

Downstream Power Level (DPL):+15 to -15dBmV
Downstream Signal to Noise Ratio (SNR):23.5 dB or greater (if 64 QAM)
30 dB or greater (if 256 QAM and DPL = -5 to +15 dB)
33 dB or greater (if 256 QAM and DPL = -6 to -15 dB)
Upstream Transmit Power Level:57dBmV or less (1 downstream channel)
54dBmV or less (2 downstream channels)
51dBmV or less (3 or more downstream channels)



Power Reset

  1. Shutdown the computer.
  2. Unplug the cable modem from the AC wall outlet and wait one minute.
  3. Plug the cable modem into the wall outlet.
  4. Wait until the Power, Receive, Send, and Online LEDs are solid.
  5. Restart the computer.

Factory Reset

  1. Disconnect the coaxial cable.
  2. Power cycle the unit by disconnecting the power cord for 10 seconds, then reconnect the power cord.

    User-added image
  3. Launch a web browser, such as Internet Explorer, Firefox, or Safari.  Enter into the address box.  The Status page will appear.

  4. Click the Configuration link on top. The Configuraton page will appear.

  5. Click the Reset All Defaults button (as shown below).


  6. When asked, Do you want to proceed?, click the OK button.  The modem will reset to it's factory state, and will go through the initialization process.

  7. Connect the coaxial cable to the modem.

    NOTE: The initialization process may take 5 to 30 minutes.



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