Checks at the Central Office

  • For express power models, do not draw power from a line with dial tone. The loop extender power supply must be fed by no less than 16 AWG wire to work properly.

  • Is the power supply grounded?  The power supply ground is for dumping surges to ground.  Do not attach to frame ground.

  • Check the output of the power supply, do you get 116vDC or 155vDC (depending on model)?  

  • Sometimes SNR margin and sync rate settings can conspire to prevent synchronization. The bandwidth estimate is based on SNR Margin=6. If your SNR is higher, you will get slower connect speeds. If your SNR is much higher than 10, you may have difficulties in getting connections on long loops. If it is lower than 6, your customer will complain about data errors and resync.

  • If you are using the line power extender, check that there are no leakage currents on the line.  With no loop extender on the line, current should be essentially zero.  With a line powered loop extender, you will read 4-4.2mA.  You might read 6-6.2mA if the loop extender has been switched to high power mode.

Checks at the Pedestal

  • Verify that you are getting 116vDC or 155vDC (Depending on model) on the power pair with no load (disconnected from the blue pair of the loop extender). When attached to the extender, power should be diminished by no more than 1-2v per thousand feet.

  • DO NOT put the power supply in the pedestal.

  • Is the LED on the Loop Extender on? 

  • Is the Loop Extender grounded? Bonded? The ground, cable sheath, loop extender and power ground should all be bonded together at the loop extender and as frequently as possible elsewhere.  Lack of bonding will allow significant interference from AC power, AM radio, electric fences and similar problems.

  • Does the loop resistance and attenuation match the numbers predicted by the ADSL Bandwidth Estimator? Check both power pair and service pair. If not, re-check distances, connections and eliminate loads.

  • Does modem sync at the pedestal without the loop extender connected? The sync rate at this location is the maximum the extender can deliver down range. If you can't get sync, the loop extender will not work at this location. You must clean up the line so that you get sync nearly matching the rate predicted by the ADSL Bandwidth Estimator

Checks at the Customer Premise

  • Does the modem run without errors?

  • Does the modem report SNR Margin=6 to 10? The bandwidth estimate is based on SNR Margin=6. If your SNR is higher, you will get slower connect speeds. If your SNR is much higher than 10, you may have difficulties in getting connections on long loops. If it is lower than 6, your customer will complain about CRC errors