Motorola SB5120 / Optimum Online Problem - Need help.

Hello all...

I have an old 3Com CMX modem that I wanted to upgrade. I went to CompUSA and brought a new Surfboard SB5120 modem. I brought it home, plugged it in and waited... and waited.. and waited....

The modem would never come online. The first three lights, Power, Send, Receive were a steady green. The fourth light, the "Online" light, just flashed... and flashed.... and flashed...

I called Optimum Online Customer Service who told me I had a defective modem. They did, take my new Mac address, had me reset the modem, etc, to no avail. They ran a signal test and came up with:

SNR: 34Db Power Level Downstram: 4dbmV Power Level Upstream: 50dbMV

I returned the modem and picked up a second one. Plugged it in, turned it on, etc. Same problem. I went to the diagnostics page of the modem and the signal was as follows:

Freq: 6030000000 Hz SNR: 34db QAM 256 Network Access Control Object: On Power level: 4dbmv

for downstream.

For upstream:

Channel ID: 3 Freq: 25008000 Hz Range Id: 5335 Symbol Rate: 2.560 Msym/s Power level: 50dbmV

I went to the STATUS page on the diagnostics and saw that the modem was hanging on the "Registering connection" step. It would hang there for about 5 minutes and restart the process all over again.

Optimum Customer Support gave me the run-around. First, I was told it was a bad signal, although the specs above seem to be ok. Also, my old cable modem was working fine and after I plugged it back in, I was back online with the old modem in 5 minutes flat. After the tech checked my signal with the old modem, and said it was fine, he said the modem was bad.

Can someone tell me what is going on here? I've had TWO SB5120 modems that were supposedly bad, and quite honestly, I'm not buying it. I suspect there was some sort of problem on Optimum's end, but I couldn't get anyone who was willing to help. The answer to every question was either "we need to send a tech out" or "your signal is bad".

I want to upgrade to the SB5120 so I can take advantage of higher speeds. Am I out of luck? Is there that big a difference between the SB5120 and the SBV5120? Optimum tech support told me both should work, but that the SB5120 just didn't have the VoIP, which I'm not using anyway.

Can someone help?



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Your Tx levels are elevated: Power level: 50dbmV

This can be caused by a couple of things:

Split TV/HSI signals Damaged Cables Bad Signal from supplier

The key thing to have your ISP do is check your neighbors TX levels on the same node...if all customers are high, then they have a plant issue

Hope this helps.


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Kenneth J. Harris


I never made it that far. Cablevision claims they couldn't see the new modem hooked up to the line. When I put my old modem back on, they found it immediately.

I don't get what the problem is.... maybe the modem has to be from Cablevision?

Anyone else have any other suggestions?


Kenneth J. Harris wrote:

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