Comcast / Motorola sb5100 cable modem dropping connection...

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I have broadband cable internet service from Comcast and I've been very
happy with it until this past week. I've been having intermitant
service to the net and it's really bugging me! It will work fine and
the online light will be on the external modem and then it will just be
off and no internet for my family (and biz). Then, it will just come
back on again after a few minutes, maybe stay on for hours then off
again for awhile.

I've talked to Comcast and we did a powerdown reset on the computer and
modem and he could tell on his end what my modem was trying to do (but
not succeeding in doing = to get online) and he said that the signal
was good to the house and that many people on my street were on at that
very moment w/o any complaints. He had me test the cable channels and
they were all fine as well. A new (mega thick) line was run to our
house just a few months back (worked fine after the cable was
installed). So he said it must be the modem.

We own our modem so they offered to have us signup for their rental
service ($3?/mo) but he wasn't sure if there would be a service
/installation fee to deliver and set it up. I told him I'd just buy
another one myself.

Am I smart in doing this or should I just pay their fee and have them
do it so the servicing is all on them? I worry (and have heard about)
about them using some cheap modems that actually don't work as reliably
or as fast as the Moto Surfboard SB5100 that I now have. Yes, the irony
of that last staement about my modem being reliable has hit me!

I have some info (an error log and some specific numbers but I'm not
sure which ones are relevent here) from a Motorola diagnostics site if
that could help anybody help me.

Before I fork over my money on a new modem could it be anything else?

Thanks so much for the help!!!!


Re: Comcast / Motorola sb5100 cable modem dropping connection...


On 10 May 2006 05:37:36 -0700, b4serenity@gmail.com wrote:

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They always say that... Don't take that as a given, as the tech you're
speaking to has no idea what other people are complaining about.

Ask your neighbors if they're having the same problem.

A_C

Re: Comcast / Motorola sb5100 cable modem dropping connection...


Can you access the modem to see the levels yourself?


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Re: Comcast / Motorola sb5100 cable modem dropping connection...


Does any of this help any?

/////////////////////////////
Downstream     Value
Frequency     687000000 Hz Locked
Signal to Noise Ratio     36 dB
Power Level     -10 dBmV
The Downstream Power Level reading is a snapshot taken at the time this
page was requested. Please Reload/Refresh this Page for a new reading

Upstream     Value
Channel ID     3
Frequency     31000000 Hz Ranged
Power Level     52 dBmV
////////////////////////////////////

ERROR LOG
Time     Priority     Code     Message
2006-05-10 13:34:47     3-Critical     R005.0     Started Unicast Maintenance
Ranging - No Response received - T3 time-out
2006-05-10 12:24:22     3-Critical     R002.0     No Ranging Response received -
T3 time-out
2006-05-10 12:23:57     3-Critical     T001.0     SYNC Timing Synchronization
failure - Failed to acquire QAM/QPSK symbol timing
2006-05-10 12:23:43     3-Critical     D005.0     TFTP failed - request sent -
No Response
2006-05-10 12:22:33     3-Critical     R007.0     Unicast Ranging Received Abort
Response - Re- initializing MAC
2006-05-10 12:21:54     3-Critical     R002.0     No Ranging Response received -
T3 time-out


Re: Comcast / Motorola sb5100 cable modem dropping connection...


On 10 May 2006 12:16:22 -0700, b4serenity@gmail.com wrote:
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at a glance you seem to be riding on the end of the power level specs.  
Here are suggested working ranges for solid operation. Values are from mine:

Motorola Surboard SB5120 QAM 256        (Working range)
Down Power -4 dBmV                      (-10 and +10 dBmV)
SNR 37 dB                               (higher than 33dB)
Up Power 48 dBmV                        (30 and 55dBmV)


Anytime you lose the connection, get the values.

Re: Comcast / Motorola sb5100 cable modem dropping connection...


First of all thanks so much for the help!!

I only get these values when I'm online by connecting to a Moto site I
saw in one of these posts. When my modem goes ofline I can't get these
numbers

Does it look like the modem is bad or is it saying that I'm getting a
fairly weak (barely strong enough) signal?


Thanks again!!


Re: Comcast / Motorola sb5100 cable modem dropping connection...


OK, maybe we're on to something. I checked all the connections again
but this time ran the cable to the modem directly from the wall w/o
going through the splitter that they installed when they hooked up my
dvr box in the same room. My down power level went up 3 dbs to -7.
Seems a little low but not right on the bottom like it was. I'll try it
like this for awhile and see if I get dropped. Maybe the modem is
actually fine and they need to do something about the signal splitter.

On the signal splitter it says 2-way splitter 5-1000mhzand on each of
the two split connectors it says -3.5 db. Not sure what that means
exactly but is it a coincidence that my signal rose 3 db w/o it? Can I
just get a different value splitter?

Thanks agin!!

John


Re: Comcast / Motorola sb5100 cable modem dropping connection...


b4serenity@gmail.com wrote:

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You should have a splitter coming into the house and you want the
cable modem to go direct to that splitter using preferably RG6.

Run your TVs off the other legs of that splitter (you may even use
another splitter off one of the TV lines [I do] without any major
issues).

As far as the TV in the same room as the modem, I'd run another
RG6 line for it.

Basically you want nothing else on your modem leg.

Re: Comcast / Motorola sb5100 cable modem dropping connection...



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SBill - PMFJI. I have a similar setup, viz., incoming feed split into
two  -3.5db channels.

Question: Can I install an amplifier on the non-modem channel to feed  
three TVs in the house, or will that cause problems? I've wired the
modem line with a 50' length of RG6, but haven't actually hooked up my
SF5120 as yet and called Comcast to set up service.

TIA

George

--
I know that you believe that you understood what you think I said, but I am
not sure you realize that what you heard is not what I meant.
            -- Robert McCloskey, State Department spokesman (attributed)

Re: Comcast / Motorola sb5100 cable modem dropping connection...


George Berger wrote:

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I don't see why not, but i'm running 3 TV legs off my 1-4 splitter and one
of the legs has a 1-8 splitter on it feeding 7 TVs/VCRs/PCs and I have no
problems with it.  You may not need an amplifier.

You may want to check some of the websites out devoted to this sort of
thing - like broadbandreports.com etc.

Re: Comcast / Motorola sb5100 cable modem dropping connection...



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Hi. Thanks! I'll go there

Cheers, George

--
I know that you believe that you understood what you think I said, but I am
not sure you realize that what you heard is not what I meant.
            -- Robert McCloskey, State Department spokesman (attributed)

Re: Comcast / Motorola sb5100 cable modem dropping connection...


While the -10dBmV downstream is perfectly fine, I would be a little
concerned about the +52dBmV transmit level.  Two possibilities are:
    1) Temperature.  It is possible that as the day progresses, the
increase in temperature increases the attenuation of the cable
sufficiently to push that transmit power beyond its limit, which
typically is about 56-58dBmV.

    2) At some point, noise is getting into the return path, which causes
your cable modem to transmit at a higher level than it otherwise would.
  The 2 biggest types of noise that can disrupt the upstream path are
ingress and impulse noise.  Ingress is stuff leaking into the cable
system from the outside world.  The most common causes of leakage are
loose/substandard/corroded connectors, poorly shielded cable,
substandard passive devices (splitters, taps).  These are all part of
the drop system.  Impulse noise can be electrical noise getting into the
cable system if there is insufficient filtering at some point where the
2 have something to do with each other, such as a cable modem plugged
directly into a wall outlet without the benefit of a surge power strip.
  Vacuum cleaners and blow dryers (things that cause sparklies on your
TV when turned on) are also sources of impulse noise.

Something is causing your cable modem to shout loud enough to be heard
by the CMTS.  Sounds like sometimes it has to shout so loud that it
can't be heard.

I would call and have a tech come out and figure out why your transmit
is as high as it is.


CIAO!

Ed N.

b4serenity@gmail.com wrote:
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Re: Comcast / Motorola sb5100 cable modem dropping connection...


Redid some splitters/connections. So far I'm still online just fine and
here are the newest readings:
Downstream     Value
Frequency     687000000 Hz Locked
Signal to Noise Ratio     38 dB
Power Level     -2 dBmV
The Downstream Power Level reading is a snapshot taken at the time this
page was requested. Please Reload/Refresh this Page for a new reading

Upstream     Value
Channel ID     3
Frequency     31000000 Hz Ranged
Power Level     44 dBmV


Re: Comcast / Motorola sb5100 cable modem dropping connection...


That 44dBmV is a beautiful thing!


CIAO!

Ed N.

b4serenity@gmail.com wrote:
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Re: Comcast / Motorola sb5100 cable modem dropping connection...


Yes, those are all good levels.


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Re: Comcast / Motorola sb5100 cable modem dropping connection...


Well, I've been offline again for the last few hours again. If those
numbers are good then I THINK I have basically eliminated the signal
/wiring problem... so it's probably my modem?


Re: Comcast / Motorola sb5100 cable modem dropping connection...


I had a similar situation a couple years ago.   Everything was fine and then
it'd go offline for 15 minutes to a few hours.  Of course, when I reported
it they'd schedule a service call and all would be well by the time he
showed up 2 days later.   Later another outage and the same problem.   I
finally got so frustrated that I went to the local Comcast office, spoke to
the manager and described my frustration.  She contacted the local
maintenance manager who called me to discuss it.   They finally realized
they had an amp with an intermittent noise problem.   They changed the amp
and it hasn't happened since.

If I were you, I'd be escalating the issue and talking to a higher level of
management.   In that kind of situation the normal trouble reporting process
is unlikely to work and you'll have to become the squeaky wheel.  I'd keep
escalating until you get someone's attention.

That's just my two cents worth.......


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Re: Comcast / Motorola sb5100 cable modem dropping connection...


I just talked with others on my street w/ comcast net service and
they've been fine. So, now that, with the fairly OK signal strength
shown, has me thinking more then ever that it's probably the modem.
I'll give it a shot and see if that does the trick. If it doesn't fix
it then s the ball will be back in comcast's court.


Re: Comcast / Motorola sb5100 cable modem dropping connection...


I had a situation that started around the end of January that nobody
could figure out.  Talked with my assistant state engineer a few times
about it and nothing made any sense.  Levels were great and S/N was
great also.  Download speeds suddenly dropped to about 1/3 of what they
were previously.  Swapped the modem out with one I had previously with
no change.  Upload was not affected, just download.  Went on for a
couple of months.  Eventually, a Chief Tech in Indiana mentioned
something.  I bought a new cable modem and voila, back in business.


CIAO!

Ed N.

b4serenity@gmail.com wrote:
Quoted text here. Click to load it

Re: Comcast / Motorola sb5100 cable modem dropping connection...


No new modem yet but here's the latest error log;  Does this indicate a
bad signal from Comcast or still possibly a Modem problem? Any help
appreciated!!

Time     Priority     Code     Message
2006-05-12 17:46:54     3-Critical     R002.0     No Ranging Response received -
T3 time-out
2006-05-12 17:46:44     3-Critical     T001.0     SYNC Timing Synchronization
failure - Failed to acquire QAM/QPSK symbol timing
2006-05-12 17:46:24     3-Critical     R002.0     No Ranging Response received -
T3 time-out
2006-05-12 17:46:04     3-Critical     R007.0     Unicast Ranging Received Abort
Response - Re- initializing MAC
2006-05-12 17:45:47     3-Critical     R002.0     No Ranging Response received -
T3 time-out
2006-05-12 17:45:42     3-Critical     T001.0     SYNC Timing Synchronization
failure - Failed to acquire QAM/QPSK symbol timing
2006-05-12 17:45:21     3-Critical     R002.0     No Ranging Response received -
T3 time-out
2006-05-12 17:45:07     3-Critical     R007.0     Unicast Ranging Received Abort
Response - Re- initializing MAC
2006-05-12 17:44:49     3-Critical     R002.0     No Ranging Response received -
T3 time-out
2006-05-12 17:44:43     3-Critical     R007.0     Unicast Ranging Received Abort
Response - Re- initializing MAC
2006-05-12 17:41:28     3-Critical     R005.0     Started Unicast Maintenance
Ranging - No Response received - T3 time-out
2006-05-12 13:25:23     3-Critical     T001.0     SYNC Timing Synchronization
failure - Failed to acquire QAM/QPSK symbol timing
2006-05-12 13:25:19     3-Critical     T002.0     SYNC Timing Synchronization
failure - Failed to acquire FEC framing
2006-05-12 13:25:19     3-Critical     T001.0     SYNC Timing Synchronization
failure - Failed to acquire QAM/QPSK symbol timing
2006-05-12 13:25:14     3-Critical     T002.0     SYNC Timing Synchronization
failure - Failed to acquire FEC framing
2006-05-12 13:25:12     3-Critical     T001.0     SYNC Timing Synchronization
failure - Failed to acquire QAM/QPSK symbol timing
2006-05-12 13:25:12     3-Critical     T002.0     SYNC Timing Synchronization
failure - Failed to acquire FEC framing
2006-05-12 13:25:11     3-Critical     T001.0     SYNC Timing Synchronizatio


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