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Arris TM822 voltage levels after reset near limits

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Arris TM822 voltage levels after reset near limits

Periodically my modem has an intermittent internet connection.  About three weeks ago, a technician visited the house and the internal wiring in the house is excellent.  He said there was an issue outside of the house.  He scheduled a line man to check it out.  I never heard back from the technician.  Everything was fine until yesterday.  I called Comcast and the person said there was an issue with my modem (self-owned) and to call Arris.  Arris showed me how to access the limited information on 192.168.100.1 and how to reset.  The transmit voltages were above 51 (51.5) on one channel before reset.  Attached are the levels today and everything is working okay.  If the outside impedance is too high, would the modem increase the transmit voltage to levels that are out of spec?  Is the transmit SNR is too low and the voltage are reset to levels near the top of the limit in order to compensate?  How do I resolve where the problem is?

StatusTM822--5-19-18.png
Regular Contributor

Re: Arris TM822 voltage levels after reset near limits

How many splitters are used between the line coming in and the modem.

All your levels look good except for the upstream power. It is best to be around 42-45dbmv on there, 48-49 max, and 50+ can cause problems.

Expert

Re: Arris TM822 voltage levels after reset near limits

@goldfreaz

 

Since you've already had a tech visit...

 

I've asked an employee to check the CMTS for real-time and historical RF signal reports from your modem. They can also check your local node/plant for any degradation or error reports. You can expect a reply in this thread. 


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Expert

Re: Arris TM822 voltage levels after reset near limits


@goldfreaz wrote:

  If the outside impedance is too high, would the modem increase the transmit voltage to levels that are out of spec?  Is the transmit SNR is too low and the voltage are reset to levels near the top of the limit in order to compensate?  How do I resolve where the problem is?


Yes, if the headend server can't "hear" the modem, it instructs the modem to increase its transmit power. If there is too much resistance, the modem won't be able to transmit and you'll see upstream failures. Typically this is caused by faulty or misconfigured wiring, which is why @FAUguy is asking you about splitters. This issue can be caused by other factors such as a bad line to your house or an issue on Comcast's physical plant. Presumably, your tech verified that the issue was not in your home and the repairs/adjustments should be made to the cable plant. 


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Official Employee

Re: Arris TM822 voltage levels after reset near limits

 

Hello goldfreaz, I can check into your signal levels and correct any issues in the line. Please send me a private message with your full name, street address, and account number by clicking on my name (ComcastAmir) and then "private message me".


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Frequent Visitor

Re: Arris TM822 voltage levels after reset near limits

All the internal cables were installed by Comcast about four years ago.  Only one splitter is inside and it has four output ports.  Only two ports are used, one to the modem and the other to the TV box.  It may be possible to replace this with a two output splitter to get the system a little less marginal.

Frequent Visitor

Re: Arris TM822 voltage levels after reset near limits

ComcastAmir promptly checked my modem and outside line reports.  All is in proper working order.

Official Employee

Re: Arris TM822 voltage levels after reset near limits

 

goldfreaz wrote: ComcastAmir promptly checked my modem and outside line reports.  All is in proper working order.

 

It was a pleasure assisting you, please reach back out to me if you need anything else. Have a good day. 


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