After Installing Splitter my modem stops working

[bmwdriven]

Hey Guys, I have an issue here that hopefully you can help me with. I have a two seperate cable lines coming into my apartment. When AT&T installed my broadband I used one of those lines for just the cable internet and I left the other one for TV. I installed a tv tuner awhile back and with a 1 GHz splitter everything was fine. This was atleast 6 months ago. Yesterday I go to get on the web and the modem lights arent all on. I check the connections and they're fine so I take the splitter off the line and go straight into the modem and my internet service is back again. If I unplug the cable from the modem and go into the tv tuner card I get TV. At this point I know this service is fine so I figure the splitter burned out. I test the splitter by plugging my tv tuner into it and then to the wall and I have tv. Its a 2 way splitter and both sides test out fine. I dont know what the issue can now be.

Could my modem be on its way out? I have a Motorola SB4100. Could the splitter not be working correctly? I figurerd if the tv is working then the splitter is good. Also, are there special splitters to get? My friend just had broadband installed and they put in a splitter that was -3.5db and a had a AT&T sticker on it. The splitter I have is -4.0db and is just a standard splitter I picked up at Home Depot.His internet is working great and his tv quality is excellent.


Thanks guys for reading through this and lending your advice. One thing as well, how do you do a line quality test? I see some of you post these results in your questions.

[hellraiser]

I bet its the splitter I would pick one from you cable company.

[bmwdriven]

Yeah, thats what Ive been thinking. Im going to pick one up today and see how it goes..

[Kip Patterson]

The splitter may be bad, but another possibility is that the signal level on your line is such that the splitter reduces it below the level the modem can handle.

Why don't you use the diagnostic pages in your modem to see what the actual levels are?

Kip

[yearling]

Here's my experience on this. Normal splitters will not work with Cable modem and some signal amplifiers (at least in my case). Splitters should support at least 1Ghz or greater. Most splitters bought in RadioShack and Homedepot, etc operate under 1Ghz. So check the splitter before buying. As for signal amps, I always have a signal amps/splitter(powered) connected to my cable line to compensate for the number of drops I have at home. But when I had the Broadband Connection I had to remove the line going to the cable modem from the Signal amps' output and have to split the main line into 2, one to the modem and the other to the signal amp.

Try calling your provider they'll give you one and you'll not have to worry if it's going to work or not. Have fun!

yearling

[bmwdriven]

Thanks guys for the help thus far..

I just picked up a Monster Cable 2 Ghz splitter at Circuit City. It cost me about 20 bucks so I figurerd its the best one out there. Im at work till 8:00p.m. so I wont know how it works till then but Im hoping that it will fix the problem.

Kip, How do I run the diagnostic mode on the modem?

Thanks Guys..

[Kip Patterson]

A 2Ghz splitter is intended for satellite dishes and may not work with a cable system. The highest frequency on a cable system is 970 Mhz and your existing splitter should be fine.

The internal pages on a Motorola are at 192.168.100.1.

Kip

[bmwdriven]

The splitter says it does 1ghz and 2 ghz...I'll give it a try and see. Hopefully my current splitter is dead because it was working fine in the past.

[HarveyWG]

If you have lost the signal on your cable modem it may be that your signal level is too low after installing the spitter, and if that is the case your cable company should be able to have a tech do something to adjust the levels. It may also be though that the signal range on the splitter that you were using doesn't cover the full range of the spectrum that your cable company uses for signals for the modem that you have. As in the case of my cable company, the full signal range used on our system is from 5-1000Mhz, and many of the average Radio Shack splitter only cover from 50-900Mhz, cutting off the very high end of the signal, and the low end of the signal where the modem locks down onto the signal. I would look to see if your cable company gives out splitters, they will have ones that cover their full range.

[bmwdriven]

Originally posted by HarveyWG
If you have lost the signal on your cable modem it may be that your signal level is too low after installing the spitter, and if that is the case your cable company should be able to have a tech do something to adjust the levels. It may also be though that the signal range on the splitter that you were using doesn't cover the full range of the spectrum that your cable company uses for signals for the modem that you have. As in the case of my cable company, the full signal range used on our system is from 5-1000Mhz, and many of the average Radio Shack splitter only cover from 50-900Mhz, cutting off the very high end of the signal, and the low end of the signal where the modem locks down onto the signal. I would look to see if your cable company gives out splitters, they will have ones that cover their full range.

Harvey, thanks for your suggestion. My splitter was working fine for quite sometime now all of a sudden Im having this issue. In a few hours, I'll be able to test the new splitter and see if it restores my connection.

[MtCableman]

Originally posted by Kip Patterson
A 2Ghz splitter is intended for satellite dishes and may not work with a cable system. The highest frequency on a cable system is 970 Mhz and your existing splitter should be fine.

The internal pages on a Motorola are at 192.168.100.1.

Kip

Kip is right!

This splitteris made for satellite dishes and will not pass the upstream signal. The upstream signal is around 22Mhz and will not pass through this "satellite splitter". Get one from the cable company!

[bmwdriven]

The splitter did not make a difference. I think my signal strength is to low..

After entering in 192.168.100.1 this is what I got:

Downstream:
Frequency 693000000 Hz Locked
S/N ratio 34 db
QAM 64
Network Access Control Object ON
Power Level 13 dBmV

Upstream:
Channel ID 1
Frequency 38000000 Hz Ranged
Ranging Service ID 232
Symbol Rate 1.280 Msym/s
Power Level 58 dBmV

Are these good? I dont know...

The front of the splitter says it will work up to 2 ghz. It says that at 1 ghz it has a drop off of 3.5 db and that at 2 ghz it has a drop off of 4.9 db. I figured it would work at 1 ghz for the cable split. Oh well..

[legalmind]

Is there a reason you did not call the cable company?

[pseudoferret]

The power level that you is indicated is 58dBmv. This is the transmit level of the modem (or how loud it has to yell to get back to the router). The DOCSIS modem transmit range is 8-58dBmv, meaning that your modem is having to yell as loud as it can to get back.

A 2 way splitter causes 3.5dB of loss which would cause your modme to have to yell back at 61.5dBmv which it just can't do. You will need to contact your cable provider and have a technicain come out to check the return path.

Just as a side note, your downstream signal level shows as 13dBmv which is 2 shy of the high limit of the modems receive window which is +/-15dBmv.

Hope this helps.

[bmwdriven]

thanks psuedo for the explaination.

legal, my internet has been running smooth, I just started getting this issue when I tried to split the signal to go to a tv tuner card.

I guess I'll call the cable company tomorrow and get a technician out to the house. what should i tell them is the reason why they need to come out? The service is strong but Im a bit worried that my modem may die on me if its running at max strength.

[MtCableman]

Originally posted by bmwdriven
The splitter did not make a difference. I think my signal strength is to low..

After entering in 192.168.100.1 this is what I got:

Upstream:
Channel ID 1
Frequency 38000000 Hz Ranged
Ranging Service ID 232
Symbol Rate 1.280 Msym/s
Power Level 58 dBmV

Are these good? I dont know...

The power level is 58dBmv. That is a "real time" level. You don't add the loss of the splitter to that number. It is still too high though! You have a major return loss somwhere.

[bmwdriven]

Is there anything on my end you guys can suggest I do besides calling a tech?

[eddiec]

Here's an outside shot. Pull off the wall plate and see if the cable is split in the wall instead of out at the box. If it is, the just install a 3 way splitter there and pull 2 lines out for the tuner card and modem. Be aware that 2 ports will be rated at 7 or 8 and one will be 3.5 or 4. Use the lower rated port for the modem as your levels suggest using the lowest possible drop.
If that doesn't work, try running into a tech on the road and asking for a splitter rather than calling in to the office. Sometimes they'll want to charge for an additional line, even though it's a splitter. But if you have to buy one outright, go to a supply house for the cable, satellite and alarm contractors in your area. They will be able to get you the right one.

[crazyjw1971]

I would just call the cable man and have them find the problem. Those signal numbers... were they taken with the splitter or without the splitter?

[MtCableman]

Bypass the splitter and bring up the modem diagnostic page. See what the numbers are without the splitter. It did work without the splitter? Try to put everything back the way it was before you started having problems.