Hi All,
My question to the forum is how to know when you are putting an excess load on the cable line? I am starting to see a problem with my SD TV signal and my Cable modem for the high-speed internet. The system in my house is layed out like this. I have a 2-way splitter in the attic with one output running to the cable modem and the other output to the first TV location. At the first TV drop, I have a 4-way splitter that has the first TV, a Tivo, and a VCR located in the basement with a TV on the output of that. The last connection on the 4-way is empty. The problem I have is the cable modem drops off line every now and then and I pick up a few bad channels (not all) on the TV's with this system hook up. If I take the TV/VCR combo off the 4-way things, get better and work. Do I need to run an amp off the one leg to the TV's on the first splitter or do I need a filter at this point? I can give you folks more info on the signal off the cable modem if it's needed. The cable system is Time Waner and the second TV/VCR combo was install a few weeks back and is about the time this problem started.

I had the tech out to the house and he found a few problems outside the house that he fixed but I'm not crazy about letting him in my house. I would rather fix this myself if I can. What he did helped but it's still not 100%.

Thanks for any help,
Steve

Does the problem remain if you remove devices that are not the TV/VCR combo? If no, your fault is isolated to those devices.

Perhaps they're excessively noisy.

Hi Cybe,

If I run just the cable modem I have no issues. That's taking out all the extras other then the modem. If I put things back on one by one then I get to the TV/VCR combo and the problem starts back up. The other part of the problem is that it issues will not happen right away (sometimes a few days sometimes a few hours) and usually brings the cable modem down when it happens. I'm going to replace the splitters and the cable Modem which is a 6 year old Motorola Surfboard SB4200 unit and see if that helps. I was wondering what the normal Downstream Power level would look like in dBmv on a cable system?

TIA

Your nominal D/S power level at your cable modem should be about 0dbmv this can range from -10 to +10 (approx) ideally 0dbmv is a good level.

If removing the TV/VCR combo fixes your problem you have isolated it.
If you remove everything (but the cable modem) and only have the TV/VCR does the problem occur?
Is the unused port of your 4 way terminated?
If not go to Radio Shack and purchase a 75ohm type F termination.

I would let the Time Warner cable tech in the house to correct the problem.

I think I got it fixed. I had ground issues on the feed into the house. The cable modem has worked well for the last 24 hours. :) The connection on the outside of the house was corroded really bad. When the tech stopped out last week he found a piece of the cable that was chewed up by a squirrel on the pole. He never checked the point going into the house. My modem signal numbers look like this.

Downstream
Frequency 117000000 Hz
Signal To Noise Ratio 36.3 dB
Power Level 0.9 dBmV

Upstream Value
Channel ID 1
Frequency 33000000 Hz
Power 45.0 dBmV

Let me know if this looks amiss but everything is working smooth now. :)

Thanks for the reply's.
2Dog

You should be fine , that line being chewed is never good. Seems like the tech got it.