Home cabling - any experts out there?

Factual Questions
1

I’m trying to get the (coax) cabling in my house to behave. I’ve lived in the house 4 years, but it has never quite worked as it should.

My house is a 3 story townhouse, built in the 1980s. Let’s call the floors L1 (basement), L2 (bedrooms), L3 (living).

Here’s what I know:

  • The “tap” (where the cable arrives from the street) is on L2 in the master bedroom.
  • From there, it hits a splitter - one “leg” goes upstairs to L3, one goes downstairs to L1.
  • There is a cable outlet in each of the 2 guest bedrooms; neither of these outlets is ‘live’, i.e. it doesn’t see the signal from the cable company.
  • However, the two outlets in the bedrooms are connected to each other - I verified this by hooking up a TV / VCR.
  • Upstairs on L3, where the cable arrives, behind the wall plate there is another cable that leads downwards inside the wall, but I haven’t been able to find out what it’s connected to. I hooked up a VCR to it, and tried hooking a TV to the cable outlets in the guest bedrooms, but no dice.

There is very little access to cabling in my place - everything’s hidden inside walls, with no access panels. My girlfriend points out that the cabling almost definitely worked when the house was built - the previous owners must have split, cut or otherwise mutilated it since then.

My goal is to figure out how to get the outlets in the two guest bedrooms to “see” the signal.

I have Googled the hell out of this - the only vaguely useful site I found was a page on DSL Reports which explained the difference between a “loop” and a “home run” topology. I’m pretty sure I have a loop.

As a bonus question - are there any tools that help in a situation like this? How would an experienced cable guy tackle it? I was thinking of something like a signal generator, and some kind of detector for tracing the cable through the walls.

Thanks for any help. This is driving me nuts. When the cable guy came out a couple years back, his “solution” was to drape a wire around the baseboards with tacks.

Here’s a little diagram in case it helps:



                    ------------------------------------------
L3                  | Signal OK from L2.       +-------- cable going nowhere?
                    ---------------|--------------------------
L2 cable from street --+  Main     |   B1 --+-- B2           |
                    ---------------|--------------------------
L1                  |  Basement - signal OK from L2          |
                    ------------------------------------------

B1 & B2 have no signal but are connected to each other.
2

The usual way to find the other end of a mystery cable is to short the centre wire to the shielding and then test the possibilities for the other end with a multimeter for continuity between centre wire and shielding. I don’t know of any way of detecting the actual wire with instruments. You could try rattling it back and forth and have someone listen for where it makes noise, but that’s iffy at best.

Question: is the ceiling in the basement finished with drywall?

3

Excellent idea on the shorting thing - I thought of putting a current through it then testing with a multimeter but that one’s better.

Regarding the basement: it’s a “suspended ceiling” so relatively accessible - there is a bunch of infrastructure in there. I don’t recall seeing any extra cable wires - just the one leading down from L2 - but I will take another look.

4

You can buy cable toner kits from almost any RadioShack-type store. These consist of a “toner box” and “toner buttons” which usually have caps of different colors. Let me give you an example of how I used to use these in new home satellite installations.

Generally, when a house is initially wired up for cable/satellite television, all coaxial cables are run from each room to a central “maintenance” location either inside the house or outside. Your house may be different and YMMV.

Our first step was to place the toner buttons (which have a male prong (F-connector)) on each coaxial outlet in each room. For example, BR1 would have the yellow TB, BR2 red, BR3 brown, and so on.

Next, we would go to the central location and hook each coaxial cable (with F-connector) onto the toner box (which has a coaxial “outlet” extending from the top) and press the “TONE” button. An LED would light up on the toner box to indicate which TB was detected (ie. yellow, red, brown, etc…) therefore we would know what cable went to what room. If, on the other hand, the coaxial cable connected did not have a TB on the other end, an LED would indicate that as well.

These devices cost somewhere around $30-40.

If those two bedrooms are connected to each other, but not connected to the rest of the home’s coaxial network, the only remedy is to either fish a connecting cable down the wall to one of those bedrooms or as the cable guy suggested ick stapling the coaxial cable to the baseboard.

Hopefully some of this info will help.
Good luck!

LiQUiD

5

Suspended ceiling is good. Here’s my suggestion if you can’t find a cable running into one of the boxes in the guest bedrooms.

Drill up through the basement ceiling into the wall where the cable outlet in one of the guest bedrooms is. This may require some careful measuring to locate. You want to make sure your drill comes out in the same studspace as the cable outlet. You should then be able to push a wire up through that hole and fish it into the outlet. You may have to remove the electrical box to do this, assuming there is one. Try not to wreck the drywall pulling it out. Once you have a line into the guest bedroom, you can run it back into the outlet in the master bedroom using the same technique and patch it in with a splitter there, or, if it’s easier, find the line heading to the existing basement outlet and T into it (assuming you have the crimpers and ends to terminate coax and can do this).

It’s almost never necessary to run wire on the surface. There are just varying degrees of difficulty in hiding it. :slight_smile:

6

First question-is the splitter located outside at a master cable demarc box, or is it inside the dwelling? How many outputs does the splitter have? If only three, then the original plan was to send 1 output to each level. Checking behind the master bedroom wall plate, you may find a secondary splitter to feed other locations which may not have been hooked up. Before trying to fish anything, I’d remove all of the wall plates and see if extra unconnected wiring exists, like what you found on L3.

7

Agreed. Question: Does Co-ax loose “power” as the legnth increases?

8

Yes. Ohm’s Law applies as usual. Increased length of cable equals greater resistance equals less current flow. This is unlikely to be an issue for cable running inside a single house, though. At least, unlikely to be an issue for television reception. Cable modems can be pickier about signal levels.

9

I second the idea with the toner kit. It may cost you $20-$30 bucks. I used to work for Time Warner and they save your ass when it’s location-oriented. However, few of the guys actually knew how to trouble-shoot cable. Instead they would just run more since they didn’t have to actually install it unless it needed to be wall-fished. As far as tools go, the above mentioned toner and multimeter, a pair of kleins, a twist-style wire stripper for usually both RG-59(thicker coax) & RG-6 (thinner; less shielding) and a connector crimp tool. In my experience, replacing the end connectors usually improved things, especially if the center conductor or the dielectic is showing some wear.

Who knows perhaps you can “trick” your local cable guy to come out and look at a particular leg of your cable. Most cable guys are pretty generous if you ask for extra coax (since we don’t pay for it :D). Possibly you could get some easier runs done over for you- but no wall-fishes unless you’re willing to pay for it. If you are capable of doing your own wall-fishes then you might get some a lot of the work done for you and then you could fish the cables later, I suggest you protect the connectors some way (even tape or better a loose seperate other end to the coax to screw in for the wall-fish.

I guess what it comes down to is how much you want to spend or study-up with. Good luck with it. Try searching for: coax, RG-59, anatomy of Coaxial cable, coaxial installation-again good luck:)

10

Aside from the ‘toner button’ thing, you can also get a tone generator with an inductive probe that will help you locate wires. You put the tone generator on one end of the cable, and then you can run the inductive pickup along the outside of a cable bundle and find which cable is which. These are typically used where many cables terminate in the same area and you don’t know which one goes to which outlet. These would be of limited to no use in find the cable from outside the wall, because generally the pickup has to be within a couple of inches of the cable before you can hear the tone. If, however, you just want to find out where the wire at the splitter terminates, this would work fine. Just unscrew the cable from the splitter, screw it onto the tone generator and turn it on, then go from room to room with the pickup. Just press it against the cable, and if you hear the tone, you found the right one. Home Depot sells one of these tone generator sets for about $50.

The cheap and easy way to do it would be to get a 9v battery with a battery clip and pigtails. Clip the pigtails onto the cable (one on the center conductor, one on the outer shield), then go from room to room with a voltmeter, touching the probes to the center conductor and shield. When you pick up 9v, you found the cable.

Cables do attenuate, but not enough that there would be NO signal at the other end. If you see a snowy picture but you at least get a picture, then you could replace the passive splitter with an RF amplified splitter and solve that problem.

It’s entirely possible that someone accidentally cut or pinned the cable hanging a picture or something, so that may be your problem. There are fancy tools you get that you can put on the end of a cable and they’ll actually tell you how many feet it is to an open circuit, but that won’t necessarily help you if you don’t know the route the cable takes in the first place.

TV cables should always be end-run back to the entry point to the building, but in older homes you’ll sometimes find a cable outlet added to a room by putting a splitter on the cable on the other side of the wall or on the closest existing jack. Someone may have done that for your bedrooms and the connection has come loose. Since you say the two outlets in the bedroom are tied together, that seems likely.

If you can afford it, your best solution might be to hire someone to come in and pull new cables for you. Or, you can pull them yourself. depending on the house, it can be very easy or terribly difficult. It really depends. Sometimes you can take cables through the cold air return that runs between floors, or you can pull a cable up into the attic and then from there across to the room you want and down inside the wall.

11

Another couple pieces of advice: don’t skimp on the splitters or the ends you put on the cable.

People generally get the crimp-on connectors becaue the tool is cheaper and it’s hard to stomach spending $45 for a tool you might use for one day every 5 years, but compression-style connectors are much less of a headache. With crimp-on, you never really know if it’s on there well, and when you’re troubleshooting a noisy line because your cable modem won’t connect, you might as well lop off the ends and put new ones on, because they could be the source of the noise. With compression, you get a nice, solid connection that you can tug on without worrying about damaging it.

And a splitter is not a splitter. Look for splitters with their signal loss value in dB printed on them. You don’t have to necessarily care what the value is, but know that if it’s not printed on there, it’s because it’s not very good. :slight_smile: As a rule of thumb, don’t buy the cheapest one in the store. It will make a difference.

Oh, and one more thing: it makes a difference where you split a cable. If you cascade two-way splitters so you split one leg more than the other, you end up with a lopsided tree where one side has much greater signal loss than the other. If you need 8 taps and you start with an 8-way splitter, that’s generally the most efficient use of your signal. As an example, if you take your signal and put a two-way splitter on it, then put another two-way on one of those legs, then a third two-way on one of the legs of the second splitter, you get 4 taps. The first tap has half the original signal power, the second has 1/4, and the 3rd and 4th each have 1/8 (in theory – they actually have less due to losses in splitting). Whereas if you run the cable into a 4-way splitter, you get 4 taps with 1/4 of the signal power each.

12

It may be off topic, but do not run your cable through an air duct!
It may be easy early on, but I haven’t seen anything more ghetto looking as a half-ass cable install (like a leg of coax coming out of an air vent).

One, if the air ducting actually needs to be serviced (leave it to fate) you’re only complicating things. 2) and more importantly, the only decent looking run, going through an air duct would require you to drill a hole at the top inside the duct and place a protective grommet in the hole of the duct as not to damage the coax then run your cable to where you would come up @, even then you’re still stuck with reason one. Galt makes a good point with with splitter quality, although I found it pretty much a given that people know splitters “leak” more signal than if you never had to patch two ends together via a splitter.

Also, a toner kit and a tone generator are the same thing Sam Stone, one end is the power/generator and the other is simply a speaker to touch to the center conductors in question and make a tone. And personally I’ve toned a cable clear across a house before, not a few inches.

While much of cable installation tools are not worth the price a cheaply bought “ebay toner” will be useful again and again (at least in my experience) to find your leads or to get an easy favor from your neighbor/family member/friend (helping them find their cable leads :rolleyes: )

13

Wow, thanks for the great advice guys. I’m going to print this thread out and break out the MCM electronics catalog :slight_smile: As always I’m overwhelmed by the depth and quality of knowledge of Dopers.

I spoke to my neighbor yesterday (has a near-identical townhome to mine). He said something about, when the units were originally built, the cables were run through the walls, but then the cable company did their own thing, using their own cables, but without hooking up the bedrooms. In other words, he seems to have the same issue as me. Weird.

14

Just wanted to correct Thinktank’s response:

RG6 is the thick cable; RG59 is the thinner variety. You want RG6 as RG59 has severe loss at the frequencies at which digital cable and cable modems operate (there’s a chart somewhere on broadbandreports.com, but I’m too lazy to look for it).

In general, a two way splitter will be 3.5 dB down on each leg; that is 3dB for splitting the signal in half, and .5 dB of loss (more or less). A 4 way is 7 dB down on each leg, and a 3 way is 3.5dB down on one leg and 7dB down on the other two.

I suggest you contact your cable company; they may give you inexpensive (or free) wire, splitters and plugs; or if you happen to see an installer near your house, ask him/her. It is in their best interest for you to have the best quality wiring, since in theory your bad wiring can affect someone else’s signal. When I had cable installed in my house a couple of years ago, I told the regional tech manager (who was on site due to some difficulties we had) that I was going to be rewiring everything through the walls, and he instructed the tech to give me almost a full box of wire, plus a plethora of plugs and splitters…

15

Who said anything about pulling coax out of an air vent?

Going through the cold air return is a common way of moving cables between floors in houses when there’s no other easy way to do it. It’s not a heat duct, it’s just the return. And yes, you need to put in a grommet, but that’s easier than drilling through the footer, firebreaks, and header of a wall to get into the space above, and if the walls don’t line up, that may not even work. As for having to make the seal airtight, well, cold air returns aren’t particularly air tight anyway. A lot of homes have cold air returns made by simply stapling tin between floor joists to make a plenum, and the return between floors may simply be an open space inside the wall where there are no firebreaks.

16

Whenever you run any type of cabling in a plenum, e.g. an air handling space, the insulation of said wiring must be plenum rated. Typically these cables are teflon or kynar insulated to greatly reduce ignition potential and smoke production.

17

As a side note, this is just a guess, but looking at the diagram above I’d speculate that the reason for that “unattached” hunk of coax on L3 is probably a remanant of an over-the-air antenna hookup. Being that it’s the top floor and the “living” space, I’d suppose that in the years before cable (or in the more recent, or more cost conscious years) a previous owner had installed an antenna and fished coax through the wall into L3. Being that they may have only had one TV, from here there was little need to extend the lines from there.

As for that second strange connection on L2. I’m guessing, as has been posted here, that the two jacks actually aren’t connected to one another or were by mistake. The other possibility is that the previous owner simply used the two jacks as a way to hide a segment of cable, mjust not all of it. They had a TV hooked up in B1, and a splitter on the floor which ran into the jack. The wire concealed the cabling to B2.

Not that these things help you too much, but just a couple thoughts.

18

Apologies for the cable mix-up DarrenS, RWScissors is dead-on this one, sounds like the instructor I had when I first joined-up…in other words, it’s been a bit.

Personally, I would buy me a four port signal booster, patch all existing connections through that and then run a fresh line over to your bedrooms regardless of whether there’s a “mystery coax” in there somewhere.

Coax ages even more than what most specifications say. I’ll take a fresh run over a years old run of coax any day. Also, as said by others and myself, fitting new connectors to the ends will give you better picture 95% of the time.

As far as the bedrooms go, it’s up to you whether you want to replace the loop or not; usually these kinds of bedrooms in houses are reserved for guests or children so nobody sweats the quality so much as the master BRM or the living area.

19

I like the idea of the 4-port signal booster. Is there a good place online to buy those? The best I’ve found for that kind of stuff seems to be MCM electronics, but their online catalog is pretty poor.

Assuming I do that, I’m guessing I need a 2-way device for my cable modem, right? Also, assuming I decide to run new coax through the walls (rather than tacking it along the baseboard, ghetto-style), is there a standard or easier way to do this, rather than ripping out yards of drywall?

20

My dad is cheap, but his set-up seems to work ok.
I’m sure he just went to Radioshack or Walmart or what have you and checked the specs printed on the packaging. He’s an Electronic Engineer, so i’m sure he knows how to string his budget along. I believe his booster is made by Archer- lol… (just your run of the mill electronics co.) He’s got cable modem too… So to follow his plan you would “T” off the primary line. One goes to your modem (you can’t boost cable modem with a standard booster, if at all) and one to the booster which splits off the remaining lines.

As for new line, I think checking your houseplan and wall fishing this would be a worthwhile endeavor (could just be me) …if you give-up on doing this yourself you might wanna pay the 50-75 bucks to get it done for you. I’ve fished through firebreaks and all the rest of that crap one of the fellas up there mentioned… homes these days are made so… “differently”.
Just go to your local grocery store and see if you can’t “borrow” a few strands of bail wire… the thicker the better.

If none of that sounds even the least bit appealing I guess you can always try under the carpet. I’ve installed it this way for some people and it didn’t look too bad, of course it’ll take either a hole in the floor on both sides (to go under the wall and back up under the carpet on the other side) or a hole through the bedroom walls. With enough cosmetic parts it can be made to look ok.

Of course it you’re going through the floor twice the previous way, it only begs the question "why not abandon the whole rig and just run a fresh line under the house and up through the floor into the rooms you want cable in or if you have 2 people take off the outlet find something long to tap with (to slide inside the wall to the floor) and tap while your buddy is under the house with the drill then you can run the new line into your existing loop and connect it all inside the wall.

A few ideas, hope one of them closes this subject out for you.
Just be creative and see what you’ve got to work with(tools, walls, crevices and angles), you’d be surprised where a piece of coax can go :smiley: