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joedadog 07-02-2006 10:01 PM

Checking Cable line
Is it possible to check a cable line with an ohm "multi" meter to see if there is a signal? I have four lines coming in my family room, and I want to see which is "live" without hooking it to a TV. Any help would be great. thanks.

toussi1 07-26-2006 02:56 PM

hook a 9V battery to one end and then test with ohm meter to see which is live.

HomeAV 11-17-2006 02:58 AM

I think you would be better off with using a DMM (Digital Multi Meter) with the DC voltage setting. An ohm meter is used to measure resistance not voltage.


Originally Posted by toussi1 (Post 14900)
hook a 9V battery to one end and then test with ohm meter to see which is live.

gregzoll 01-20-2007 08:42 PM

Not really. Unless you are using a RF meter, you cannot do it with a Ohm meter, or Volt Meter.

Brik 01-22-2007 03:31 PM

If you know which cable it is on the outside of the house, or basement or where ever and can disconnect that end. You can then short from the center pin to the shield. At the other end use an ohm meter to check for continuity between pin and shield. The one that has it is the cable you are seeking.

gregzoll 01-22-2007 05:28 PM

That will not work, due to if the line goes into a splitter, you could end up reading the wrong line. Plus, it is not the true method of testing the line.

Brik 01-22-2007 05:35 PM

If it goes to a splitter it will still work. Yea an RF meter but how many have those lying around. You can find them online for about $100. You can also get the line type testers for about $65 that will do this. Also a phone cable tracer would also work. Lots of ways. The ohm meter is just one way and doesn't involve any cost if the OP has one which I assume they do since asking about multimeters.

hyper 02-18-2007 03:22 PM

The easiest solution for what you are doing is to use a tv. I know you mentioned doing this without a tv, but its really the easiest solution.

elementx440 02-19-2007 07:31 PM

i dont understand, people will sit here and post/respond for days trying to shortcut, when they could have just picked up a tv from another room, and tested it in 10 minutes....

oh, and you should use an o-scope :)

gregzoll 02-19-2007 08:02 PM

Because, not everyone is going to have a small portable T.V. set to drag off to another room. Could you imagine someone trying to haul a 60" HD set from one room to another by themself.

Soundbroker 02-21-2007 03:50 PM

If you don't have access to the other ends of the cable then a 9 volt battery (voltage meter) or shorting the cable (Ohm meter) won't do you much good. If you do, both will work fine.
Two things you can try if you don't have access to the other end and don't want to drag a set into the room...

First off, if you have a cable modem, bring it in and hook it up see if it gets a connection. Lot more portable than a TV.

Second thing to try is if you have a cable box, hook it in and see if you can change channels. Again, more portable than a TV.

gregzoll 02-21-2007 09:26 PM

Thanks for the laugh, but that will not work. The only real way to find out, is to either have the CATV company show up with the proper equipment to check everything out, or just hook up the line to a splitter, and see if you get a pic. The only problem is, if the input is not marked, it can be hard to find out, without touching the tip and shield to feel the tingle, or use a meter to be safe, due to lines can carry a electrical charge, that can cause problems if found to be an ungrounded CATV system (ie TV's blow, etc.).

Soundbroker 02-22-2007 12:13 AM

Sure it will work, I've been doing HT installs for 27 years and I've used both methods successfully. Using a cable modem will work fine if they already have existing cable modem service in the house. I did this on an install a few months back on a theater I designed in SLC Utah. There were 5 input lines on a basement floor equipment closet where the prewire crew forgot to mark the input drop in that part of the house. We grabbed their cable modem from the upstairs and started plugging...the hot line got the connection. Many digital cable boxes also need to register at the head end to get any information, so again...many will only work if you have a signal present. The one that gets the clock display or allows you to change channels is probably hot. Plug the box in without any cable attached to see if it brings up a clock display or changes channels...chances are it won't.

One other thing not mentioned is to use a long length of cable and an inline coupler and hook the long cable to a set in another room then swap connections until you get the signal. This assumes you have a long length of RG6/RG59 and an F to F.

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