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Can a coax connection be partially damaged? Some stations suddenly not coming in on HDTV on coax in.

An older friend asked me to hook up their DVD player to their HDTV via the component cables. Yes, not complex but again, they're older and somewhat technophobic.

I got the DVD hooked up to HD1 and in fact it plays the DVD when HD1 is selected. However, now, some of the stations that were coming in on their coax cable connection aren't. They've got this HDTV hooked up via a coax cable coming through the VCR - yes, I know, complete waste of technology but that's their setup. In essence, they're just using it as a wide screen tv and don't seem to care that they're not getting an HD picture.

However, now he tells me that some of the stations don't come in that had been coming in before. At first, I thought maybe in the process of moving the TV around I had damaged the coax connector but some of the stations come in strong when the cable is connected - only snow without the cable so obviously a signal getting through. The stations that now don't come in on this TV do come in on other TV's in other rooms on the same cable system.

Can you think of reason why some stations wouldn't come in only on this one tv when they were before? Since I'm not an electronics buff, I wondered if there was a way for a coax connection - either the cable or something in the tv to be "selectively broken".

Additionally, something odd I notice is that they have the cable from the wall going to the "out" coax connection on the DVD/VCR player and the cable to the tv from the "in", which I assumed was backwards. However, after reversing the cables, the picture is worse.....?? Doesn't seem right to me..

Unfortunately I was in town visiting for Thanksgiving, so am not able to do a hands-on look at what's going on now. I've suggested they try other TV's on that same cable and perhaps get help to lug this HDTV to a connection in another room to see if it exhibits the same behavior, which is I would do if I were there.

Also, unless they're taping off the cable connection, now that they've got the component cables hooked up from the DVD, there isn't any reason for the coax cable to go through the DVD/VCR is there? Or is there?

Thanks for all input

Reply to
Doc
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I've had a situation where the volume levels varied widely from channel to channel. Cured by twisting the coax connectors to wipe the contacts.

Reply to
Homer J Simpson

Yes a cable can be 'selective' in frequency. That said it is very UNLIKELY that is your problem. Problems occure on longish cables that have been damaged (something heavy placed on them, or partialy cut), kinked, or coiled too tightly. The result will be frequency dependent nulls in the transmission. Dirty connections can of course be a problem but are usually intermittent rather than selective.

Clue is in the VCR between the source and the TV. (Based on similar problem with an elderly lady I used to 'fix' things for .)

The VCR has two modes when considering the coax connections. In one mode the 'output' is connected to the internal electronics of the playback/tuner section of the VCR. In the other mode the 'output' is connected to the 'input', either electronically or with a relay.

When the mode is (sometimes labeled TV) then the TV RF signal goes directly from the IN to the OUT. When the mode is (sometimes labeled VCR) then the TV RF signal goes to the VCR electronics where is can be tuned and the OUT receives a reconstituted signal on a specific channel (3 or 4 usually but some will do a UHF channel also).

In my lady's case she would have the VCR on and in the VCR mode. She would complain that the picture was very poor on certain channels. She had a big outside antenna and so had some very strong signals and some fairly week signals. Inside the VCR the circuitry that isolates the IN from the OUT connector is usually not very good so a lot of leakage occurs even when in the wrong mode. So the result was that strong signals got thru with enough signal left to make a good picture and the weaker signals were reduced to pretty poor. I origionaly tried to get her to understand the difference in the modes but that was a loosing propsotion. I did get her to leave the VCR off, in most units that cause the IN to be connected to the OUT and the signal can get thru. (I couldn't just set it to TV mode for her because she unpluged everything when storms were in the area and when plugged back in the VCR went to the 'wrong' mode as default.)

OK that was the long version.

First thing to try when you go back is to connect the VCR OUT to the TV IN and try to play a tape. Picture should show up on some channel (3 or 4?) and maybe on component also. Then connect the coax from the wall directly to the TV and see if that works. It is possible that the auto scan for channels got hosed somehow when you were setting up the TV (Antenna mode vs Cable or wrong cable type for instance), so an automatic scan without the VCR involved would be good. Then back to the wall to the VCR IN and the TV to VCR OUT. Set the mode to 'TV' or something like that, (usually a front panel button, not some menu setup thing) hopefully that will get the channels back.

Until you go back, have them turn off the VCR and see if that helps until you get back. That should connect the OUT/IN connectors even if they are backward.

Does the VCR playback go out over the component cables? In that case you don't need the coax going thru the VCR portion but you might still want it so they can record on tape. Some combo units don't convert the VCR to component just to RF or Video (yellow) output.

As an aside, if the TV is HD with a digital tuner and they have an antenna (rather than cable TV) then they have a very good chance of getting HDTV. The TV may need to told that over-the-air digital is available and then allowed to scan for it.

Probably a whole lot more than you wanted!

Michael

Reply to
Michael Walraven

Most DVD/VCR players will disable any other outputs when you use the component connections. Mine does that. So if you decide to use component out, the coax out connection might be disabled and hence that's why now you can't get any channels.

Hook up the coax direct to the TV and you should get the channels back.

Reply to
Mikepier

here is a nice easy solution go to your homedepot or rad shack and buy a good 2 way splitter and hook the incoming canle to the input and one output directly to the hd tv and the other to the dvd/vcrs in. this will give the tv a much better so-called direct signal and yet the vcr will still get is signal for recording. then run the instalation for the auto search on the tv , making sure you have cable selected not antenna that should do the trick

Reply to
David Naylor

Also, as Michael said, make sure the CABLE/ANTENNA selection in the TV menu is correct. You won't get any channels above 13 if it is wrong.

The TV tuner is almost certainly better than the VCR tuner; so, you really don't want to use the VCR to tune the channels. If you do, the VCR also has to have the CABLE/ANTENNA selection set correctly.

Tam

Reply to
Tam/WB2TT

Not at all, you demonstrated a comprehension of what the problem is - and I'm glad anyone was willing to wade through the description of the issue.

Of course, telling them to actually get HD service would be impolitic but would make it a moot issue altogether. ;-)

Reply to
Doc

I was thinking the same things as mentioned by others but would add one for ya. From your description, I'm thinking they have a newer/recent model set that should have at least 2 inputs, coax and composite. (Actually, I'm thinking they'd also have at least one component and/or DVI/HDMI if that "HD1" and "wide screen tv" are true descriptors) Get a good splitter (-3.5dB,

5-1000Mhz, 2-way) Splitters can good bad too. Re-screw/tighten all connections. Place the VCR on its own input and "train" your friends to switch through the 3 sources/inputs - ANT/Cable coax, DVD, VTR. They'll have to learn anyway if they ever do get HD on that set.

PS - I always tell the technophobic some variation on - "Don't worry about being smart enough to use this computer. Computers are dumb and they'll do exactly what you tell them to do even if it is wrong." and "You don't have to worry about using this computer, you can't blow up the world by touching the wrong key." These TV's are minicomputers now too. Heck, if you can learn how to heat up a cold cup of coffee with a microwave, you can handle this.

YMMV

Reply to
MrMike6by9

You may want to also check for a backfeed voltage from tv to Vcr, or from vcr to tv. We in the cable industry have found a lot of big screen HDtvs and projections backfeed a small voltage to our HD cable boxes that can lead to loss of HD pictures, so I Imagine it could work both ways. It may also cause tiling or mosaics on the HD pictures.

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Dartattack
Reply to
Dartattack

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