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Doc · Guest

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

Michael Walraven · Guest

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

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Homer J Simpson · Guest

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