Good sound; intermittent picture.

Have you tried replacing the coax? It seems to me for a couple of bucks, you can avoid a lot of effort if it works.

The antenna connector could be loose, or corroded. If you have any DeOxit, put a drop on the end of a toothpick and clean the center contact of the antenna socket. If it's an F connector, which is designed for bare wire as the center contact use something thinner, like a bent paperclip.

Geoff.

If by "loses its picture" you mean that the picture abruptly and completely dissappears, with no effect at all on the sound, I'd say "no".

If that's the effect you're seeing, then I'd suspect an intermittent fault in the set, either a defective connector, or a dry joint, which gets nudged so as to form a connection for a while when you tug at the cable.

Sylvia.

I've replaced it in that the guy who gave me the tv had the very same problem with his coax and his location.

I can get it or something like it.

Yes, an F-connector. Okay, I'll do that, but is it really conceivalbe that a bad connection there will affect the blank out the picture but leave the sound undamaged? I hope so.

Yes, exactly.

I'll look for that. The TV is so big (25") I need to make a lot of room on the work bench, and before I do t hat it will work fine for 2 days.

But the clues fropm the two of you should speed things up when I do try to fix it. Being a basement cowboy is not so great after all.

Thanks, and iI think I forgot to thank Geoffrey. Thanks, G.

The very same problem and the very same remedy. He got the picture back by jiggling or moving the coax.

In my experience, as the signal level is reduced on an analogue CRT television, first the picture becomes grainy, and then, as the signal gets worse, the picture becomes unstable as well. There is no particular level at which the picture is gone, it just merges gradually with the noise.

Sylvia.

when you wiggle the coax, are you putting any!!!!! strain on the printed circuit board inside????

TV tuner? So is that tuner putting out TV signal on channel 3? Or is it putting out separate audio and video (more likely)? Is there more than one connection between the two? Audio tuner and separate audio sound system?

Boy, am I stupid. Ifnore my first answer. I thought you described the problem here. I thought that was the problem when I first posted.

But in reality, maybe the picture is still there. It's just so dark often nothing can be seen but little blue and red hyphen-shapped lights blinking on for an est. 20th of a second, and then bliniking on somewhere else around the screen. Hundreds of them at any one time.

At the same time, when closed captioning is on, it looks perfect, white and bright and the letters fully formed.

Not tonight, but I recall that sometimes the picture can almost be seen, like it is night time, with most of it black and maybe part, maybe the background, very very dark blue or very very dark red, barely one shade lighter than black. I guess when the real color isn't blue or red, it just looks like black.

I guess my memory is going. Sorrry.

DVDR with tuner and hard drive. In the bedroom.

Yes, that's it. .

No. I think it has audio and video outputs on the back of it, but when I put in the wiring for the other rooms, I didn't think to put in more than one co-ax line. But it's working fine in the kitchen. Only this tv in the basement is intermittent. .

No. Everything is on that one co-ax line.

Thanks.

If I recall correctly, as the modulation gets stronger, the picture gets darker. Of course the tuner/IF system had AGC, which will try to maintain an adequate signal output as the strength of the input signal changes. And some sets were designed to blank the screen (or put up a blue screen) if the input signal was below adequate levels. However, I can't see any reason to believe that that is happening in this case.

By far, the most likely situation is that there is a bad solder joint in the video processing area AFTER the audio subcarrier is extracted. Given the level of integration in modern TVs, the tuner and IF strip could be integrated into a single mackage. As such, it is unlikely that replacing the RF input would fix anything.

By the deacription, it's unlikely it's the high voltage.

There are a number of sources for schematics and even complete service manuals online. One of the better ones is Elektrotanya.com.

PlainBill

You said the previous owner of the television was seeing the same behaviour. Did he also have what is now your DVDR unit connected?

It's not clear what role the DVDR unit is playing here. If it's tuning an analogue channel, and just frequency shifting it, then the closed captioning would have to be generated by the TV. In that case, there is clearly a fault somewhere in the between the TV's own tuner, and where the closed captioning gets superimposed on the picture.

On the other hand, if the DVDR unit is tuning a digital channel, and providing an analogue output, complete with closed captioning, then it's hard to see that there can be anything wrong with the TV at all, with the problem lying in the DVDR unit, which is, after all, connected to the other end of the coax that you waggle.

That really sounds to me as if the DVDR unit is just frequency shifting an analogue channel, and that there's a faulty connection or dry joint in the video signal path in the TV - a small amount of the signal gets through by the capacitance of the failed connection.

Sylvia.

My own exact DVDR? No. He was a stranger who gave the TV to me via Freecycle. He just said the picture went out peroiodically and he got it back by moving the cable that went into the TV.

I have no analogue channels, just over the air channels.

Yeah, but I have 3 other TVs I watch daily that never have problems

The bad one is in the basement, the good ones in the bedroom, the bathroom, and the kitchen. The DVDR is in the bedroom.and the bedroom tv gets the signal first. Then the basement TV with the problem, after after that the signal goes to the kitchen TV which has no problems.

(There's an amplified splitter that sends the signal to the bathroom and the bedroom/office, but the computer is broken so I spend a lot of time in the basement trying to fix it and using a basement computer)

What I can do to test this is try to watch a movie on the VCR, which sits next to the DVDR and is connected in parallel by an A-B switch.

I also have a digital conversion set-top box feeding the VCR, so maybe I'll just watch television via the box/VCR. I'll do that tonight.

Thanks a lot.

I noted each point you made, both exclusions and leads. . I didn't knjw about Elektrotanya.

Thanks!