TV has a moving, thin horizontal line

[eckythump]

I have a toshiba 42h80 HI-DEF project which I've had for a few years. Now I'm having issues when watching HI-DEF 720p/1080i programming.

A thin horizontal line (maybe 10 pixels or so) moves up the screen. It used to be one, but now it's 3 or 4, moving up the screen always the same distance apart and it's each bar is getting bigger and more coulourfull!

Any ideas? I guess I'm going to need to call in a TV repair person but don't want to if they are going to charge me $100 to tell me I have to replace a "widget" which will cost $1000. If that's the case I'll buy a new TV.

Help!
Ecky

[passedpawn]

I have a toshiba 42h80 HI-DEF project which I've had for a few years. Now I'm having issues when watching HI-DEF 720p/1080i programming.

A thin horizontal line (maybe 10 pixels or so) moves up the screen. It used to be one, but now it's 3 or 4, moving up the screen always the same distance apart and it's each bar is getting bigger and more coulourfull!

Any ideas? I guess I'm going to need to call in a TV repair person but don't want to if they are going to charge me $100 to tell me I have to replace a "widget" which will cost $1000. If that's the case I'll buy a new TV.

Help!
Ecky

When I first got my TV, I was dismayed to find a vertical line near the middle of the screen. It was only on the DVD input. Turns out that by replacing the SVideo cable with a component cable, the problem went away. Don't know if it was in the color separation circuits, or just some noise phenomenon on the svideo cable.

[eckythump]

I'm using component connections, and it happens on my Cable HIDEF box and also my XBOX, so don't think it's wiring or the other components.

Thanks

[Floyd]

1. the equipment is several years old
2. the line moves up the screen, like the set is filling with water. Sometimes the line may look like a shadowed area(s).

These may be indications of a failing power supply in one of the devices. If it gets bad enough you may hear a hum or buzz as well. Assuming that you have a standard old-fashioned transformer-type power supply, the filtering capacitors may need replacement.

The transformer changes the AC voltage, then a bank of 4 rectifiers change the AC to DC, and then a large electrolytic capacitor smooths out the resulting voltage. If the cap dries out or otherwise loses its ability to store and release the rated amount of energy, the circuit will develope a waveform, resulting in pulses in the DC voltage. I think of it as a small amount of AC getting onto the DC, though that isn't exactly right. You can see this on an oscilloscope, or measure some of the AC at the cap with your meter set on the AC setting. Many power supplies use a multiple output transformer to develope several different voltages, each with its own filtering caps. You might be able to change the caps yourself.

If you have a newer swiching-type power supply, call the repair guy.

[passedpawn]

1. the equipment is several years old
2. the line moves up the screen, like the set is filling with water. Sometimes the line may look like a shadowed area(s).

These may be indications of a failing power supply in one of the devices. If it gets bad enough you may hear a hum or buzz as well. Assuming that you have a standard old-fashioned transformer-type power supply, the filtering capacitors may need replacement.

The transformer changes the AC voltage, then a bank of 4 rectifiers change the AC to DC, and then a large electrolytic capacitor smooths out the resulting voltage. If the cap dries out or otherwise loses its ability to store and release the rated amount of energy, the circuit will develope a waveform, resulting in pulses in the DC voltage. I think of it as a small amount of AC getting onto the DC, though that isn't exactly right. You can see this on an oscilloscope, or measure some of the AC at the cap with your meter set on the AC setting. Many power supplies use a multiple output transformer to develope several different voltages, each with its own filtering caps. You might be able to change the caps yourself.

If you have a newer swiching-type power supply, call the repair guy.

I had exactly this failure in a subwolfer. It blew at night. A big electrolytic cap dried out. Why they would put that thing next to a big heat sink is beyond me. I replaced the cap and the thing is back in commision.

[lifo]

Sounds like a ground loop. Make sure all your equipment and cable is grounded properly. Very common problem

[passedpawn]

I don't think it is a power supply problem or a ground loop problem. Could be, but nothing points directly to that. The blank lines indicate false HSyncs. These are the flags that cause a display to "carriage return" to the beginning of a new horizontal scan line. Since this problem is seen in equally spaced periods, sounds like there might be a noise issue in there... something burping occasionally and causing these errant synchs.

Do a google search, or post in the appropriate manuf. thread at hometheater.com. You might be surprised at how many folks have the same problem!