I am having a problem with my TV. It seems that whenever it is in the VIDEO mode there are black vertical lines across the TV. They are worse on the right hand side. It has been doing this for a few years, but it has gotten worse recently. It is hard to describe, but they are thick, translucent lines. Any ideas on how to get rid of them?

Buy a Japanese TV.

I agree. Zenith isn't that great. The one I have has some averse reactions to video game consoles. Hated Playstation, and somewhat dislikes Gamecube.

Other than that, it hasn't had the reactions you've described. And this is a pretty old one.

Too bad most TV's aren't as hackable as the empeg.

Although my Mitsubishi high-def comes pretty close.

Sounds like some component is slowly dying and it's value is changing over time. Most probably a electrolytic cap somewhere is drying out. I wouldn't try and repair it yourself unless you're experienced in electronics and the hazards present in a TV.

- Trevor

It's got to be a problem with a component inside the TV (most likely a transformer, in my uninformed opinion). Your recourses are likely to be to take it to the TV repairman or to buy a new TV. Given that it's a 25" TV, buying a new one is probably the price performer here. It might be worth it to get a quote from a reputable repairman, though.

I used to have some tall speakers next to the TV which would sometimes turn the screen different colors. Would that have anything to do with it?

if it were the transformer, why would it only do it when it is in the video mode? Is it because the higher resolution?

Nah. They'd just mess up your colour because of the magnetic field as you've seen. Since it only happens when you're using the video input mode of the TV it isn't that since it would also screw up your normal reception.

- Trevor

Many modern televisions use digital signal processing circuitry to improve the picture of certain inputs. Do the vertical lines look digital? For instance, do they have sharp edges as if they were rectangles drawn in photoshop? If so, you'll know the most likely source of the problem...

no....they are translucent...it almost looks like the contrast is darker where the lines are, but you can still see the picture.

If they are hard-edged pixels and always in the same place on the screen, it could still be a DSP or video-board problem, even if they are translucent. They don't have to be a solid color in order for it to be a digital problem. If they're fuzzy-edged and/or they move around the screen, then it's an analog problem.

it is an old TV though....it is from around 1992

It seems that whenever it is in the VIDEO mode there are black vertical lines across the TV. They are worse on the right hand side. <snip> It is hard to describe, but they are thick, translucent lines

You seem to be contradicting yourself a bit here but translucent (with a darkening effect) is what I think you are are getting.

On that assumption, it's probably a phenomena called Ringing. What may be happening is the AV signal is being reflected up & down the AV cable and contributing to the picture each time on each reflection cycle, it will eventually diminish to the point where it doesn't show up on the screen. I.e. it's less noticeable further from the edge of the screen.

This could be caused by a fault but it's probably an impedance mismatch between the equipment or a poor or incompatible cable.

That was back before they invented digital.

Calvin

Sorry. I didn't follow that part about it being only in one mode.

It sounds like signal reflections, probably caused by incorrect line termination. A composite video signal should be terminated at both ends by a 75ohm impedance. Some cheap TVs seem to have issues with correct termination somewhere in the signal path, in this case most likely in the signal multiplexer which is used to switch between the video in and the internally generated video.

If the signal isn't correctly terminated, sharp changes in level (black to white transitions, sync pulses, etc) which have a very high frequency component and lots of harmonics will reflect from the driven end of the input and bounce up and down the cabling until the energy is dissipated. It's also called 'Ringing'. I would guess that in this case the guts of the thing are pretty cheaply made (it IS a Zenith!), and the input amplifier simply isn't very high quality. Possibly the termination resistance, whatever it is, is changing value as it ages, or it could be reflections caused by bad PCB layout in the imput stage. In either case, there probably isn't a lot you can do about it.

That said, have you tried a new video cable? It's barely possible that there is a problem with the impedance of the connectors on your current one, or something of that nature.

pca