Apple Mini-DVI -> Video Adapter Ate My @#$%s....

[kalisphoenix]

Okay, I'm having a problem with this little gem (the S-Video/Composite output device). The problem is that the picture on the TV is distorted. Mostly the color is okay, but there's a moving band where it looks bleached. Also, there are two black bumps (one on each side, assymetric in size and location) that move down the sides of the screen. The image rolls occasionally (every couple seconds).

The adapter is detected fine (as a TV, and not as a monitor). I can adjust resolution and mirror/extend desktop fine. I've changed the miscellaneous settings ("Best for Video" and "Overscan"), the refresh rates, colors, resolutions, all that crap.

I know the TV works fine, because I use it for everything and I've used a Mini-DVI -> Video adapter with it before -- just not this one, and not from this computer (it was from an iBook G4).

I know the cables aren't the problem, since I've swapped them around like mad.

The port/card shouldn't be the problem, because I have a Mini-DVI -> VGA out that I use for a second monitor, and that works fine.

Any answers? Is this definitely hardware, or perhaps a software conflict, iB0rk with an update, or ? Help? Anyone?

 

[someguy]

I'm no expert, but it sounds like low refresh setting or intereference with a magnetic device or nearby monitor or TV.

 

[kalisphoenix]

I don't think it is. I turned off my second monitor while trying to get this to work. I moved the speaker that is closest to the cable (it's tiny anyway). Hmmph. I think it's just Apple hatin' on me again :-(

 

[kalisphoenix]

Update: I purchased another adapter. Sure enough, that's not the problem.

I reinstalled OS X. That's not the problem.

I looked at getting an appointment with a Genius, but the Concierge doesn't seem to want to help me there. So it looks like this problem's just going to sit for a while. Bastards.

 

[Eraserhead]

Okay, I'm having a problem with this little gem (the S-Video/Composite output device). The problem is that the picture on the TV is distorted. Mostly the color is okay, but there's a moving band where it looks bleached. Also, there are two black bumps (one on each side, assymetric in size and location) that move down the sides of the screen. The image rolls occasionally (every couple seconds).

The adapter is detected fine (as a TV, and not as a monitor). I can adjust resolution and mirror/extend desktop fine. I've changed the miscellaneous settings ("Best for Video" and "Overscan"), the refresh rates, colors, resolutions, all that crap.

I know the TV works fine, because I use it for everything and I've used a Mini-DVI -> Video adapter with it before -- just not this one, and not from this computer (it was from an iBook G4).

With an iBook wouldn't it be a mini vga connector? Have you tried it with a different TV?

It could also be the Composite/SVideo Video cable, I had a cheap crap one which caused artefacts similar to the ones you are describing to appear on the screen sometimes.

 

[kalisphoenix]

With an iBook wouldn't it be a mini vga connector?

Indeed it was... but I wouldn't expect that an iBook's mini-VGA -> Video adapter would require a certain specification of television that an iMac's mini-DVI -> Video adapter would not be able to handle, or vice versa. It's a 20" TV, it has composite video in, and it's only a couple years old. So I'd expect it to work.

Have you tried it with a different TV?

I don't have any other TVs, live hundreds of miles from my family, we're broke, and we're new in town and don't really know anyone that we can just drop in on.

It could also be the Composite/SVideo Video cable, I had a cheap crap one which caused artefacts similar to the ones you are describing to appear on the screen sometimes.

If you mean the Apple adapter, I've bought another one which doesn't work either. If you mean the actual RCA or whatever cable, I suppose that's possible but I've tried a couple different ones and I don't think it's possible that all of them are screwed up. I suppose it might be solved by buying a well-shielded high-quality cable, but at this point it sounds like just another $30 on top of the $40 I've paid for the adapters. :-/

Thanks for your help, though I can't believe that I would be the only person with this problem, and it seems like people are ignoring me :-(

 

[Eraserhead]

If you mean the actual RCA or whatever cable, I suppose that's possible but I've tried a couple different ones and I don't think it's possible that all of them are screwed up.

Yeah that's what I was thinking... If you play with the RCA cable does the interference move around the screen? I assume the interference doesn't move if the cable's stays where they are. Try to move the mini DVI adapter as well and see if that is affecting the interference either.

Note that the RCA/S-Video cables I have had no problems with cost about £2-£3 each, the cheap cable came free with an old PC and had been sitting around for several years.

Oh and one more thing, try blowing hard into the ends of all of the cables and into the relevant ports on your TV/Mac to remove any dust in them, as that could be causing problems.

If neither appear to be causing the problem, the problem is probably your Mac's Mini DVI port itself.

 

[Beachcomber]

try disconnecting your cable tv connection, could be a ground loop issue.

 

[gatortpk]

try disconnecting your cable tv connection, could be a ground loop issue.

It sounds exactly like a ground loop, that bleached band is called a "hum bar". Though this usually happens with the TV being grounded to the house's eletrical system (earth) and the CATV grounded not so well, the two grounds are at a different potential causing a current through the video cable.

But in your case its the analog video cable from your computer and your TV having a good ground. Ever notice that strange "vibrating" sensation when you run your finger along the aluminum of a mac. That's current at 60 Hz (or 50 Hz in Europe) running through your finger (and body). The computer isn't grounded (very well) and causing the distortion. I'm no expert, but that's what it sounds like, though I've never seen it.

Try plugging the computer and TV to the same surge protector, or at least the same outlet. Maybe try putting the computer ON your TV (set it on top or touch the aluminum to the TV (not the fragile LCD glass)), see if that changes the distortion, if it does, then you have and idea of what your problem is and can go from there. Again I'm no expert, but I would think that the computers video would be somewhat isolated with something similar to isolation transformers. May be that's why I've never seen this issue.