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video noise, xr system

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EclecticBubbavideo noise, xr system
by on Oct 16, 2006 at 10:52:40 pm

Trying to troubleshoot a problem that's been developing and has reached critical mass... I'm seeing a fair bit of "noise" in my video signal - most easily visible in a black or very dark video signal. on a Waveform, (expanded) you can see the black line with goosebumps, and at its worst, what appears to be a tiny ground humm slowly rumbles through.

I've isolated all equipment, and isolated AC supplies and cables (video and audio as well) ... I've swapped with a friend's BOB. Thinking it must be a leaky cap on the media 100 board, I paid for a re-furb board after reviewing options w/ tech support. I was surprised when that did not cure the problem.

I've got a G4 Mirror door model, (1.42) with a Radeon 9000 Card, an ATTO card running some old SCSI's, and some Glyph firewire drives. I'm running 10.4.7 os, and 8.2.3 Media 100. This shows up even when playing a media 100 black clip, or an imported photoshop graphic or color. It does NOT appear to show noise in anything from the DV input output side. It appears to be analog input / output only. (perhaps this is due to the setup difference?... though it's bad enough, I think I would see something.)

M100 Tech support and common sense says it's the "environment" and I'm wondering if it's in the G4....

I'm curious if anyone thinks it could be the Radeon card. Could the video card "bleed" ground or other problems over to the media100 board? I don't have one handly to swap, and the G4 has only a few recommended cards to use -- and they're getting hard to find. Or is it more likely the mother board?

The signal is deteriorating enough as to be unusable.

Here's another interesting quirk: I bought a couple "on sale" LCD monitors (doublesight) and the system wouldn't shut down when I connected them. I found an obscure Apple tech bulletin that said some of the cheaper (non-apple) lcd's would restart the machines unless completely disconnected from power. I do that now, and no problem. (This noise problem preceded this new set of monitors, though.) I've also noted that if I disconnect the monitors while playing test timeline, sometimes it makes a significant difference in the noise, BUT NOT ALWAYS. more confused than ever? I thought so.

anyone else ever had a problem like this? suggestions? (I'll probably end up ordering a refurb video card somewhere... but am worried if that's not it...)


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Arthur DentRe: video noise, xr system
by on Oct 17, 2006 at 5:20:24 pm

could be a dirty power system. I'm not an electrician by any means, but I've heard that electrical supplies can introduce noise into eletronic systems. Is ALL your equipment on the same electrical circuit, If maybe not try to get everying that connects to your Mac on the same circuit (Decks, monitors, mixers etc) so that they are on the same eletrical cycle?

Maybe a dying power supply unit in your G4, have you tried another G4 (if you have access to one?)


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EclecticBubbaRe: video noise, xr system
by on Oct 17, 2006 at 8:02:33 pm

I've got everything on the same power source - it's what I first suspected. I've thought about the power supply - and I may end up replacing it as a matter of course. I would have thought that that a bad PS would show up on all the video i/o's... but I know they can be as flaky as anything else.
I think I'll try and get a video card on ebay, and then try the PS if that doesn't work.

I don't have access to another G4, or at least this model... (i've heard the mirror door model is flaky.... )


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