Apple Laptop Presentation

[BPoese]

I'm not sure if this is the correct location for this - so please move it if it's not. We had a conference at our church this past week. One of the presenters had an Apple laptop (Powerbook, I think). I had the video setup for the presenters to hook up their laptops to a VGA cable. The cable ran back to the sound booth to a video switcher and then to two large projectors and one small projector. I knew before hand that there was going to be an Apple laptop, so I went out and bought a mini-DVI to VGA convertor cable ($20) so he could connect to the VGA cable.

When he connected to the cable his images had moving waves going up and down the image. On the big projection screens, it did not look too bad but you did notice it. On the smaller (cheaper) projector it looked really bad.

Did I buy a cheap convertor and that was the problem or what else should I have done?

Thanks
Bruce

[jksbc]

I'm curious, did he have his laptop plugged in? That sounds like video hum caused by grounding issues.

[BPoese]

Yes the laptop was plugged into a grounded outlet. However I do not remember if the laptop had a 3 prong plug or not.

[sempei13]

If it was a powerbook, there were two styles of power adapters that apple sold (and numerous 3rd party versions). One had two prong and one had three, so it's possible he had a two prong. Running unplugged might have fixed this.

Paul