Macbook trackpads and Epson Powerlite 83+

Question

Level 1

5 points

Macbook trackpads and Epson Powerlite 83+

we have found a problem with our new MacBooks(MC516LL/A) and Epson Powerlite 83+ projectors.
when we connect the projector with the Mini DisplayPort to VGA dongle(MB572Z/A) the trackpad gets Jumpy and unusable.

what we have tried
external mouse works fine
Infocus LP640 projector Works fine
Acer VGA monitor works fine
Replicatable on all MacBooks we tried

any thoughts

Posted on Feb 4, 2011 11:23 AM

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Answer 1

BSteely

Level 5

7,643 points

Feb 7, 2011 6:04 AM in response to Sam Cornn

Is the projector plugged into the wall with a two prong adapter or a three prong (grounded) adapter?

The trackpad works on the principal of projected capacitance. If the reference potential of the notebook is way off from that of the person touching the trackpad, what you describe can happen. So check the cabling and grounding. It seems the projector isn't wired correctly to the utility and/or ground.

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Answer 2

Sam Cornn Author

Level 1

5 points

Feb 7, 2011 6:22 AM in response to BSteely

@BSteely I think you may have something there.
this projector only has a 2 prong plug i.e. http://www.hellosurge.com/images/l/201005/12735712130.jpg

but the other infocus & VGA monitor I tested have a grounded plug.

If the Macbook was grounded would it make a difference? Not that you can evan with the 3 prong cable it only has 2 prongs that connect to the brick.

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Answer 3

BSteely

Level 5

7,643 points

Feb 7, 2011 7:55 AM in response to Sam Cornn

Grounding the MacBook would be a good test. The power cord on the AC adapter has three prongs.

Message was edited by: BSteely

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Answer 4

Sam Cornn Author

Level 1

5 points

Feb 10, 2011 8:17 AM in response to BSteely

Grounding the projector fixed it. Now we just need to make power cord dongles that have a ground cable to go to the ground screw on the RS232 connector on the projectors.
Thanks for the help!

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