# Help correcting overscan on HDTV



## Gnomo (Aug 22, 2006)

The other day I purchased a new Mac Mini and connected it to my Magnavox 26" HDTV (26MF605W/17) via the DVI port.

On initial boot, the menu bar, half of the dock, and a good portion of each side were off the screen.  I found a couple forums where people were asking about similar problems with different TVs which directed me to DisplayConfigX and SwitchResX.

I decided to download DisplayConfigX and started with the 720p HDTV setting and follow the procedure described on the website to correct the overscan.  I started by changing the vertical and horizontal front porches and was able to get the top and left sides where I wanted them.

The problem is that as I started changing the horizontal and vertical back porches, the bottom and right did not start moving as I expected.  Instead the top and left continued to move.

My experience doesn't seem to match what is described on DisplayConfigX website.  Can anyone explain this? or help me figure out which setting needs to be changed to get the results I'm looking for?

And before anyone asks, I do not get an "options" section in the displays preference pane, so I can't turn on/off the overscan checkbox.


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## Gnomo (Aug 26, 2006)

Since I haven't found anything worth while on Google and haven't gotten any suggestions yet, I started tinkering with the numbers in DisplayConfigX in an effort to better understand what each does.

Each Test started with the settings for 720p and adjusted from there.  Expected results are what the DisplayConfigX's website claims will happen.

Test 1: Decrease Vertical Active & Increase Vertical Back Porch
Expected: Top of the screen visible
Actual: Top of the screen visible, but moved bottom further off.

Test 2: Decrease Horizontal Active & Increase Horizontal Back Porch
Expected: Left of the Screen Visible
Actual: Left of the screen visible, but moved right further off.

Test 3: Decrease Horizontal Active & Increase Horizontal Front Porch
Expected: Right of the Screen Visible
Actual: Left of the screen visible, but moved right further off.

Test 4: Decrease Vertical Active & Increase Vertical Front Porch
Expected: Bottom of the screen visible
Actual: Top of the screen visible, but moved bottom further off.

Any help explaining why I'm getting the results I am or suggestions on what to try next would be greatly appreciated.


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## simbalala (Aug 26, 2006)

Check this thread:

http://www.macosxhints.com/article.php?story=20060319073027371


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