Here are the SwitchResX settings for the ZM-M220W that I alluded to in last
night's reply - these get it work via a Thunderbolt port using a DisplayPort to
VGA adapter cable on a new 27" iMac. I'm not sure if all these settings need
to be entered and even after entering the frequency specs the software could
not quite figure out the 1680x1050 resolution right. I thus configured it as a
Custom Resolution and got it to work.
Display Information Panel: (gleaned from manual)
V. freq 56 - 75 Hz
H. freq 31.50 - 80.00 kHz
Pixel Clock 28.32 - 135 MHz
Default Resolution 1680 x 1050 @ 60 Hz
Current Resolutions Panel:
Set to 1680 x 1050, 60 Hz (likely only available after setting custom
resolution in next panel)
Custom Resolutions:
Created a new one by clicking "+" button
Check the "Use simplified settings" button and selected CVT-RB from popup
menu
Set Active area as 1680 and 1050
Set Scan rate Vertical to 56.632 Hz
Selected Positive sync for Horizontal only.
Then saved and rebooted. Finally, it looks like you have to set the resolution
in the Displays panel for each use of the system (I use the Displays Menu bar
icon). And SwitchResX will set you back 14 ⬠(~$18) after a ten day demo
period.
Cheers,
Olve
======================
Final (auto-calculated) result was the following:
Pixel Clock 118.75 MHz
{Parameter Horiz Vert}
Active 1680 1050
Front Porch 48 3
Sync width 32 6
Back porch 80 21
Blanking 160 30 (not editable)
Total 1840 1080 (not editable)
Scan Rate 64.538 kHz 59.757 Hz
Selected Positive sync for Horizontal only
Final config became "1680 x 1050, 56.76 Hz"
