Display output to older monitors

By Anonymous (not verified) at Wed, Mar 22 2006 12:17pm |

General Discussion

I have noticed that my newer Macs (including MacBook Pro and Dual G5 PowerMac) refuse to send display output to some older display devices (the one I really want to get working is an Epson PowerLite 710c projector).

If I connect the Mac DVI output to these devices (using an Apple DVI to VGA converter, although I've tried 2 other converters with the same result), the display will flash once, showing the Mac desktop, but then return to "no signal". Selecting "Detect Displays" in system preferences causes another identical flash, and still no signal. The Mac still reports only the primary display in the display list.

I can drive these displays just fine from my old iBook G3.

Interestingly enough, I can also "trick" my MacBook into driving these displays. If I connect the macbook (via DVI to VGA adapter) to a newer monitor (Dell 2100FP), and "Detect Displays" I get a second desktop on the Dell monitor. Now if I switch the VGA cable from the Dell to the Epson projector, I get a working second display on the projector. I can then change resolution and color profiles in Display Preferences, and everything works fine. However, 1) The MacBook still lists the second display as "Dell 2100FP", and 2) If I ever choose "detect displays" again the projector flashes and goes blank.

AFAICT, the MacBook (and PowerMac) must be requiring some sort of active feedback from the monitor that my old projector doesn't provide. I've been told some new PCs have this property also, and maybe it is a function of the video card. In any case, I would like to find a workaround that lets me use my projector.

Ideally, there should be a command line idiom that causes the machine to just send a display, with some resolution and frequency, to the external DVI port, whether it "thinks this is a good idea" or not. If anyone knows how to do such a thing, please let me know. (I am Graham Cummins, at gic@cns.montana.edu)

Thanks.

Thu, 2006-03-23 10:50 — joel

DisplayConfigX

I have'nt used this application myself, but I hear great things about it. It might allow you to force your machines to send a signal to the projector.

http://www.3dexpress.de/index.html

Thu, 2006-03-23 11:49 — Graham Cummins (not verified)

DisplayConfig

Thanks for the suggestion.

Sadly, this program doesn't help. It allows you to set up the display parameters for the displays that were in the system display list when the program started. Since the problem is in getting the MacBook to detect the projector in the first place (and thus add it to the list of displays, this isn't enough.

Really what I need is a way to get the externl DVI port added to the list of active displays, even when OSX doesn't "think" there is a monitor attached to it. Once I have a second display entry to work with at all, the OSX options for setting resolution and frequency are quite adequate.

Thu, 2006-03-23 11:57 — joel