A Question about mac to vga adapters.

[Bagger]

I got an LCD projection panel (sits on top of an overhead projector) and it has a 15-pin female mac connector on it. I want to hook up my PC to this display. I see alot of mac to vga adapters but they all state that the adapter will "allow you to hook up your mac to your vga monitor". What I really want to do is hook my PC up to my "mac monitor". They have this adapter at Newegg which shows the same kind of hookup previously mentioned. But then I saw this item on ebay that states "Use your Macintosh monitor with your PC.". Now the item in the first link has all kinds of dip switches to set various resolutions but the second item doesn't appaer to have any dip switches at all. Anyone here have enough knowledge about this kinda thing to set me straight?

Thanks

 

[glugglug]

12 of the 15 pins on either connector are the same.

For the remaining 3, the mac has always used them as a monitor size code, each one can be 0V, 5V, or floating for 27 possible codes to indicate different monitor sizes. The old mac monitors were not multi-sync, so this code determines what resolution the mac's video will output. (So the dip switches would be to pick a monitor size to tell the mac. There are a few codes you can put them on that will tell a newer mac you have a multisync monitor so it gives you resolution choices after boot).

On a PC those 3 pins are used by PnP OSes and PnP monitors for a serial connection where the monitor gives the computer its PnP ID and other specs. If they are not connected windows will just see the monitor as standard VGA and the "Hide modes that this monitor can't display" checkbox in the display control panel just won't really do anything.

I don't know if the projector would be non-multisync like an old mac monitor, it should list sync frequency or ranges in the spec somewhere.... If it is, you will have to set up your video card to output at the right frequency for it with powerstrip or something. Some of the modes are not standard on PCs, for example the 14" displays are 640x480@66Hz and the 17" are 832x624@75Hz.

 

[Bagger]

That's very interesting information.. and maybe if I was more familiar with all of that then that would've helped answer my question The LCD panel is set at 640x480 native resolution, most likely needing to run at 60hz. Would both connectors do the job? Do I need to have the dip switches?

 

[glugglug]

If its 640x480 its probably 66Hz.

The 2nd adapter is what you want but you need to add that mode to windows with powerstrip or other util.

 

[Bagger]

OK I took a look around Powerstrip, and I see an Advanced Timing Options section...

It lists a Horizontal gemoetry section, and a Vertical geometry setting...
Under Horizontal it shows a default Scan rate of 60.023 kHz
Under Vertical it shows a default Refresh rate of 75.029 Hz

I'm assuming I just want to change the Vertical Refresh rate to 66 Hz then?

I ordered that second adapter off of Ebay so hopefully I'll get it before the end of this coming week. Then I can test out this display to see how well it works.

 

[glugglug]

ya when you change the vertical refresh and tab out of it, the horizontal should change automatically by the same ratio.

One thing though:

75Hz refresh with 60kHz horizontal doesn't sound like a 640x480 ratio to me more like 1024x768 maybe.

Have to change to 640x480 first.