12" Monochrome on modern Mac

[Dandu]

Hi, 

I have a little problem. I have found a 12" monochrome monitor (High Res) and i will try to connect the display to a modern Mac. And it will not work : https://www.journaldulapin.com/2018/08/17/crt-apple/ 

The display is working with an old Mac LC, with a Power Mac G3 (beige), but not with a modern computer. It's a fixed definition model (640x480@66) but when i try with DA15 to DB15 adapter, i can have an image, but not the synchronisation. This page say the display use a composite sync, but even with an adapter who can use (i presume) the composite sync, it will not work.

Can you help me ? Is there a special adapter for that ?

 

[Trash80toHP_Mini]

Older Macs supported the refresh rates of legacy displays, but modern computers dropped it at some point. The link you posted appears to spec a PowerMac G3, so it works. Any newer Mac or VidCard that doesn't have a 66.7Hz output for that legacy fixed frequency displays won't work sync up. Passive adaptation is a one way street, legacy mac resolution outputs will usually work as inputs for a multisync display, but not in the opposite direction to a legacy display.

 

[Dandu]

Actually, i can force 640x480 @ 66 with SwitchresX, it's not the problem. The problem is the sync : i see the image "scrolling" when i use the correct timing.

 

[Trash80toHP_Mini]

Is sync on the green line?

 

[Cory5412]

You might try 67Hz instead of 66 or 66.7, but I've never seen any examples of this working.

It is somewhere in the late Power Mac G4 era that support for the old fixed-sync displays stopped. (I actually should test this with my TiBook@1GHz and my QS'02 at some point.)

I don't believe SoG is the issue, to my recollection only the portrait display and maybe the 21-inch Macintosh Color Display used that sync type.