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Old Macs and VGA Monitors

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wesleyfurr

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Jul 16, 2009
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Virginia, USA
Quick question...are there any old Macs (or video boards for them) that will not work with a modern VGA (thinking mainly LCD) monitor? I've got a battery-leak-damaged IIcx that I have a replacement motherboard for...I do know it has a DB-15 connector on the video card...just wondering what the likelihood is it will work with an adapter on an LCD monitor. Would be good to know about other old Mac's as well for future reference.

Thanks,

Wesley
 
Passive Mac II video to VGA adapters will "work" but with the limitation that you will be stuck in 640x480 @ 60 Hz because the Macintosh won't be able to properly detect the monitor.

If you want to be able to use different resolutions, you'll need one of the more advanced adapters with dip switches to fake the Macintosh into thinking a specific display is attached.

The advanced adapters look something like this:

B8801817662.jpg
 
I've heard that there are one or two Macs that won't work with a VGA adapter. Not sure which ones and if it's true at all. All Macs I own work fine with VGA.
 
I think an LC 1 with no extra VRAM only does under 640x480 resolution so a VGA adapter and any LCD will not work. There are plenty of add-on cards that need sync on green to work or are fixed frequency and might not work with an LCD panel.
 
Well...my reason for asking is I have a IIcx that got its board ruined by a leaking battery. Just got a replacement from someone for the cost of shipping, but it was of unknown condition. Stuck it in and fired it up, but am not getting any video or chime. Sometimes it acts goofy trying to power on - only staying powered on if you hold in the power button on the back. Tried it both with its video card and one I pulled out of a IIci. Does this sound like a motherboard capacitor issue? Maybe something else?

Thanks,

Wesley
 
Besides the sense pins, the other issues with Macs are the sync lines. Apple didn't standardize on separate horizontal and vertical sync output until later. Early ports could use composite sync or sync-on-green. Adapters like the one pictured above have internal sync splitters to handle that and output proper H+V sync for VGA monitors that require it. LCDs may also have issues with refresh rates too, Macs generally used 67Hz for 640x480 video instead of 60Hz.
 
Thanks for the info. I've used my monitor with LC machines just fine...but they probably are later enough to be more standard. I'll go with my gut that says capacitors need replacing...should at least here the startup chime I would think...

Thanks,

Wesley

njroadfan said:
Besides the sense pins, the other issues with Macs are the sync lines. Apple didn't standardize on separate horizontal and vertical sync output until later. Early ports could use composite sync or sync-on-green. Adapters like the one pictured above have internal sync splitters to handle that and output proper H+V sync for VGA monitors that require it. LCDs may also have issues with refresh rates too, Macs generally used 67Hz for 640x480 video instead of 60Hz.
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