Can you wire VGA out from a Mac Classic's motherboard?

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Joined: Aug 14 2010
Posts: 7

Hey guys,

I'm undertaking a project to make a laptop out of the guts from a Macintosh Classic (or Classic II, SE, SE/30, Plus) computer. The thing that this project being possible hinges on is the possibility to remove the built in CRT screen, and get the video output straight off the Mac's boards.

Short version of the question I'm asking would be: "Can you wire VGA out from a Mac Classic's motherboard?"''

Any input would be much appreciated,

Thanks! Smile

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eeun's picture
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Joined: Dec 19 2003
Posts: 1891
The short answer

The short answer is "no".

The toaster Mac logic boards don't generate a VGA signal without external circuitry. There were a few add-on boards that did this, but they are now very rare and carry a premium price.

The pizza-box form factor Macs (LC, peforma 475, Quadra 605, etc.) have a similarly small logic board, but do output colour VGA.

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Joined: Aug 14 2010
Posts: 7
I was afraid that that would

I was afraid that that would be the answer.. Do you (or anyone else) know what format the video signals are passed from the logic board to the built in CRT? I could possibly make an adapter myself if it's something not too insane Smile

The big thing about this project is my love for the Mac SE I had when growing up, so wanted to turn one of those (or one of the ones that look the same) into a laptop. Using a pizza-box form factor Mac just wouldn't be the same (although it may be my only option)

Thanks for your reply Laughing out loud

Eudimorphodon's picture
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Joined: Dec 21 2003
Posts: 1204
What qualifies as "insane"?

The Mac monitor is essentially *completely* different from VGA in terms of signal levels and scan rates. Unless your monitor is able to accept the oddball scan rates from the Macintosh:

Horizontal scan rate: 22.3KHZ
Pixel Clock: 15.667 Mhz

(About the closest PC standard to this was EGA) you'll have to construct a scan converter to drive a VGA monitor. Building such a thing would be a fairly involved project. (A simple "scan doubler" would still result in a very non-standard video signal so you'd be looking at a full-fledged framebuffer-equipped model.)

Honestly it'd probably be more feasible to start with a bare TTL LCD panel and drive it directly. You might find a suitable one surplus. (640x400 monochrome LCD panels were fairly common. You'd have to look at the data sheet carefully to see if you could make the timing work at all. Many older LCDs were divided into multiple chunks which had to be refreshed simultaneously, which would also require either a conversion framebuffer or modifying the video sections of the Mac motherboard. (Decidedly non-trivial.)

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Joined: Aug 14 2010
Posts: 7
Wow.. I didn't realise what I

Wow.. I didn't realise what I was getting myself into!

I think, for my sanity, I'd be better off getting a pizza-box form factor mac that already has VGA out

Thanks very much for your input guys!

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Joined: Aug 14 2010
Posts: 7
Wow.. I didn't realise what I

Sorry, my comp made it post twice...