Hacking a VGA port onto the SE mobo

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doug-doug the mighty's picture
Joined: Apr 14 2004
Posts: 1355

The plan here is to replace the stock CRT in my new SE with a 9" or 10" LCD. I need to get the video signal out and am unsure of the pinouts on the primary artery that connects the mobo to the analog(?) board. I will take care of everything else, and make this work, but I need to know how to shunt a VGA connector off of the mobo.



--DDTM ('Fritter Critter' since Apr 26 2004 - 18:16)

'If it ain't broke, take it apart anyways. If you can't take it apart, break it so that you can fix it.'

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Jon's picture
Joined: Dec 20 2003
Posts: 2804
The SE doesn't use VGA signal

The SE doesn't use VGA signalling. FWI Seem To Recall, it should be something like an old 15Khz signal of some sort. Maybe an old multi-sync or other sub-VGA capable monitor might be able to sync to it. Otherwise you'll need what in the old Amiga world were "scan-doublers". They took that 15.xKHz and doubled the frequency to 31.5KHz to use a basic VGA screen. I never had a doubler, so I just bought an NEC MultiSync 3D for my old A2000. It could do some low frequency video modes.


I am not in this world to live up to other people's expectations, nor do I feel that the world must live up to mine. - Fritz Perls

Eudimorphodon's picture
Joined: Dec 21 2003
Posts: 1203
Re: The SE doesn't use VGA signal

Jon wrote:

FWI Seem To Recall, it should be something like an old 15Khz signal of some sort.

I don't recall the exact number, but it's actually around 23Khz. Roughly the same as the old IBM "EGA" standard.

They used to sell adapters so tap out the signal so it could be displayed on suitable fixed or multisync *digital* monitors:


They even sold a matching 12" monitor.


Note that VGA is *analog*, although it would be fairly trivial to convert the output to something that works, considering there's only black and white, no greys. However, also note the sync rate is well below what most modern multisync monitors will sync with, and that's going to include most (every?) VGA->LCD controller board.

Good luck.

DrBunsen's picture
Joined: Dec 20 2003
Posts: 946
I wonder... The resolution

I wonder...

The resolution is what, 512 x three hundred-something? I wonder if there are any monochrome graphic LCDs that would be fast enough. You'd have to design an interface, perhaps with a PIC or Scenix µcontroller to do the conversions from analog to serial digital. 23kHz sounds doable - the PIC 18s run at 40MHz.

(By graphic LCD I mean the small panels that electronics manufacturers and hobbyists use as device interfaces, not a VGA/Powerbook/other holy grail LCD)

/me pictures a 5" mini Mac Plus


Damn the Torx screws, full speed ahead!
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