Mac Plus external Video Mod: TTL to VGA?

[BadGoldEagle]

Ok got it this time. Thanks!

I'll try to get in touch with NEC's tech support, I hope they'll be able to answer those questions. That projector isn't that old (circa 2005), and I didn't really search extensively. This is literally the first one that popped up when I googled 'multi sync projector', so there must be some other models out there.

Edit: But if it isn't NTSC or PAL, can the projector still hook up to the signal??

Edit 2: I am chatting with NEC's technical support as i'm writing this.

Edit 3: This model doesn't support that resolution, it seems to jump from 15.63 -> 31.47. Nothing in the twenties. They told me to check with their sales team. Will do that then!

 

[BadGoldEagle]

I think you're right Gorgonops, there's no such thing as a 22.15kHz projector.

So it seems there's only one option left (before I move on to another method), a scan converter like this one. This is the really expensive model, and I've seen the same one elsewhere around $120. I've sent them the specs, and they said they're gonna ask their engineering team if that'll work or not.

 

[NJRoadfan]

NEC's older projectors tended to work with 15khz RGB input. If that model has been tested for 15khz compatibility, its likely it'll sync with a 22.15khz signal too. Many arcade PCBs and the Sharp X68000 computer outputted 24khz (also close to EGA 640x350 mode), so its worth checking compatibility lists for those too. Many video scalers will support it as well (not that Startech things, you need something that handles RGB input).

 

[Bunsen]

I know there was a link floating around the forum to a guy who devised a way to drive the Mac's monitor from a VGA card under DOS (IE, the opposite of what's wanted here), I'm pretty sure I recall that link had some good notes about how the Mac's video signal differs from a proper TTL output.

That would be eviltim's MPXPlayer II

 

[BadGoldEagle]

Sorry for the lack of content for the past few weeks on this thread. It ain't dead yet!

I just totally forgot about it...

Yesterday I was thinking about Arcade machines, and it appears some use EGA. Now I wish I had read your post before that NJRoadfan... That's a great suggestion! I had a look online and there are quite a few EGA to VGA converters out there for vintage game cabinets.

For example:

http://www.ebay.com/itm/Arcade-Game-RGB-CGA-EGA-YUV-to-VGA-HD-Video-Converter-Board-HD9800-GBS8200-NEW-/162215306112?var=&hash=item25c4c92380:m:mszTVMEHjmnZoebaMOzUmXA

http://gonbes.gmc.globalmarket.com/products/details/ega-to-vga-converter-479349.html

According to the spec sheet (which is never wrong for cheap chinese products), it supports CGA/EGA 14.5kHz - 16.5kHz 23.5kHz - 25.5kHz 30.5kHz - 32.5kHz.

NOT 22.15 but still quite close (Δ=6%). I wonder that would work...

It would support the X68000 though!

From what I've read online, video scalers only convert the resolution, not the scan rate, right?

 

[NJRoadfan]

They convert the scan rate. The GBS-82xx converters tend to have poor video quality and have a nasty habit of needlessly applying de-interlacing to progressive scan signals. I wouldn't be surprised if it worked with a Mac's video output though, just don't expect pixel perfect quality.

 

[BadGoldEagle]

Thanks for the tip! And as you can see, I'm still at it.

Found this yesterday on ebay kleinanzeigen. And now it's mine!

   

   

So TTL it is then...

Since TTL is digital (unlike VGA), I should get a sharper image, right?

Of course I need to get a good 'converter' now, and I stumbled across these. This one and this one. They should work right?

Those things are pretty much identical. Apparently there are some fancy electronics in there allowing any signal (ranging from 12 to 40kHz) to be 'converted' to VGA 800x600. And they're available on ebay for about $200. Pricey, but if they promise what's on the box, those should do fine.

 

[Bolle]

Have seen this beeing offered for quite some time now.

Love how the design lets one use this thing in any of the compacts.

 

[BadGoldEagle]

Yeah. I wonder if it'll work on a Classic/Classic II... Probably not.

But according to the silkscreening on that PCB, it was made for an old ASK LCD Projector. Now all I need to do is find the right one... It must have been one of the really early ones given the 1988 copyright date. Ask is still around today, maybe they know which one this adapter was meant for?