Some old school mods!!!

[Fred1212]

Some people hated the compact Mac obviously. These are 512k boards with a homebrew VGA adaptor in an old PC type case. I haven't tested them yet. Pull apart and clean/inspect then see what happens.

 

[68kPlus]

That's really cool! I remember seeing these on eBay I think. If you can get them going do post it on here! Would love to see them in action.

 

[cheesestraws]

You don't see many of those in the wild! I think those used to be called "cat macs", for "catalogue", because you ordered the bits from catalogues then put them together yourself. There's recipes for this kind of thing in the book Build your own Mac and save a bundle (or words to that effect). That book is oddly useful these days because it tells you things like what connectors are used in the early Macs, saves a lot of staring at datasheets..,

That graphics output will not be VGA, though - while I can't see enough on the more complex board to see what it's doing properly, there's no way two 74 series logic chips is enough to retime the Mac's video signal to VGA standards. So don't be disheartened if you plug it in and you don't get video - you may well need a forgiving scaler or rgb2hdmi or something on the output.

 

[Fred1212]

What do you think the video socket and board is for?

 

[Fred1212]

On further inspection looks like a CGA socket. @68kPlus your correct came from Epay and I probably paid way too much but was intrigued to see what it was!

 

[68kPlus]

On further inspection looks like a CGA socket. @68kPlus your correct came from Epay and I probably paid way too much but was intrigued to see what it was!

Nice. I was intrigued by them, that's for sure.

 

[Byrd]

I saw the auction too but forgot about it; glad you scored it Fred! The video out is probably Monochrome TTL (aka Hercules), not CGA, these monitors are really hard to find.

 

[Fred1212]

Yes Your right need to do some research on TTL to VGA? or some such

 

[cheesestraws]

Yes, it'll be monochrome TTL. The timings and resolution will be weird. If you look in Build your own Mac and save a bundle that gives examples of some screens that work with it, IIRC: or, again,use an rgb2hdmi or similar.

 

[Fred1212]

Thanks found Build your own MAC very interesting

 

[cheesestraws]

yeah it's a cool book - has details that are still useful about what connectors are used for various things

 

[Byrd]

Yes Your right need to do some research on TTL to VGA? or some such

This device might do what you need - a Raspberry Pi Pico to TTL/CGA/EGA converter, was cheap and used to be sold as a complete kit but maybe not now, still looks impressive.

MDA/CGA/EGA to VGA Converter Released! - Page 12 \ VOGONS

www.vogons.org

Another product here but pretty expensive

RGBtoHDMI - 6-bit TTL Edition - TexElec

The RGBtoHDMI is an excellent open project created by Hoglet67 (David Banks) and IanB (Ian Bradbury). The purpose of the RGBtoHDMI is to convert many different TTL and analog video signals from vintage systems to a modern HDMI or DVI compatible output. It uses a Raspberry Pi Zero along with a...

texelec.com

 

[davewongillies]

Raspberry Pi Pico to TTL/CGA/EGA converter, was cheap and used to be sold as a complete kit but maybe not now, still looks impressive.

It can be purchased here

RGBTOHDMI for IBM PC MDA, CGA, EGA,Olivetti Prodest PC1and Commodore C128 - Complete With Pi Fitted

New Batch with support for a IBM PC MDA, CGA, EGA (2, 4 or 6 bit TTL) / Olivetti Prodest PC1 (4 bit RGBI TTL) / Commodore 128 80 column (4 bit RGBI TTL) Latest version with more buffering and a DB9 connector directly on the unit allowing direct connection of hardware. This comes with a...

www.sellmyretro.com

 

[Fred1212]

Hey thanks for the info fellas

 

[Fred1212]

Ordered the rgbtohdmi see what happens

 

[joshc]

Those are a nice find. I’ve never seen any for sale.

What are your plans, once you have video output?

It looks like some better cable management wouldn’t go amiss, as it currently looks like the engine bay of an old car. But in a way, it’s nice to keep them as they are…

 

[Fred1212]

I plan to get at least one working and then tidy it up as a restored example

 

[joshc]

You may or may not end up having to repair or replace the power supply they used. A Mac logicboard is easy to power, and a modern replacement (e.g a Seasonic or MeanWell) unit is going to be more efficient and safer than the old unit. The ‘heat sink is live’ warning sticker there is … well, I’m glad the warning sticker *is* there, but it still leaves me feeling a bit ‘eh’ that it’s live at all.

 

[cheesestraws]

The ‘heat sink is live’ warning sticker there is … well, I’m glad the warning sticker *is* there, but it still leaves me feeling a bit ‘eh’ that it’s live at all

This isn't at all uncommon. One of the heatsinks on the normal plus AB is live. Someone did once explain to me why - there is a good reason for it - but I cannot for the life of me remember why. It's still the case in quite a lot of modern PSUs. This kind of thing is why you shouldn't poke PSUs unless you're very sure you know what's going on.

 

[joshc]

This isn't at all uncommon. One of the heatsinks on the normal plus AB is live. Someone did once explain to me why - there is a good reason for it - but I cannot for the life of me remember why. It's still the case in quite a lot of modern PSUs. This kind of thing is why you shouldn't poke PSUs unless you're very sure you know what's going on.

I did know about the Plus analog board having a live heat sink but I wasn’t aware it’s still the case in modern PSUs too.

In any case, I guess OP should assume the worst when it comes to that power supply - I get the feeling it hasn’t been powered up for a long time.

I guess…Turn it on at a distance with a long wooden stick right next to the plug socket so you can kill power if apocalypse happens?