Fun with “Stuff”

I do apologise that I haven’t been updating as much as I could. There’s been personal things going on in the background that have slowed my output down.

Atari 2600

The replacement 6507 CPUs arrived and after hitting a dud, my second chip worked fine. This is why you always buy a couple.

I did hit an odd issue pretty much straight away. The system would work when out of the case, on the bench, but not with the case on, which was odd. It took me a while to work out what was going on. With the case on, slight pressure from the bevel was pushed on the power lead I’d made up. (It’s a standard 9V PSU 750mA, tip positive with a 3.5mm audio jack connector)

This is obviously before I put the case on. Combat!

I’d already rebuilt the socket on the board, but with the pressure from the case, it was enough to lever the tip away from the internal contact. Going through my parts bin, I was able to find an audio jack on an old tape drive cable for my Acorn Electron that had a much thinner outer shell section, and switching over, it worked fine with the case on.

After I got that working, I decided I needed to get rid of RF. It would be a pain to have to use RF with the television I wanted to connect to, so I looked around for a solution and found an excellent writeup on using S-Video with the unit.

The article here on NFG Games was simple, and easy to understand. The only complicating element was the difference between NTSC and PAL TIA chips, which I was able to discern with aid of a multimeter and the guide to the pinout differences I found here on Atari Age.

I designed up the board using a couple of different tools. By the time I was onto my third draft, I had reverted to using graph paper to finalise things and managed to get everything I wanted into a small footprint.

I ended up having to buy some bits and pieces from a local hardware store, most notably resistors, as it used some tuned values. Almost everything else I had on hand.

Once I had everything together, I assembled the board on some veroboard prototyping board.

It ended up to be quite a compact design.

The back, with many cuts to break the veroboard tracks up into electrical islands. I used my multimeter extensively through the process to make sure there were no shorts between islands.

After that, I spent the time finding all the appropriate places to tap for my various signals on the back of the board. Much checking went in to make sure I had the correct connection spot for everything.

Check. Check again. Check a third time.

Finally it was time, so I plugged in the cables and tested it and…

It works!

I had SVideo! This system now lives in my console wall and gets broken out for regular games of Space Invaders.

Sega MegaCD

Well, it just works with burned CDs, so media turned out to be a non issue. I need another PSU for this unit, and then it can join the 2600 in the console wall.

Saaaygah!

Omega MSX2

Finally got all my ducks in a row and ordered the acrylic to start cutting some cases. The Omega MSX2 now has a proper case!

There’s also most of a Microbee case in there, but I need to get a contrasting colour for the keyboard section.

It lives and the clear case and purple PCB looks stunning.

I did end up having to remove all my heatsinks from the chips as the keyboard ends up sitting too close to the top of the motherboard.

Really happy with the way this turned out.

TRS-80 CoCo2

I’m having some problems with this one. I seem to have a reasonably obscure revision of the motherboard, so I have had problems sourcing some chips.

I’ll get there in the end I’m sure. For now, I wait.

A New Pickup

Picked up this cutie from a fate worse than death. It worked as soon as I stuck batteries in it.

It even does a tinny rendition of the PacMan theme. Plays quite well too!

It needs some work as the screen surface has some cable burn but I’m hoping with the right polish, that I’ll be able to bring it back to a nicer finish.