Atari Jr - Sorry I can't think of a fun title.... - Part 1

My 'bio' over in that corner over there says that I'm an Amiga Nut. This is true, but it doesn't necessarily mean that I was a Commodore fan-boy. Not me. My computer life started with a ZX Spectrum + in about 1984, then progressed to the SAM Coupe (now ultra rare, very expensive and we threw it away in about 2004 - don't ask...) and then the Amiga before succumbing to the PC.

But then I realised that, even with a couple of diversions into consoles like the ever early Interstate that my Dad bought in the early 80's and my Nintendo Gameboy that was a Christmas present in 1992, I have never owned anything by Atari.

Until now.

Ahhh - so small and cute!

This little - and it is surprisingly compact - guy came from eBay. Console only, untested. As usual. It's an Atari 2600 or more frequently known in this configuration as the Atari Junior.

After acquiring a couple of el cheapo games (Road Runner and Pole Position), I attempted to plug it in and see if it showed any signs of life. It's important to know that my usual composite mod wouldn't work since the later consoles mix the audio with the video signal before passing it through to the modulator, so the best I could hope for was to see the power light light up.

First thing, it's 9v DC with a 3.5mm jack instead of the more usual barrel connector. Presumably this was cheap for Atari but you ran the risk of shorting out the console if the power was on and you pulled out the power cable. This is one of those times where you really should follow the 'always switch off the power at the wall before removing the power cable' advice...

Anyway, I got my trusty power supply out with the 3.5mm jack (the same as for the Interstate - but the Interstate is 'tip negative') and checked twice that the polarity was correct for the Atari i.e. tip positive or centre positive. Now, my power supply has a little LED indicator lamp on it that lights when it gets plugged into the mains. But when I plugged it in after putting the cable into the back of the Jr this light stayed dark. How odd.

But I persevered and switched on the console.

Nothing. Nada. Zilch. Zero. Zippo. Dead.

It's dead Jim.

I quickly switched it off and unplugged the power supply from the wall and disconnected the cable from the back. I scratched my head for about 30 seconds before I realised that this was almost certainly a dead short somewhere on the board. After hunting down my multimeter I put it in continuity and started probing around. First thing, try the power socket. Sure enough, the terminals gave a dead short. But where would that short be?

This is one of those times where I got lucky. The board has a large capacitor just next to the power switch so I thought I'd de-solder it and see if it was still good as it was big and easy to get to. So I removed it with my trusty de-soldering tool, and.....the short disappeared. WHAT?

Capacitor - is this a dagger I see before me?

Out came my little component tester. Clip in the cap and press the button... and it says that the 2200uf capacitor is actually a 0.12 ohm resistor. Oh. So the cap has gone bad and gone full short. Again, I fell lucky as I actually had a small bag with EXACTLY the value of this capacitor, even down to the voltage so I was able to easily replace it.

Nope - it's a dead short..

Second time 'smoke test' - power light stays on on the power supply and power light comes on on the console. Nice. Now all I need to do is figure out the best way to do the composite mod.

Well, the power LED works at least...

There are, as I have found out, several ways to skin a cat. Some require minimal components but also seem to be minimally documented, some require kits of parts from nice suppliers on the intertubes. To begin, I tried to keep it simple and cheap.

First, take a handful of resistors and a 100nf capacitor. Add them to the board in the correct config. Attach a wire to the appropriate point on your resistors and then solder it to a new phono socket. Solder a wire from ground to the ground on the phono socket. Job done. (Video of this mod from youtube and can be found here.)

It's not exactly pretty....

Ugly. Urgh.

But does it work?  Kind of...

Meep! Meep!

I can get quite a decent picture but it's only in black and white. Now, the 2600 experts among you may remember that these consoles actually have a switch to switch between colour and monochrome - a definite throwback to when colour TVs were not that common. But I did check and it was in the correct position.

So, it's either that the mod isn't quite right (highly likely), the TV type switch is borked (possible) and stuck on B&W or there is an issue with the video chip (worst case scenario).

Anyway, I also managed to get sound out of it by soldering a wire to pin 13 of one of the chips and then another to ground and connecting them both to another phono socket. So sound and video do both work.

It's Alive!

I still need to dig out my ZipStick joystick (compatible with this as this is the machine that invented 'Atari' style joystick ports - as used by many, many other manufacturers including Commodore for the Amiga), and I will probably look at building a better composite mod or even buying one of the many kits available.

To be continued....