So – how to do an Atari 2600 Junior composite modification? Theoretically, you could use an Atari Pico board, which is detailed elsewhere on this blog. However, I found that there was a much easier method which uses less components and to be fair actually works with the Junior.
Note – I’m using PAL Juniors here. I’m unsure about NTSC models, which the majority of the mod boards out there do work on.
The method that I use for Atari 2600 Junior composite modification is not mine – it comes courtesy of the Tynemouth Software blog. It’s a great little mod method and full credit goes to them! The only thing that is my own is the routing of the wires. Note – the image above shows the board already modded and indeed with replacement capacitors. The big 2200uF beast on the left and the small 4.7uF axial one on the right are the common ones to replace. Some PAL models have another three 4.7uF radial capacitors – like this model featured.
Atari Junior Composite Modification
So, I’ll not detail the process – best go over to Tynemouth Software for the full breakdown of how to do it. It essentially is the removal of a resistor (R56) and all of the modulator unit, although to be fair, you could simply take out the power and video signal wires leading into the modulator.
The placement of the transistor is pretty easy – bend the middle leg up and out with a small ‘knee’ joint around 5-10mm from the end so that it points back down. Then, insert the transistor into the holes described:
The 75 Ohm resistor is inserted and the connection ground can be done using the resistor itself:
The ground, video and audio wires tapped off as prescribed and fed through the hole freed up after removal of the modulator. If you don’t remove it, the there are options for feeding the wires through the various holes in the ground area.
Next, I repurpose the RF out phono, grounding it:
Yes – I know I don’t need to do all three legs, but it looks nice!
Then I connect the video output from the mod to the existing phono. even if you don’t remove the modulator, you’ll need to detach the lead that comes from the unit to the phono socket:
At this point, you can test the unit with a cartridge to see if the picture is displaying correctly and if the colour trim needs adjusting. Most of the times with Junior you never have to touch the trimmer pot using this method.
Atari 2600 Junior Composite Modification – Adding Audio Sockets
Then, you just need to add the audio sockets. If you use a 6.5mm drill – the wood drill type with the sharp point and flat drilling edge, as opposed to a standard HSS drill which has angled cutting blades, then I find this works better. Mark off the positions: for the right hand hole, go exactly in the middle between the joystick plug and the RF out. In terms of height, again halfway of the flat plastic area. Then for the left hand hole, mirror the distances you used for the right hand side. That way, the holes will be aligned and you should have just enough space to thread on you phono plugs without impinging on the motherboard. It will be tight, mind!
Note – I painted the existing phono yellow, using a paint marker pen. Works a treat – just needs two coats to cover over the original black plastic. 6.5mm holes mean that you have a little leeway to line them up to finish off the job nicely.
Once that’s done, you can affix the membrane and close up the Junior. Job done!