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Atari Video Music Modifications
MUFF WIGGLER Forum Index -> Video Synthesis  
Author Atari Video Music Modifications
In a few days an Atari Video Music should be showing up at my door and naturally I want to modify it. Is there a thread that covers this topic? I would like to modify mine with similar features to the units Switched On were selling (page is no longer on their website hmmm..... ).

Please share your knowledge, video synth gurus!
Hey there!

I designed the modifications for the units sold by Switched On. Unfortunately I have no documentation of them, or time in the near future to get all of that together (I am overwhelmed with LZX stuff.)

I can definitely help answer any quick specific questions you may have, though. There's a patent document and a schematic scan floating around out there you should be able to find, both of which provide lots of information on the unit.

The meat of the mods I did involved giving you level controls over each of the 8 DAC outputs that create the H & V triangle ramps fed into the shape comparators. This allows you to modify the typical diamond shape.

I attempted a MUCH more intense set of mods (voltage control over many internal parameters) at one point, but got very frustrated at the limitations of the unit and gave up on that.

Good luck!
Hi Lars.

First up, hi! My first post here on Muffwiggler. smile

I appreciate this thread is now six, even eight years old eek! however I too own one of these 1970's dinosaurs and would love to know just how it was possible to extract a video out signal from what looks like three bare, parallel jumper cables on the board just down from the AF modulator box. I've looked high and low on the internet, but can't find anything to shed any light on this, even though I know it's possible. Any clues on how to proceed?

Kind regards,


it's somewhat easy figuring out... stay away from CV/Gate in to power legs on chips:P
Yep. Seen all that. And the revised version schematic... and all the rest...

And the rather excellent Ben Heck video... (see below...)

But no video out modifications. So until then, the rest is just 'noize'! ;-)

Tom x

Ummm eye bypassed the modulator encoder circuit in mine and took direct video out.... hey it wasn't outputting anything at all when got it.... until started poking round... if need be can probably pop the lid on it and take fast photo reference... and or look at the schematic again for figuring out exactly where eye grabbed the direct video output
BTW never realized that was any big issue for everyone else.... Bypass the video modulator encoder.... it's the last thing before output..... if remember correctly it's the silver box thinga ma bob... eye have long history inside of video circuits so it was pretty much an automatic response for getting some output going... plus didn't have the old atari2600 demodulation for channel 3 or 4.... took that factor into consideration... maybe eye do actually have one somewhere.... yet finding it is way more of a pain than getting the c240 outputting video
need looking for seeing if eye just left the ground connected on the output cable... pulled the + side... and started circuit tracing backwards until got some stable video output... survey says that's what ended up taking place....
don't recall adding another rca output jack in back of that unit
This was never going to easy was it?! I just want to sell the damn thing, and move on. If I can get it to output video reliably, then that's all I care about.

I noted all the mods done for the 2600 etc, maybe this thing is easier, but I do seem to remember there being some kind of transistor involved in that circuit. Maybe you're right? Maybe it isn't needed? Would love to see a photo of what you did. smile

Eye tagged/soldered video out + onto one of the bare wire "circuit bridge jumpers" in that isolated section directly below the silver box channel RF modulator thingy
So nothing else? No decoupler or transistor or anything like that needed? Positive and ground? There are three bare jumpers.
yes... didn't need adding anything for getting stable video out...
get inside that silver box area... pop the top off of it.... resistor leg...
been a while...

hmm are you just here to get that Atari c240 working & sell it on ebay?
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