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FB2 - homebrew paddle problems

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I downloaded the CX2600 controller schematics from the Archives section of the site to make myself some home-brew paddles for the FB2, as my only other set are somewhere 2000 km away (and date back to my original four-switch model circa 1979). A few old mice, some 1 meg linear pots from (the store formally known as) Radio Shack, some telephone cords and a duplex phone jack, and my paddles are done! (photos to follow, pending resolution of problems)


I've verified the wiring as per the drawing:


- left fire button between pins 4 and 8

- right fire button between pins 3 and 8

- left pot connected between pins 5 and 7

- right pot connected between pins 9 and 7


I've also verified that electrically, everything works:


- normally open-circuit between the fire button pins, continuity when pressed

- continuity across the pot pins when the pot is fully CCW, approx. 1 megohm when fully CW.


I also verified the pin ordering using one of the FB2 joysticks - the illustrations on the schematic refer to the controller connector facing you.


I then fired up the FB2 and loaded the paddle diagnostic program.


The pot measurement seems to be OK (30 when CCW, 0 when CW).


For some reason, however, it seems to think that the fire button is pressed all the time.


If I go to the regular FB2 menu, the menus scroll by when the paddle is plugged in. This lends weight to the theory that there's a wiring problem.


Is there an oops with the drawing as posted? Is the fire button supposed to be normally-closed? Or do I have an odd intermittant problem that appears when I hook up the controller, and goes away when I return to my workbench?

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do I have an odd intermittant problem that appears when I hook up the controller, and goes away when I return to my workbench?


This is the most reasonable conclusion of those offered. It's probably a very similar type of gremlin. It could be an intermittent sticking in your buttons which has so far only happened while your paddles are plugged into the console, or a short within the plug that happens as the controller is plugged in (but clears itself again when unplugged).

Edited by A.J. Franzman
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I feel so stupid. :)


After rechecking the wiring, I decided to flip the leads on my meter, and voila, some of the leftover circuitry on my mouse was imposing a diode across my fire buttons.


Thanks to dumb luck, that diode was forward-biased when connected to the FB2. D'oh!


After hacking out some ICs and photodiodes, it works much better now.


I have to switch legs on the pot (so that fully CCW is 1 meg and fully CW is 0 ohms) but other than that, I'm in business!


Photos and instructions for those who want to build their own will follow shortly!

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Cool. A little Rube Goldberg, but definitely cool. From the sounds of it, people around here are really looking for someone to sell them new paddles to use with their Atari Flashbacks. (You can include me, BTW. It would be pretty cool to get my hands on a pair, but only if it's less than the cost of the Flashback itself.)


I don't know if this helps or not, but you can design yourself some quality parts using these two sites:





You can do up a few proofs of concept to make sure they work and the price is low enough, then take pre-orders for the controllers. If you get enough pre-orders to meet your price point (say, around 100 units) you could put the orders through and ship everyone a brand new paddle!


Just an idea, anyway. :)

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I guess I've watched too many episodes of Junkyard Wars. : )


I agree, they're clunky. My motivation was "How can I do this using as much junk as I can find in my spare parts box, spending as little cash as possible?"


I actually work at an electronics design & manufacturing company. PCB layout and milling can be done on-site. What concerns me with designing and selling anything that's electrical in nature is liability. Of course we're only talking about a potentiometer and a few switches, running off of a SELV, extremely current-limited supply, but things can still go wrong and I can't afford to get sued.

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