BYO Atari 7800 Controller - Schematic for dummys

[Wyluli Wolf]

I finished my first 7800 arcade controller. I still need to put finishing touches on it but it works! I'm attaching my "simplified schematic" for the wiring in the hopes that it might help someone out.

 

Thanks to everyone for your input!

 

 

 

 

[Bakasama]

I was wondering where does the C button on the Sega Genesis controller fit on that chart.

[CMR]

Nice work. I wish I had that schematic when I built mine. The one I used was in a text file and kind of confusing.

[Dauber]

Not dumb enough. What are "NO" and "NC"???

 

(I can solder, but man, I can't read a schematic for crap. THIS is the kind of stuff I need!)

[CPUWIZ]

NO = Normally open

NC = Normally closed (in some cases people also use NC as "Not connected").

[Dauber]

Okay, then what is closed versus open??? Is it some kind of thingy you attach that has a switch or something??

[Shawn]

Okay, then what is closed versus open??? Is it some kind of thingy you attach that has a switch or something??

 

Closed is when the switch is making constant contact and you have to press the button to open it. Open is when it's normally not making contact and you have to press the button to close it.

[Dauber]

Ah.

 

How does that transfer over in terms of how you wire it?

[Jinks]

Ah.

 

How does that transfer over in terms of how you wire it?

Use an ohm meter to see if your terminal your wiring is the NO or NC pin as per definition.

Some switches will say by the terminal if it is NO or NC.

What does pin 7 do on the 7800 I see there is no wire going there on the joystick cable. Could it be used for a pause switch?( With internal wiring of course)

Never mind it looks like that is 5v power.

[Wyluli Wolf]

I pulled out my home build 7800 controller the other day and ran into some odd issues. I'm hoping that someone can help me out!

I played Scrapyard dog on the 7800 system and both buttons worked fine. I then tried to play DigDug on the 7800 and the fire button did not respond at all. I put Scrapyard dog back in and both buttons worked fine.

I then plugged the controller into my Atari 2600 and played Asteroids. Both buttons worked fine as fire buttons. I then put in Defender II and the fire buttons did not respond. So it appears that the buttons work fine with some games and not at all on others, regardless of whether it's plugged into an Atari 2600 or Atari 7800.

Any ideas on what might be causing this and how to go about troubleshooting?

I've wired the controller according to my schematic above. The only small difference is that instead of splicing a wire in with the resistors I ran a separate wire directly to the button. So there are two wires connected to the NO connector. One with the resistor going to ground and the other going to 5 or 9 respectively.

[+GoldenWheels]

I wanted to say thanks to Wyuli for the diagram, I used it to successfully build my first 7800 arcade stick (and thanks to Shawn, who sent me some resistors, gratis, with a game purchase because he knew I was wanting to build one)

 

Now...can anyone show me how to add variable turbos to my controller? Ideally, variable turbos for each button? Like, with a wiring diagram a dummy can read?

 

I was going to low rent it and hide one of these in the project box and just pop the knob through the top, seemed pretty easy:

 

http://www.ebay.com/itm/282213786225?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

But the turbo works very poorly with my stick....it will fire once, delay about 2 secs, then go to turbo fire as it should, with each button press. Making it fairly worthless.

[Inky]

I think I may have a little project to do!

[TheDevil'sCompass]

Any ideas on what might be causing this and how to go about troubleshooting?

Did you get this figured out? The only difference I see between your schematic and others I found online is the value of the resistors. I saw one with 520ohm resistors, maybe that's the issue.

[Wyluli Wolf]

I wanted to say thanks to Wyuli for the diagram, I used it to successfully build my first 7800 arcade stick (and thanks to Shawn, who sent me some resistors, gratis, with a game purchase because he knew I was wanting to build one)

 

Now...can anyone show me how to add variable turbos to my controller? Ideally, variable turbos for each button? Like, with a wiring diagram a dummy can read?

 

I was going to low rent it and hide one of these in the project box and just pop the knob through the top, seemed pretty easy:

 

http://www.ebay.com/itm/282213786225?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

But the turbo works very poorly with my stick....it will fire once, delay about 2 secs, then go to turbo fire as it should, with each button press. Making it fairly worthless.

Glad my diagram was of help. I'm afraid I'm not sure on the turbos. Hopefully someone will chip in with some ideas.

[Wyluli Wolf]

Did you get this figured out? The only difference I see between your schematic and others I found online is the value of the resistors. I saw one with 520ohm resistors, maybe that's the issue.

I did finally figure out the issue. I ended up taking apart the controller and starting from scratch. After I tested the the wires with my multi-meter to match them up with the pinout I decided to test my 620 ohm resistors. It turned out they were 620K and not 620. DOH! I didn't have any 620 ohms on hand so I substituted 680 ohm and it now works just fine. Drove me crazy trying to figure out what the problem was.

[Garwor]

Just now getting into this sort of thing and am wondering if anyone could explain to me what the function of those resistors are? I know what the component is, I just mean what their effect is with the controller. I'm trying to cobble together a design that will let me install a switch or two for Colecovision compatibility and want to make sure I understand everything I'm seeing before I get too far.

[briwayjones]

I'll add to this. Here is a page that tells you how to modify Sega pads and joysticks.

 

http://www.instructables.com/id/Retro-Atari-7800-Mod-Sega-Master-System-controlle/?ALLSTEPS

[MaliciousCarp]

Thanks for the simplified schematic! I used it to build my own 7800 controllers out of some 3rd party sega 6-button controllers. They work great.

[MaliciousCarp]

Just now getting into this sort of thing and am wondering if anyone could explain to me what the function of those resistors are? I know what the component is, I just mean what their effect is with the controller. I'm trying to cobble together a design that will let me install a switch or two for Colecovision compatibility and want to make sure I understand everything I'm seeing before I get too far.

 

That is a great question! I wonder if it has to do with pins 5 and 9 being the paddle controller pins from the atari 2600. They go through a resistor to ground or, when the button is pressed, they connect to pin 6.

[Garwor]

 

That is a great question! I wonder if it has to do with pins 5 and 9 being the paddle controller pins from the atari 2600. They go through a resistor to ground or, when the button is pressed, they connect to pin 6.

That's the same ballpark I found myself in when spending a little more time on the issue. Since I've decided to forgo 7800 compatibility, though as I don't have one.

[bikeguychicago]

I love the schematic but I have two additional questions:

 

1. Does it matter how many watts the 620 Ohm resistor is? If so, what is the correct wattage needed (I see anything from an 1/8 watt up a 5 watt ones on the Frys site, for example)?

 

2. What orientation should the resistors be in regards to the diagram above?

Thanks!

[fluxit]

I love the schematic but I have two additional questions:

 

1. Does it matter how many watts the 620 Ohm resistor is? If so, what is the correct wattage needed (I see anything from an 1/8 watt up a 5 watt ones on the Frys site, for example)?

 

2. What orientation should the resistors be in regards to the diagram above?

Thanks!

 

1. No.

 

2. Either. Resistors are not polarized.

[Osgeld]

if you want a more technical answer to 1, a 16th of a watt resistor would still handle the power of the circuit, so anything bigger in terms of wattage is fine

[bikeguychicago]

 

1. No.

 

2. Either. Resistors are not polarized.

Thank you both for the clarifications.

[tripletopper]

I don't know if anyone can explain this behavior, but the 7800 Joystick and Pad of mine work on the Colecoviison, except in one specific instance, to be described later, but the Colecoviison controller doesn't work on a 7800, and I doubt either work on a master system or vice versa, due to a different voltage pin.

 

The 7800 controller works perfectly fine for every 1 button CV game, and every 2 button CV game, (assuming you either don't need a keypad, or y-in an external one) EXCEPT if you need to push both buttons at the same time. The most obvious handicap would be on Tutankham, where pressing both buttons together detonates your "Genie Wish Bomb." No bombs on a 7800 controller.