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Rajada

Atari 2600 Paddle Controllers Diagnostics

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I own an Atari 2600 heavy sixer and I'm looking for a little help diagnosing a problem. I've bought two sets of used paddle controllers (two controllers attached to one wire) and neither has worked. My problem is, I don't know if my controllers, or my joystick ports are to blame. After disassembling all four pots and cleaning them, there is no change.

 

So I looked up a pinout of the 2600 joystick ports, and found this little number.

http://atariage.com/forums/uploads/monthly_05_2014/post-32232-0-25905600-1400246916.gif

I do happen to have the Video Touchpad controller, and testing it with Star Raiders shows it is in perfect working condition. I notice that pins 5 and 9 are shared by the touchpad and the paddles for input. If my touchpad works fine, am I correct in assuming that this eliminates the possibility of my joystick port(s) being bad?

If so, what the heck is most likely wrong with my paddles? Where do these things fail most often? I'm looking to fix them, but I'm not sure if it is feasible.

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If the rotaries are totally not working after attempted cleaning, my theory would be that possibly the +5V or Gnd connection is severed.

 

The buttons correspond to joystick left/right - if the buttons don't work then Gnd would be very suspect.

 

Keyboard/touchpads use multiple features of the joystick ports including those used for pots, so if it's working you'd probably expect paddles to work also... though you'd really want to test both on the same controller port to be sure.

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Ah, it is of note that the buttons work fine on all the paddles, as well as all normal joystick functions.

Edited by Rajada

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That leaves the +5V supply, without that there's no effect to paddle buttons but the pots won't function.

 

If you could test the pots with a multimeter it'd help eliminate them as suspects too.

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I'm more concerned that the problem lies between the pot and the console, as I've used replacement pots in other cases. What if I stuck multimeter probes into the correct metal barrels in the paddle's connector. Could that potentially tell me wether or not there's connection there? Is there a safe way to test the +5v pin as well? Excuse my ignorance with multimeters, I haven't taken circuits class yet.

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You could test totally safely using the DMM on the controller without it attached to a console.

 

Test the +5V and Gnd continuity from the plug to where they're soldered to the pot. Test that the pot returns variable resistance when turned.

Then see if you can get the same variable resistance at the plug pins for the pot and +5V.

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I could use some more specifics on how to test the +5v pin on the controller port. I'm pretty sure the paddles are good, so at this point I want to know how to test the pin without blowing out my Atari. My prevailing theory would be that there's a busted part or breakage on the board that only affects the +5v. BUt I don't have the neccessary knowledge to decipher a ciruit diagram.

Edited by Rajada

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I found a point of suspicion on my main board. These two parts don't look original. As seen from the underside, there's a layer of sticky tape-like residue, and the solder looks hand-applied.

 

Board2.png

From the top, there's no solder connecting the little bridge between the two elements. Compared to another picture, this seems wrong. Any thoughts on this?

 

Board1.png

 

Original? board:

http://www.hardwaresecrets.com/fullimage.php?image=45282

Edited by Rajada

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Those solder joints do look a little odd. They're not necessarily bad, but if it were my board I'd re-solder those just to be sure.

 

You should be able to measure the voltage between pins 7 & 8 to test the +5v to the port. I'd find an old cable to plug in there so you can separate the wires leading to pins 7 & 8 from each other to prevent shorting while trying to measure the voltage. It would be really easy to short something if you try to probe those pins directly with multimeter probes.

Edited by BigO

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"Odd" is right, at worst there's no connection between the two parts there. Any idea what parts these are? I'm looking all over for parts that look physically damaged and I'm not seeing anything else.

Unfortunately, I don't have an old cable. My collection of controllers is very small. Do you happen to know what colors of wire represent pins 7 and 8 in a paddle controller? I have one that I cut apart to install a new pot in, and I figure I could use that.

EDIT: Apparently C206 and C207 are audio related.

Edited by Rajada

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The paddle caps are near the controller ports, under the cartridge connector:
post-10599-0-69982500-1423129460_thumb.jpg
You should check the controller cable continuity first, because it's far more likely that your problem is caused by a broken wire and not by the console itself.

Could you be more specific on how your paddles don't work? What game did you try them with? The players don't move at all or are jerky? Is there any change if you plug/unplug the paddle while the game is running? Did you try a 4 player paddle game, and if so do the paddles in the second controller port behave the same?

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I don't know that the colors are always the same, but you can figure out where to probe in the paddle controller using this schematic:

http://atariage.com/2600/archives/schematics/Schematic_2600_Accessories_Low.html

 

 

And, what alex_79 said. What sort of problems are you seeing with your paddle controllers? I assumed from the questions you were asking that they are completely non-functional.

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Since you've opened the console up, it's easier to just probe on the motherboard rather than fiddling about trying not to hit wrong pins on the ports or stripping controllers apart to get to the wiring.

 

I'd verify the controllers though, of course if you had another machine like an Atari or Commodore 8-bit computer then it'd make it a lot easier to test.

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Okay, so I found the issue...

Testing the paddle controller with a digital multimeter on 200k ohms mode with probes stuck into (left to right, up to down) hole 1 and 8 returns the variable resistance of the pot in the right controller. The same method but in holes 1 and 6 returns the variable resistance of the left controller's pot. The resistances max out at roughly 791, and min out at 1. This seemed to eliminate the controller as the culprit.

 

When I opened my machine, nothing seemed amiss let alone those werid solder points, but my audio works fine. In fact, the internals of the machine weren't even very dusty. It was is surprisingly good shape for a heavy six. One of the joystick ports did have a little cracked plastic in around it, so I suspected the ports may be the issue.

 

Unsurprisingly, it ended up being the controllers. But it wasn't the part I expected. Turns out the little metal barrels inside the controller's end are so malformed and beat up that one has to wiggle them a bit until both pins that control the pots make good contact. I may be in the market then for some newer ones, that hopefully won't require the amount of finagling that these ones do.

 

I'm just happy nothing was wrong with the board. Really dodged a bullet there.

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Rather than buy a new set of paddles, you SHOULD be able to get replacement cables from Best Electronics. I haven't had to order that particular cable, but I'd be surprised if they don't have them.

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