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Trouble with Apple IIc and joystick control

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I have three working Apple IIc computers but one of them acts weird with the joystick input.

 

In the game Tumble Bugs I can't move down. I tried Gremlins and I can walk up, down, left, right, and all the diagonals, but not right and down.

The character just walks to the right. I'm sure if I keep trying games I'd find more with troubles moving in the down direction.

 

Any ideas what would cause this problem?

 

My other two work just fine. Unfortunately I don't have any other Joystick to try. I only have a CH stick.

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Have you tested the calibration of the joystick?

 

Enter into applesoft basic and run a program like this:

 

10 PRINT PDL(0)" "PDL(1):GOTO 10

 

Adjust your joystick until both pdl(0) and pdl(1) are at 127.

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Shouldn't be the stick. My two other IIc computers works fine with it. Has to be something on the main board.

 

Sent from my Windows Phone 8X by HTC using Board Express

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Check the pins on the connector. One may be bent down.

 

Thats the thing though. In most games I can go down just fine. It is like the maximum analog value can not be reached.

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Check the joystick/mouse port on the troublesome //c and see if something might be stuck in one of the holes that the joystick pins don't go into. Failing that the problem is something on the motherboard.

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Check the joystick/mouse port on the troublesome //c and see if something might be stuck in one of the holes that the joystick pins don't go into. Failing that the problem is something on the motherboard.

 

It is for sure something on the motherboard. I'd like to know what so I could replace whatever component is causing the issue.

 

Sent from my Windows Phone 8X by HTC using Board Express

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Have you tested the calibration of the joystick?

 

Enter into applesoft basic and run a program like this:

 

10 PRINT PDL(0)" "PDL(1):GOTO 10

 

Adjust your joystick until both pdl(0) and pdl(1) are at 127.

 

 

holy crap, this is the greatest thing I have ever learned about an Apple II.

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Thats the thing though. In most games I can go down just fine. It is like the maximum analog value can not be reached.

I don't have detailed knowledge about how the Apple II does it's A/D conversion but that's where I'd start troubleshooting based on the given information.

 

 

 

Block Diagram of A/D converter:

http://www.umich.edu/~archive/apple2/technotes/tn/aiie/TN.AIIE.006

 

Could be a bad cap.

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I am going to bring this thread back from the dead! 

So I got. CH Mach III hooked up to the Apple IIGS, and as I am trying to calibrate it, it doesn't exactly bounce back to 127 127.  Nit sure if there is some way to tighten that down or not.  But I also notice as I move it around to the edges, it should go 0 0 (upper left) to 0 255 (upper right) to 255 255 (Lower Right) and then 0 255 (lower left)  but the lower left somehow goes 'up' a huge amount to 0 135.  Which the computer should interpret as pretty much going left.

If I load up Donkey Kong, it just runs to the right.

Any ideas?

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