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DistantStar001

Problem //e board returned to life, but the joystick isn't working right?

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Overall, the computer boots, loads programs, passes self-test, and performs very well, but with one small exception.  The joystick (a 9-pin CH Mach III I believe) isn't being recognized properly.  

 

The board has had some (rather sloppy) work done to it.  All of the RAM sockets, as well as the sockets for the EF-ROM and the S02 chip, have been replaced.  Some of the traces from the RAM chip at F6 are broken, there are a number of bodge wires in their place.  Also, one pin seems to be free floating.  However, I've checked all the connections, and everything seems to be connected.  Also, as mentioned, the computer is more or less fully functional now!  All and all, given everything that has been done to this board, I'm taking an "if it ain't broke, don't fix it" attitude to this.  However, the joystick is the one lingering issue I have.

 

I've tested both the stick and a set of Apple-branded paddles on this board, as well as on 3 other working //e's and a //c.  Both work perfectly with the other 4 computers, but not this board.  

 

MECC Computer Inspector isn't recognizing anything connected to the port (I also tried a 16-pin Mach III as well).  In games (Centipede, Star Trek SOS), the stick automatically goes to the lower-right corner but the games do respond to input from the stick (up, left, down, fire).  

 

When tested on the other computers, MECC Computer Inspector reads the stick as slightly off-center (jumps back and forth by a pixel or so every 15 to 20 seconds) but it's not enough to affect gameplay.  So, at this point, I'm pretty sure that it's not the joystick.  

 

I suppose I could just accept that this thing won't be a gaming machine...  But then, this thing is so close to being fully functional, why give up now?  If anyone has any ideas, it would be very much appreciated.  

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A first step would be getting schematics and tracing back from the game connectors to wherever they go. Along the way you may find something, or end up at the faulty component.

 

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Any idea where I could find that?  Specifically relating to the joystick port?  I've found several online, but those seem to be for the logic, and don't specify the port.  So far, all I've been able to determine is that pin 5 is for the X axis.  I'm probably going to try and trace the pin on the board itself through any passive components to see if one failed.  The relevant schematic might make that search easier.

 

I've also looked at the SAM's Apple II/IIe Troubleshooting & Repair Guide, but all that was able to tell me is that it's not an IC problem (swapped all the related chips with no effect).

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OK!  Figured it out.  It was the 558 all along!  I could have sworn that I tested it in another board, but I guess not.  Anyway, Thanks for the help.

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