A1200 Joystick Port "Up" direction not working

[thgill]

Recently received a mint condition A1200 and tonite I discovered that the Joystick "Up" direction doesn't work on Port #2. Mouse and both buttons work fine on the first port.


All other directions including the fire button work fine. This is the first time I have ran into this issue so I am not sure where to begin troubleshooting this.

I did a quick google and found mention of possible CIA problems.



Ideas on where to begin?

 

[robinsonb5]

If I'm reading the schematics (http://www.ianstedman.co.uk/Amiga/schematics/body_schematics.html) right, the direction lines for both joystick ports go to the Lisa chip via a 74LS166 serial shift register (which on my 1B1 board is just above the trapdoor slot.)

Port 2's up direction should go to pin 10 of this, so in the first place try buzzing that out and make sure there's no disconnection. If there's good continuity, maybe the 166 is dead?

 

[thgill]

I tried buzzing out pin 1 of the 2nd joystick port to pin 10 of U34 with no success. However it doesn't work on any of the other pins either and they most certainly work.


I am using a 1D4 board in this machine also in case thats important as well as a modded ATX power supply.

 

[thgill]

Tried a second modded PSU with the same outcome, so looks like the psu isn't the issue.

 

[robinsonb5]

I tried buzzing out pin 1 of the 2nd joystick port to pin 10 of U34 with no success. However it doesn't work on any of the other pins either and they most certainly work.

Looking again, there are resistors inline - so try measuring the actual resistances?

 

[Jumping Anaconda]

A few questions to rule a few things out:

1, What software are you testing the joystick with?
2, This one might seem obvious, but have you tested the joystick in port
one?
3, Have you tested the joystick in other machines?
4, What model is the joystick?
5, Have you tried more than one joystick?
6, Does the mouse work ok on Port 2? (Lemmings in two player mode might be a good thing to test that with).

 

[thgill]

Problem resolved!


Thanks to Toni Wilen's help @ EAB, I have tracked down the issue.

I found that one side of the E365 SMD resistor wasn't soldered down correctly. There was a gap about as thick as a sheet of paper between the end of the resistor and the solder on the pad.

Quick swipe of the soldering iron on it and all is well and joystick UP is working fine again.

This might be a manufacturing fault from new.

 

[cosmicfrog]

\o/