Joystick suddenly does not work

[grondinm]

Hello,

So all of a sudden my joystick no longer works. I was using it no less than 10 minutes ago. Load a different game after a power cycle. Nope joystick does not work. Is it the joystick or the port on the VIC? I don't have another joystick(or vic)to test. Does one have more of a chance of failing than the other? Without buying another joystick(or vic) can i somehow diagnose?

[Mike]

With the VIC-20 switched off, please remove all other peripherals (drives, cartridge, user port attachments) except the joystick.

In the Denial-WIKI, there's a small test program that you can type in and which reports all four directions + fire. Please try it out and report the results.

[grondinm]

So now i look like a fool...typed in the test program and everything worked. UP,DOWN,LEFT,RIGHT,FIRE

Then i tired loading the game again and everything was fine...not sure what happened earlier but i swear it was not working. Had tried multiple times with different games and had no input.

Thank you for taking the time to answer and providing the link to the wiki.


EDIT:Maybe i had the play button on the tape drive still pressed in...which i just read can interfere with joystick functions...

[Mike]

Maybe i had the play button on the tape drive still pressed in ...

That was one of the reasons I asked you to remove all peripherals.

which i just read can interfere with joystick functions ...

Yes, the tape sense signal is also read by one of the VIA registers shared with joystick operation. Badly written joystick routines compare whole register values and fail. In this case (tape play button down) even the SYS65017 command mentioned elsewhere doesn't help.

[grondinm]

Alright well so after working yesterday today the joystick does not work again.

Running the test program from the wiki with nothing else connected results in no output...Is the VIC or the Joystick at fault?(I'm afraid of the answer)


EDIT: And once again now it just works...i don't understand what is going on. Nothing different between when it was not working and now...unless i'm oblivious to something I'm doing different...I think I'm going to source another Joystick and see if this ghost issue starts up again.

[Mike]

If *all* directions *and* fire change between working and non-responsive it is somewhat unlikely that one of the VIA chips is defective: right is sensed by one VIA, all other directions and fire are sensed by the other VIA. For the moment we rule out two defect VIAs.

More likely is a semi-broken wire in the joystick cable, the one which connects GND. If that fails, none of the joystick contacts can signal anymore. Just moving the cable around can already change it between working and non-working state.

At last, there might be cold solder joints, either with the joystick port (again, the GND pin) or where the GND wire of the joystick cable is connected to the joystick PCB. What type is your joystick? It is a simple one with just switches or a more complex one with auto fire perhaps?

In any case it's definitely easier for you to source another joystick and first check with that before proceeding further.

Good luck!