Hi!
I've got an Amiga 500 where the mouse and joystick ports have stopped working properly. The mouse only goes right and down, and the joystick only goes left and right.
From searching on google, I found that the problem might be the multiplexer, or the Denise chip.
I replaced the Denise chip with one from another, working machine, and desoldered the 74hc157 mux and replaced it with a brand new one. The exact same issue remains :furious:
I then started logic probing the board, and found that while both X and both Y signals from the mouse, and all 4 directional signals from the joystick reach the mux, only left and right from the joystick port and only 1 signal of each axis from the mouse exit the mux.
Thus I get the idea the mux isn't switching between the inputs as it should. I followed the A/B input from the mux to pin 6 of an "octal tranceiver" next to Denise. The connection to the transceiver has a resistance less than 1 ohm, so that should be fine.
I don't know enough about the hardware to determine what should be providing the input to the transceiver, or what else could be wrong.
Can any of you help? Anyone who has had similar issues?
