ColecoVision P2 joystick issues

[Jess Ragan]

Years ago, I accidentally tore the player two joystick port out of my ColecoVision while plugging in a controller. Back in 2008, I tried replacing the port with a new one, without success. I thought maybe the port I'd used was faulty, or that I'd soldered it into the system improperly, so I recently removed it and soldered in a new one, taking care to carefully solder in each pin. Thinking I'd licked the problem, I turned on my ColecoVision, and... nope, it's still not working right. I can't enter the secret code in Pac-Man Collection to unlock Pac-Man Plus, and when playing the game with the second controller, Pac-Man veers right, unless you hold the controller left. The ColecoVision ignores all other input.

 

Anyone have any ideas as to what might be wrong? All I can think of is that either the chip that handles the I/O for the second joystick was damaged, or that I somehow lifted a trace on the board when the port was torn out all those years ago. Any help would be appreciated!

[bust3dstr8]

Check the resistance of the I/O lines to ground and +5V. Ground should

be open and +5V should be in the 5K-10K range.

Check continuity to chips, resistor networks, caps...etc.

You can also solder a wire to ground and test the I/O lines seperatly.

If you suspect a chip. download the datasheet for it (if it's a standard TTL) or hopefully find the pinout if it's a custom.

Then check the logic with a probe and compare with the truth table.

Edited May 10, 2013 by bust3dstr8

[Jess Ragan]

Thanks!