Today I tackled the GameCube Portable problems once more. While JediBoy was off doing other things, I spent a few quality hours with a soldering iron trying to sort out the mess that we call The Goddamn Right Trigger (TGRT).
In the last episode, we suspected the problem with TGRT was either the controller board or the potentiometer ('pots' for short). So, I spent some time de-soldering the old controller board and installing our spare in its place. The problem with this approach, of course, is that it can cause more problems than it solves.
I got to the point where the spare board was in place and the Left Trigger was attached. It all worked, so I was at least back to where we were 90 minutes before. I then wired up TGRT and.... failure - as in: no change from before.
This points to a pots problem since it's unlikely that 2 controller boards would have the same issue with Right Trigger support. This also confirmed something I thought I saw a few days before. Just for fun, I attached a multimeter to the Left Trigger pots and tried to measure the range of resistance. I then did the same with TGRT pots. I didn't really know what I was doing, of course, but the ranges I saw were quite different between the 2 triggers.
This difference could be explained by the fact that the Left Trigger pots came from a Nintendo controller while TGRT pots came from an OEM controller. Same style of pots components, different resistance ranges, different controller boards.
As the dust settles around me and that vein in my forehead throbs, it seems like the best course of action is to get another Nintendo controller and rebuild TGRT using genuine Nintendo parts. In hindsight, this all seems commonsense, even if we took a few weeks' detour to get here. So, to Kijiji and eBay we go!