I did not buy the optional “Stimulator” to test the board with. I didn’t buy one the last time I built a Megasquirt either, for the same reasons. If you read the assembly instructions, you’ll notice it has you build the MS in distinct sections, and then test each of those sections. By the time you get done, you know the thing will work because nothing has gone wrong along the way. So here is the board with just the 5v voltage regulator section built. I’m testing for voltage per the instructions. 4.94 is perfect, would probably read 5v on a cheaper meter, the Fluke is just very accurate.
The next step was the serial port controller. I tested that by hooking it to my laptop and running a terminal program and seeing if the characters I typed would get looped back to me. They did. After that came building the clock unit, the part that generates the frequency that the CPU runs at. Once that was built I was able to install the CPU and connect to it with Megatune. That worked too.. And so on and so on. Like I said, there’s really no need for the stimulator.