So I'm gonna go ahead and try to document (and pray for help) on some of the Star Rider PCB issues I've got going on.
Right now, I have two complete, not working, PCB sets. One is mine, one belongs to a friend. I'm going to try to get both working.
I think it's wisest for me to start at the CPU board and move out from there.
It seems like one CPU board (my friend's) is at least mostly working. When plugged into either board stack, it will go through the VGG test and RAM test, but then crap out on the ROM test. So at least it's doing something.
My CPU board is the one that is more heavily corroded. Right off the bat there were a lot of problems. Two dead ROMs, three dead RAMs, and a dead CPU.
I replaced all of that, but I was still getting just a white grid screen. No activity from the CPU. I noticed that the reset circuit wasn't working properly, which makes sense because it was in the most heavily damaged corrosion area. I rebuilt the reset circuit, and it seems to be working properly now, but the (tested good) CPU still isn't doing anything. I don't see any activity on the RAM or ROM, and when connected to either boardstack.
It's definitely getting clock... I can see the Q and E signals going into the CPU and toggling my logic tester, and RESET is high measured on the CPU, but it still won't do anything at all. What could I look at next here?