Definitely no bent pins, the 68k never left the board but I checked anyway. My first thought was the processor, but it still seems like quite the coincidence that it would die mere hours later after testing, but things happen. My plan when I get home is to check all the caps since that is something I altered, then zero in on the CPU since I'm getting power. Is there any information or guide on how to properly check CPU functionality? I'm getting into uncharted waters for my skillset but want to learn more.
First of all, just to make sure sockets aren't the problem, I'd try removing each socketed chip, blowing the socket out with compressed air, and then reinstalling the chip again.
Also, generally speaking, make sure your DIP switches are all set off, that the board is receiving 5.0V from the power supply, and that you're using a System 16 to JAMMA adapter (System 16 isn't JAMMA).
If the board still doesn't boot after that, you can check CPU functionality with an inexpensive logic probe, such as this Elenco that I use:
https://www.amazon.com/Elenco-Electronics-LP-560-Logic-Probe/dp/B000Z9HAP4
Once you have a logic probe, do the following:
1) With the power off, connect the positive lead of the logic probe to a 5V source on the board. Connect the negative lead of the logic probe to a Ground source on the board.
2) Set the TTL / CMOS switch on the logic probe to TTL. Set the MEM / PULSE switch to PULSE.
3) With the power on, place the probe tip against pins on the 68000 CPU and monitor the activity:
Pin 14 = Vcc = High
Pin 53 = GND = Low
Pin 15 = Clock = Pulse between High and Low
Pin 18 = Reset = Should read Low briefly at power on, then go High.
Pin 17 = Halt = Should read High at all times.
Pin 29 = A1 = Should pulse between High and Low as the CPU changes addressing on the bus.
Pin 5 = D0 = Should pulse between High and Low as the CPU reads and writes data on the bus.
If Pin 14 and Pin 53 don't read as expected, the CPU isn't getting power correctly. Check for bad caps or a short.
If Pin 15 isn't pulsing then the CPU isn't getting the clock signal it needs to operate. Check for bent pins on the CPU or damaged traces on the Clock circuit.
If Pin 18 never goes Low or is held Low all the time then the CPU isn't getting reset properly. The CPU needs to be Reset once at power on to start processing. Check the watch dog circuit.
If Pin 17 is Low then the CPU is being halted. Check for a circuit short to ground. Some games have a Halt function that can be set with a DIP switch - try setting all DIP switches off.
If Pins 29 and 5 aren't pulsing then the CPU isn't processing. Assuming everything else is in order, the CPU likely processed code for a short while, then crashed.
I made a tutorial video a while back on using a logic probe to diagnose a faulty EPROM - it's the same principle here, just with CPU signaling instead of EPROM signaling. Check out the video to see how the logic probe behaves when probing a circuit.
View: https://youtu.be/2PAtTIAijeA