This weekend, I was helping my dad with his Getaway. We replaced a bunch of bulbs, replaced some coil sleeves, then cleaned it up. When it was finished, we had a switch matrix issue. One whole column of switches would ground short the entire respective row when closed. This was only for one column. The matrix appeared normal when no switches where closed.
We spent about an hour isolating switches and closely examining for shorts or pinched wires. No luck. On the CPU board, we unplugged J209 (rows) and J207 (columns) and manually closed the switches with a jumper. Sure enough, it was still grounding the whole row for the switches in that one column.
So, it appears to be on the CPU board. As for repairs, I am planning on replacing U20.
Is this the next logical step? Are there any other electrical components that I should order in anticipation of repairing that could also be causing this issue?
Final question: Is there a way to bench test this? My dad and his game are 100 miles away. I have his CPU board. I do have a Fish Tales available. Can I install this board in there to verify, or would that cause issues?