I have just replaced a number of blown transistors on the switch matrix on a stern high roller casino. As a result I now have all the switches working but now there are still a handful of switches that trigger 2 or 3 other switches on that column when a single switch is triggered in test.

This occurs in around 3 of the columns. This machine had switch issues when i got it. Now most of the issue has been resolved but I am not sure where to look next for this problem.

Any feedback on next steps would be great.
Thanks in advance.

Sorry I should have mentioned that I have tested the board after the repairs and the matrix works as it should. So it is a playfield issue.

I am mapping out the problem switches now. I will then look for shorts or problem diodes.

I have done some more investigation and now have an issue where if a switch on row 3 is triggered it also triggers a switch on the same column but in row 6.

I have removed the connectors for column 1 as this was also causing an issue across row 2. By removing the connector the issue across row 2 has gone but the other issue still remains.

Any advice on next area to check would be great.