Try this with power OFF to see if you have a shorted transistor.
Measure resistance from the tab of Q83 thru Q90 to either the board screw or to the ground braid. From what I see on my Corvette, all these transistors have high ohm reading.
If Q83 is measuring quite a bit lower ohm reading than all the other 7, then disconnect J133/J134/J135. If you have the same low ohm reading on Q83, then the transistor is shorted on the board and needs to be replaced. If the short went away, then you have an issue under the playfield.
Omaha, NE
