I have a Williams Sorcerer System 9 that keeps blowing Q9 on switch column 3. This contains the pop bumpers so it's obvious 1 of them is returning solenoid voltage to the switch column. After replacing the 2N3904 it tests perfect with a switch tester.

I could disconnect power to each pop and then reconnect until I identify the culprit but that seems wasteful. I tried attaching a test lead to the green orange wire and manipulating the spoon and switch to see if I got continuity to any to the tabs on the spoon switch. No luck.

I'm going to try attaching the dmm on VDC to the green orange wire and ground and then trigger the pop and see if the voltage goes high. Of course I'll disconnect the switch columns from the mpu to so this.

Any other tips to try and find the problem without the trial and error?

What a great tip. With 8 switches in the column I should be able to find it in 3 disconnects.

I'll give it a try!

Probably would have worked but no direct short. I have disconnected the column from the 3 pops to eliminate or identify them. My idea about testing the switch for coil voltage did not work either

My vote is on nylon grommet