I need help solving a non-working solenoid problem. I am working on a Shaq, Gottlieb System 3. The only solenoid that DOES NOT fire during game play or the solenoid self test is the Plunger Gate on the right ramp. It is Solenoid 6, Q7 on the driver board. The machine has a new Rottendog driver board, new solenoid, good fuse at F22, and the coil DOES fire when grounding the Q7 metal tab. All appears to be good from the driver board to the coil. I have also verified the ribbon cable from CPU to driver board is good. I suspect something on the CPU is not telling the coil to fire, but I’m not sure how to test for it. I have a DMM and logic probe, but could use some help diagnosing this problem. Thanks!

Thank you for the response. I wanted to give a quick update. Prior to this post, I discovered the wires to solenoid 6 (plunger gate) had been soldered on backwards. This blew transistor Q7 on the driver board (and fuse F22). I replaced the fuse and installed a new IRL540 transistor. The transistor tested good, but still couldn’t get the coil to fire in solenoid test or during game play as noted above. Long story short, out of desperation, I replaced the new IRL540 with a known working IRL530 and all is well. Not sure if I had a bad transistor or a compatibility issue with the IRL540. In any case, Shaq is back!