. . . as soon as it powers on. Even before it enters attract mode. And even after game over.

MPU led flashes appropriately (flicker/flash + 6 flashes). In solenoid test, K1 relay does not click. But I wouldn't expect it to, because it has already enabled the flippers.

Everything I've seen about troubleshooting the K1 flipper enable circuit is based on determining why flippers are not energized. So the quick jumpering and continuity tests don't help me because current is already flowing. I did them anyway. I've compared the readings of components in the circuit with other components on the board that are the same and all readings are consistent.

So I've got three questions: Is there an easy way to test the functionality of the K1 relay itself? Could the problem not be on the SDB and if so, what/where should I check next? And, is there anything else you can suggest based on your experience/knowledge?

FYI -- I mention this in case it's related -- In the switch test, all the roulette wheel switches are giving me errors (any of #2 to #5 shows every time I run a switch test), even though the wheel is not giving me any problems in play.

Game plays just fine, except that the flippers are always energized. Guess it's better to an issue that doesn't affect game play, but I'd kinda like to get this fixed.

Any advice would be appreciated.

Thanks in advance.

Thanks for the direction! Here are my measurements.
For 'Off', game was in attract mode. For 'On', a game was initialized.

As the flippers are always energized, I am not surprised that most measurements are consistent with your 'Flippers On' voltages. However, U4 pin 3 reads correct in the off position.

Interestingly, when testing U4, my probe contacted both pin 3 and pin 4 and the relay responded, so I know it's not seized.

Is this telling me my issue is not with the relay, diode or transistor, but rather with U4?

measurements (resized).png

I disconnected J4 from the SDB and the flippers are still enabled.

With J4 disconnected, U4 pin 3 reads 0.8V.

Yeah, readings are the same: 0.125V.

Sorry. It is a diode reading and is consistent across U1, U2 and U4. Voltage reading with power on was 2.03V on U2 and readings on U1 and U3 are 0.43V and 0.41V respectively.

By following along with the schematic, I was able to understand your step-by-step diagnosis. I've already sourced a replacement IC. Thank you for taking the time to help. Much appreciated!

Sorry for the delay. Part only arrived this week. I am pleased to report that all is good again. Thank you for your assistance.