A friend's Riverboat Gambler is having some problems when it powers up. It starts a cycle of the lift crank assembly on the ramp moves a little, followed by the left drop target solenoid energizing and all the controlled lights will go out and then come back on. I've also noticed that the +5VAC and blanking leds on the MPU board are solidly lit, and the diagnosis led is blinking. The diagnosis and the blanking led will go out when the left drop target solenoid is energized. I've reseated all the connectors on the MPU board and there is nothing that jumps out at me on the MPU board that looks fried. Now when I go into the adjustments and bookeeping settings, the solenoids stop there energizing cycle. Any suggestions on where to start to troubleshoot this?

So I fixed that problem by reseating 1J8 on the MPU board. Now the next problem is the game will reset shortly after I launch the first ball. Also the display is saying press advance when it is powered up. When I check the messages, it says wheel error, and I've reseated the two connectors on the back side of the wheel board without solving the error.

I spoke too soon. The resetting is back with the energizing of the solenoids for the left target bank and the ramp...

The fix was to replace the bridge rectifier on the power supply board, however that was after I recapped the board and replaced Q5 trying to track the problem down the schematic. The next problem was while all the solenoids work in test, most didn't work during gameplay. The problem solenoids were all of them minus the flippers, slingshots and pop bumpers. After I added a little bit of solder to the connector pins/bridge rectifiers on the auxiliary power driver unit board everything was working perfectly.