Different customers liked more or less noise.

If/when the bell rings is one of the variations between models of an 873. There may also be a terminal strip in the top compartment with 20 and 10-1 on it for connection to a light tower. The blue wire is the 6V fused power, so the bell should be 6V. The bell is mounted inside the cabinet above the handle release relay with the round bell part towards the front of the game and the coil towards the rear.Ĭonnect to blue wire 20 and red wire 10-1, which should be in the wiring harness nearby. There's exploded parts diagrams for the 873 in the bally 400 manual ( ) The dashpot switch is operated by the u-shaped bar that goes into the cylinder. the dashpot is the air cylinder damper on the right side of the reel mech. It allows a coin to register until reel 1 latches during the spin, and is mainly intended to register a coin stuck in the coin mech that went thru due to the shockwave of the reel spin kickoff. is a microswitch activated by the reel 1 wiper arm. When the payout counter steps off the powered trace(s), payout ends. payout happens when a circuit completes thru the reel wiper boards and payout counter to power the payout relay. the payout counter is mechanically stepped by a coin exiting the hopper, and electrically reset the coin relay and handle release relay are electrically tripped and mechanically reset

To make complete sense of the schem, you need to know: the EOS switch opens, unpowers the line unit relay and that in turn unpowers the line unit step-up solenoid to step the unit. when the coin switch goes back up, circuit completes thru a different line unit relay switch to power the line unit step-up solenoid coil second+ coins cause the line unit step-up relay to power when the coin switch goes down, and a hold switch on the relay keeps the relay powered until a line unit EOS switch opens.

first coin resets stuff and trips coin relay and handle release relay The line unit step-up is a little indirect: probably the line unit not stepping up reliably due to electrical issue, but it could be mechanical. If you're familiar with bally EM pinballs, you won't have any trouble tracking down the issue.

Assuming it's really an 873-ZC and not just the model/serial number plate, the paperwork is in

Bally 873 slot machine tilt reset