Rebuilding a Funhouse

Trapdoor opens but won't stay latched up

This one is kinda comical. The door tries to open for a Frenzy or loop bonus or multiball jackpot, and then flops shut again. Repeat three times. Since the game knows if the door is open or closed, it'll compensate by counting mirror shots as trapdoor shots. Makes multiball jackpots much easier, but the game is still broken. Time to fix that too.

[latch lip, before] [latch lip, after]

Here are the before and after shots of the latching mechanism. Look at the two screws with lockwashers holding a plate onto the spring-loaded solenoid actuator. (whew!) That L-shaped plate held on by the screws has a bent-out section, which has a shadow on it from the right-hand screw. That section is what the trapdoor lifting crank catches on, to keep the door raised. In the left-side photo, the crank catch (just above the crank pivot point, with the 1/2" diameter bushing) is right on the edge of that section. Occasionally when the trapdoor lift pulled in, the crank catch would fall off the side of the latch. By carefully bending the two small tabs that hold the solenoid actuator plate onto the mounting frame, the solenoid actuator plate (and the L-shaped plate screwed to it) can be shifted to the right, getting more of the L-shaped plate under the crank catch. In these photos, I only moved it about 1/16" over, but so far it's been enough. There might be slotted holes in the L-shaped plate to allow an adjustment without bending, but I didn't try unscrewing it to find out.

[trapdoor down] Here's the same mechanism from the side, better showing the crank pivot point and the latching action. In this photo the trapdoor would be closed. The L-shaped plate is resting on top of the lifting crank arm, waiting for the blue solenoid to pull in and rotate the crank arm.

[trapdoor latched up] To open the trapdoor, the blue solenoid pulls in, which rotates the crank clockwise around the pivot point (bottom center of the photo). When the door is up, the latch mechanism (screwed to the yellow solenoid's actuator plate) drops toward the pivot point, keeping the crank arm rotated, which keeps the trapdoor up. To drop the trapdoor, the yellow solenoid is pulled in, which lifts the L-shaped plate out of the way of the crank arm catch. Then the spring on the blue solenoid (and gravity) closes the trapdoor.

[trapdoor latch missed] If the L-shaped plate is misaligned, it can end up resting on the side of the lifting crank arm, and it won't be able to latch. Here it's shown resting on the side of the pivot point bushing. This would be bad.

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last twisted 9/7/97 by tom