Bally knockout no outhole bonus

Pitas_arcade

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My Bally knockout has been broken for 3 years I think it's time to fix it. The coil closet to the playfield on the bonus unit got stuck on and burnt out. I replaced it a few years ago and I got it to not stick on. But the outhole bonus does not work. The "bonus coil is buzzing a bit and when I manually actuate it it doesn't do anything. I am really lost when it comes to em troubleshooting. It's probably a stuck switch somewhere? Where should I start?
 
One thing I noticed is that your coil sleeve is too long and is likely preventing that armature from completing its stroke.

You should be able to manually move the step up and step down coil plungers and increase or decrement the bonus unit.
 
One thing I noticed is that your coil sleeve is too long and is likely preventing that armature from completing its stroke.

You should be able to manually move the step up and step down coil plungers and increase or decrement the bonus unit.
It hits the coil stop before it touches the sleeve. Everything moves like it should.
 
There are 3 bonus relays. It appears that the bottom one is the Bonus Score relay. Which one is the top one?
 

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Based on the wire colors it should be the bonus zero relay which will be engaged, and thus buzzing, whenever the Bonus Unit Zero switch is closed.

Does the Bonus count up during gameplay?
 
as you manually increment the stepper the bonus lights should sequentially light, unless the bulbs are all dead, or the rest of the playfield lights aren't working either.

We need to make sure that the stepper is capable of incrementing and decrementing properly and not gummed up or otherwise compromised.
 
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as you manually increment the stepper the bonus lights should sequentially light, unless the bulbs are all dead, or the rest of the playfield lights aren't working either.

We need to make sure that the stepper is capable of incrementing and decrementing properly and not gummed up or otherwise compromised.
The rest of the playfield lights work. When I manually advance it the lights do not come on and the bonus doesn't add up to the score when the ball drains. I can film a video and post it here
 
Clean the applicable relay contacts with a flex file. Adjust them with a contact adjustment tool.
 
That won't solve his issue if the bonus unit is gunked up/not functioning properly.

I'm still waiting to see if it operates correctly.
This is true, but I've seen contacts on the relay stick shut and cause this symptom on EM machines.
 
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