Location: Highlands Ranch, CO.
Symptoms: Ramps tries to lower even though it’s already down; delivers two balls into shooter lane.
After checking the mechanical operation of the ramp and running switch tests, I concluded (or guessed) that the microswitches on the ramp and ball trough were acting intermittently.
Sometimes when a machine acts weird like this, you have to think about what the firmware is attempting to do. In the case of the ramp, it tries to lower the ramp because it hasn’t sensed that it has been lowered. So it would keep trying 4 or 5 times before giving up.
The reason the computer was delivering two balls to the shooter lane is that it wasn’t sensing the first ball had actually made it to the shooter lane, so it would try again.
Both of these problems weren’t consistent which led me to the intermittent switch idea. The microswitches were probably dirty and worn inside. Unfortunately, since they are totally enclosed they can’t be easily cleaned. Sometimes I can flush the switches out with contact cleaner, and get them working again. In this case, it worked!