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Generally when counting a bonus score at the end of the ball the number of points added is determined by the rate at which the 1000 point relay is fired relative to rate at which the Bonus Unit steps down towards zero. When counting a single bonus the 1000 point relay is fired once for each Bonus Unit step. When counting a double bonus, the 1000 point relay is fired twice per Bonus Unit step. In Hang Glider the circuit looks like this:
Hang Glider bonus count (resized).jpg
On a single bonus the 1000 point relay gets five pulses per Score Motor cycle (or 180 turn of the motor), four pulses come from a switch on the #9 Score Motor cam (9A SCM) and a fifth pulse from a switch on the #5 cam (5C SCM). (Note the arrows connecting the circuits together without an explicit wire drawn.) At the same time, the Bonus Unit Reset Solenoid gets five pulses per Score Motor cycle from a switch on the #2 cam (2B SCM). The result is 1000 points per Bonus Unit step.

On a double bonus the circuit gets reconfigured because the Double Bonus relay should fire and change the two Make/Break switches. In this case, the 1000 point relay gets four pulses per motor cycle from the Score Motor 9A switch only and the Bonus Unit Reset Solenoid gets just two pulses, from the 5C and 8C Score Motor switches. The result is 2000 points per Bonus Unit step. Notice on the Score Motor chart how the pulses to the Bonus Unit (from the 5 and 8 cams) happen between the pulses to the 1000 point relay (from the 9 cam).

If your Double Bonus light comes on that indicates that the Double Bonus relay has fired. If that's the case the issue is probably with the Make/Break switch in the red box. The normally closed half of that switch may not be opening and allowing the five pulses from the Motor 2B switch to get through when they shouldn't.

/Mark

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