Did you replace the pre-driver transistor?
Do you have a logic probe?
(Topic ID: 271231)
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Firepower
Williams, 1980
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Pull the solenoid fuse so the coil does not energize.
Power up the game and connect your logic probe.
Probe the AND gate that drives the Ball Release solenoid.
IC1 pin 9 is blanking input (should be HI if all is well)
IC1 pin 10 is the input from the PIA and it should be LOW when the solenoid should be off and flicks HI when the solenoid is activated (you can use solenoid test to activate it if you want)
IC1 pin 8 is the output - it should be LOW when the solenoid is off and HI when it is on.
If IC1 pin 8 is reading low, and the coil is still locking on, you have a bad pre-driver transistor or a bad driver transistor or both. (most likely the cause)
If IC1 pin 8 is reading HI when IC1 pin 10 is LOW - IC1 is bad. (less common)
If IC1 pin 10 (PIA input) is locked HI - you have a bad PIA (rare)
You could also test for a wiring problem by removing J11 and seeing if the coil still locks on. If it still locks on with J11 removed, look for short in the wiring between the driver board and the coil (wire pinched, coil terminal shorting to metal, etc)
Quoted from RC_like_the_cola:schwaggs Pins 9 and 10 of IC1 are both pulsing. Pin 8 is high. This is with the solenoid fuse removed. I'm not sure what connector is J11. Thanks for you help. Just got back in front of the machine tonight. Here is my probe for reference. When I say pulse, all 3 lights are on.
[quoted image]
That doesn't sound right. Can you check the AND gate of the next solenoid? Pins 12 and 13 are the inputs and 11 is the output.
Both 9 and 13 should be solid HI when all is working. If they are pulsing, something is very wrong.
Pin 8 being HI will fire that solenoid. Now its just a question of what is causing it to lock HI when it shouldn't. Could be bad IC1 or something further up the line.
Is the 40 pin interboard connector original?
1 week later
Quoted from RC_like_the_cola:40 pin interconnect was replaced by someone I trust regarding board work and I swapped out the IC1 for shits and giggles and it read the same, so I think the problem is elsewhere. I have the game at home now, so I can spend more time on troubleshooting.
did you try replacing the pre-driver?
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