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Williams bumpers

HomerRamone

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As per my other thread - I have a stuck on bumper. I've ordered a replacement transistor (FQP13N10L) thinking its possibly that... But until it arrives im exploring other possibilities.
(And wanting a better understanding of how it all works)

I gather that the bumper can be fired 2 ways.
1 is by the MPU saying "Trigger the bumper" as it does in diagnostic mode for example.
1 is when the switch that's closed by the ball rolling over the bumper deely at the bottom of the bumper is closed
Also from what ive read there are 2 switches underneath.
One is to trigger the solenoid as per above, and the other is closed when the solenoid fires and the thing actuator thing hits it and awards the score.
Presumably if the transistor is dead it mean its always going to think the MPU wants the solenoid on - so thats the most likely cuplrit ?

How is the switch wired to fire the solenoid - does it just a signal back to the MPU which then triggers it or is it wired directly ? (Probably sounds like a stupid question ... certainly will when you know the answer :D )
 

Andy_B

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Think of the transistor as a switch that (when instructed ultimately by the MPU) grounds the coil momentarily allowing current to flow and the coil to fire.

If the transistor has failed the "switch" is always on so the coil is permanently energized. Here endeth the fuse.


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AlanJ

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the “special solenoid circuit” in those williams games is dumb. ie there is no mpu involved. i.e. the switch directly activates the transistor circuit to energise the coil. if that switch gets stuck then the coil is on all the time = damage. the second part is the switch which is then part of the switch matrix and let’s the cpu know so it can score points etc.

williams thought the mpu / switch matrix wouldn’t be fast enough for pops and slings, hence this direct way of working.
 
OP
HomerRamone

HomerRamone

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If the transistor has failed the "switch" is always on so the coil is permanently energized. Here endeth the fuse.
Ive no doubt at all this is how the fuse died. Just trying to figure out what the cause is - as in what I should check if the transistor is fine :)

the “special solenoid circuit” in those williams games is dumb. ie there is no mpu involved. i.e. the switch directly activates the transistor circuit to energise the coil. if that switch gets stuck then the coil is on all the time = damage. the second part is the switch which is then part of the switch matrix and let’s the cpu know so it can score points etc.

williams thought the mpu / switch matrix wouldn’t be fast enough for pops and slings, hence this direct way of working.
So the switch feeds right back to the board and activates the transistor I guess ?

I probably is just the transistor but im somewhat of a pessimist and impatient so im just wanting to know where to look :)

Thanks folks !
 
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HomerRamone

HomerRamone

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Cosmic yeah. I checked the resistor but cant check the cap. (Not sure if I have one lying around to change anyway - cant hurt)
 
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HomerRamone

HomerRamone

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Clearly this forum has voodoo powers. It stopped locking on again now... not sure whether to be happy or concerned :D

Hanx for all the pointers anyway folks. More knowledge if nothing else (and some spare transistors which will arrive tomorrow mean it'll probly be ok for the foreseeable :D
 

Jay Walker

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Apr 19, 2013
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The 'special' switch of a bumper or slingshot switches to ground, pulling one input of a 'Not Or' (NoR) gate (there are 4 gates in a 7402 chip) Low. It's the gate output that switches the pre-driver/driver/coil.
 
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