Pulled a rookie move. Mixed black & white molex on Williams System 4

TheDrewster

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Pulled a rookie move. Mixed black & white molex on Williams System 4

I have owned several System 3-6 machines in the past, and for whatever reason, I had a complete brain lapse this time. I picked up a Flash a couple days ago and it was working until my dumb ass switched the two black and white molex connectors leading from the playfield to the backbox.

Now everything I have read tells me I have truly screwed the pooch in terms of now having to repair the PCBs. I am willing to swallow my pride and accept that fact. However, one thing to note is that I never actually started any games, so technically, no solenoids were activated while the connectors were backwards. My question is, did I still cause damage to the PCBs even if no games were successfully played? Or was the damage already done when I booted the machine?

FWIW, I am almost done kicking myself. A few more kicks ought to do it.
 
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I accidentally did that with my Hyperball, didnt damage the MPU, maybe caused a few issues with the driver board but its all working now. That was a long time ago.. And i dont know what difference a Hyperball would be compared to other system 7 games except Hyperball only has one coil and thats the cannon.
 
However, one thing to note is that I never actually started any games, so technically, no solenoids were activated while the connectors were backwards. My question is, did I still cause damage to the PCBs even if no games were successfully played? Or was the damage already done when I booted the machine?

What you don't realize is that "the game didn't start so no solenoids were activated" is only how the game works when it's plugged in properly. You aren't accounting for the multitude of wires where the solenoid or other voltage is constantly flowing now (because the switches came after the plug in the chain) being hardwired to other inputs instead of flowing through to the right places and through switches that limit them. Those switches aren't controlling the voltage (obviously) when it's not plugged in correctly and constant voltage is flowing to places that are willingly ready to accept it also always and blow stuff up. As such, it's irrelevant if anything was activated or not as it doesn't make a difference. Yes, there are wires that will be dead until the solenoids are activated, but not all of them, and I think Williams games switch ground anyways and provide a constant flow of voltage to solenoids which unfortunately is worse for your case, but don't quote me on that.

Luckily I think when this happens there's a few parts "first in line" that will blow up and coincidentally prevent things further down the line from blowing up. It's all about figuring how far it got, as it's a bit of a shit shoot on what will blow and what won't, or where it'll stop due to the differences in components and randomness.
 
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if you have an extra driver board system 3 through 7 that you think is good plug it in and see what it does...

your mpu board is probably still okay, issues You are having now seem to be driver board related
 
I took all the boards out, reflowed all the solder joints, and replaced a couple popped fuses. After putting everything back together, I was amazed to discover that everything still works, minus one shorted TIP42 in the lamp column at Q65. I don't know how I escaped with that being the only issue, but I am considering this one big lesson learned, and one huge bullet dodged. Jeez.
 
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