LW3 coil issues

drwicket

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So I have 2 of my upper pop bumpers and the left slingshot bumper are firing but not very well. All of them are very week. I tested everything on the cpu board and everything is good. I used the alligator clips / wire and hooked it to a ground and tested each coil and every coil fired just fine.

I have been told that it might be a grounding issue but have no idea how to fix it.

Any ideas? Or am I completely wrong on my diagnosis?
 
Barring an adjustment problem like Grbgemen stated, or some wiring problem, try and look at the grounding at CN19.

Since they are getting power and firing okay when grounded, I think that takes the red wire out of the problem list.

It also sounds like the transistors are okay. If you don't find a ground problem, looking at the special coils diagram on Page 47 of the manual, those three coils are controlled by transistors Q8, Q9, and Q10. According to Pinrepair, all three of those transistors connect to chip 12A, chip 11C, and then to a PIA.

Since these chips are common to all three coils, I'd wonder about a problem with one of them. It seems kind of weird that three individual components would fail for each individual coil at the same time, and more likely that one component would fail that affects all three. That being said, I could be way off base and completely wrong. :)

If you have a manual, CPU Sheet 3 (Page 53) is the page with all this on it.
 
Last edited:
I edited my earlier post to correct some mistakes, so make sure to double check it depending on when you read it.
 
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