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Wednesday 30 May 2018 at 10:33
Check with your DMM, I would not be surprised to fine that the Wire is common. Set to V AC and measure voltage between the Yellow/white wire and Yellow wire at the tranny, see if it is 6 or so volts. if it is then the yellow wire is common.
If you look at the 8 ball schematic, it shows a continues c...
Source: http://pinside.com/pinball/forum/topic/transformer-secondary-windings-forming-a-common-neutral#post-4425424