WOW - That 3D illustration - The sense of depth is unreal - I wanted to reach out & plug it in (thanks for spending time doing that), pity it's wrong answer.
The diagram you showed is for the connector that plugs in the playfield & not into the rectifier board. As I say/write (same feces as before) the schematics are for a 1979 SI. The SI machines were a production run, in that run (my SI 09770 is within that run - obviously) there were factory mods done (on assumption) due to field technical issues being reported from customers. So my SI has a third or fourth generation Reg/Rec board which has TEN pin spots as previously listed which is ONE more than ele/sch. diagram from machine ooooo1. I have the original manual, but no schematics.
The concepts not hard is it Quench. Below I've listed bits of your mail & my immediate English thoughts-
"Sounds like a driver transistor is shorted and locking the coil on. A coil is just a length of wire, it isn't going to make much (or any) difference in this manner. The wrong coil certainly won't just burn up."
Yes one coil + one driver on board burned, replaced both.
(message to admin - if this thread was unarchived I wouldn't need to be writing this feces again. Also Quench might answer a question correctly LOL)
"Please go back to basics and learn some things you will HAVE to understand or you are in for a world of pain." I do understand.
"Each coil will have a diode across it - this MUST be connected to the correct wire and sometimes the diode will be installed a different direction on the coil so you MUST look and KNOW which wire to connect." Know this already, thanks.
"SI has additional GI lamps being a wide body machine so the extra pin is likely for those extra lamps - I wouldn't worry too much about that stuff right now, it is unlikely to be causing your issues." Errrr no. Isn't true.
"Do yourself a HUGE favor and spend some time reading ALL THE WAY THROUGH the PinWiki on Bally SS machines. A lot of stuff will come to you if you read this information that has been painstakingly put together by lots of people 'in the know'." read & understood. @ this point in time quench please don't consider yourself "In The Know".
"If you can't be bothered to study up on this then just pay someone to come and look at the machine because, while many things might be straightforward, many are not! IN fact, changing coils and not knowing EXACTLY what you are doing may well have damaged the driver board in this instance." Above describes about driver board, here in the U.K pinball isn't a big thing so mobile technicians are a bit like rocking Horse feces. Thanks for the suggestion, NOT.
I think Quench that covers it.
Any help full replies, please bring-em on (is your user name what everyone does when you come into view).
Ta
Jon