There are several monitors in play throughout WOZ history. In general - and please, guys I know that your particular WOZ is the exception but that’s anecdotal and doesn’t invalidate what I’m going to write here - in general the ECLE green games have either a 110v Wells G or a 110v Happ controls monitor and early standard chrome WOZ have either one depending on the build date. Ruby 75ths came later and by the time they did, the Wells were gone and the Happ 110v were almost gone for the most part. After that there were 2 or 3 12vdc monitors in use and the suppliers changed back and forth during WOZ and then hobbit builds (hobbit 3/2016 and beyond). I believe.a select few early 75ths have 110v AC monitors but they are in Europe not the continental USA. So I’m general 75ths have 12vdc monitors of a couple styles and many standard chromes have 12v panel monitors. Except for YBRs which have the newer cabinet and pivoting monitor, that’s the deal with WOZ games as built.