Response from Jonathan: Ted,
 
Your problem with the power going to your monitor could be due to an issue with your isolation transformer (i.e. it could have gone bad, the input voltage may be low, etc.). Try taking your multimeter and measuring the AC voltage going in to and coming out of the isolation transformer to see what you get. If the input voltage is correct (i.e. around 120 VAC or so) but the output voltage is much lower than that, then you may need to replace the isolation transformer. If the input voltage is low, then you may need to track down where it’s getting it’s AC voltage from. Keep in mind that the input voltage for the isolation transformer in most arcade cabinets comes either directly from the wall plug or from an AC filter that’s in line with the wall plug. If this is not the case in your cabinet, you might consider rewiring it to ensure that it is getting the correct input voltage.
 
Hope that helps. Thank you for your question and good luck with your repair.