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Sunday 27 May 2018 at 11:23
Voltage is a bit lower on Williams then on a Gottlieb (24 V) you can increase by using the high tap on a Williams transformer.
Don't if it will be enough, but it will work.
Source: http://pinside.com/pinball/forum/topic/are-wms-and-gottlieb-power-supplies-interchangeable#post-4420824