Power supply dead?

I've got one of them TI Silent 700 Model 703 portable data terminals. The external power supply that comes with it is 20VAC. It's got three conductors on the connector. I can't get any voltage out of it. Is it dead? Or is it that it needs to sense a loop or something across all pins before it starts emitting juice? Not likely, I'm sure, but I thought I'd ask before I start tearing this apart to see if it has an internal fuse. Any ideas? Thanks! -- Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org [ Old computing resources for business || Buy/Sell/Trade Vintage Computers ] [ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]