Zenith Data Systems laptop

Just purchased three Zenith Data Systems laptops at a Hamfest - my first IBM-compatible computers, believe it or not (always focused on the Apples & under-the-TV 8-bit systems). Needless to say, I don't know a thing about them. There are no power adapters. I have a 12v 300 mA adapter. Will that work with them? I hooked it up to all three systems - 2 of them didn't do a thing. The third "spins" up and I can hear a very faint wining noise from inside. The monitor, however, shows nothing (could this be due to too little amperage?). The computer gives a three-tone beep every 15 seconds or so (estimate) and beeps whenever I press a key. Anybody have any suggestions? Like I said, I don't anything about these, so any advice would be appreciated. Thanks, Tom -- Sysop of Caesarville Online Client software at: <http://home.earthlink.net/~tomowad/>