If fuse holds with one of those plugs removed, might help some in locating. Power supply board J101 and 102 come from the power transformer with 17 and 7 volt AC on 101 and 16 volt AC on 102. Easiest to find things would be power supply board or backlight board - maybe shorted electrolytic capacitor or voltage regulator IC. Discrete components are in the power supply board, the backlight board, and some of the audio boards. Looking at the manual, most all of the synth section and logic section boards are largely large scale ICs. However, there are some manuals floating around on the Internet, probably from one of the Yahoo Kurzweil forums (I don't remember where). If you do have some electronics skills and test equipment: Kurzweil does not release service manuals.
If there is nothing visible, it is time to carry it to a good tech.
Look carefully at all the inter-board wiring (when Kurzweils are buttoned up, there is wiring that passes between metal parts, and can get squeezed and short out). If the replacement fuse blew, there is something shorted somewhere.
