If the unit has information printed on it listing the manufacturer and model number, that's where I would start. I would contact the mfg regarding specifications for this unit, because most mfg's of these things make them in a wide variety of resolutions (lines per cm/inch), which is likely coded into the part number. Also, they will be able to tell you info regarding proper electrical connections. These days, the mfg probably has info on it available on the web, unless it's a really old device (which they will still be likely to give you by phone).
JB