I have a ColorSync 20" which basically works but is dark (I can't adjust the brightness up further than it is), and which has some sort of failed adb-related circuitry (though replacing the adb board in the bottom with a known-good one did not solve the problem, so the problem seems to be higher up in the unit), which means that it isn't recognized as a ColorSync! It does, however, work just fine under OSX, where even the brightness is OK, and where the adb system is entirely by-passed.
I also have a ColorSync 17", and it is the more troubled of the two. The focus/ convergence (not sure which is giving the trouble, but probably focus) can be set right, and then 30 mins later it's off again.
I know where there's a ready local supply for more of these units, so if I were comfortable working in the high voltage areas, I might get some others as replacements and keep these for parts, but it's too dangerous, methinks, to fiddle around in there among those wires and such. So, having been twice smitten and bitten, no more Apple ColorSync monitors for me. They may have been the high end, but they seem to me to be lemons.