Update: Turns out that my unit was bad, They quickly repaired the unit and sent it back.
Now I can read the tms27c020 chip fine. I'm having problems writing the data back on to another chip "AM27C020 1200C" I verify that the chip is blank, It starts to write then gives an error. I tried slower speeds aswell.
Well my repaired Programmer read eproms fine but does not write. I have tried changing the speed and it doesn't fix it. I have tried other computers same problem.
Check the USB current level. It should be at least at level 5 or above. By the way, where you send the programmer and repaired? You may need to contactv them again.