Remove the SUS board that you found the fuse on and see if there are any burned traces. Also check the SUS board next to it. The fuses protect the output but not the input to the board. The traces tend to become fuses !! Burn traces normally mean that thete are shorted components on the board.
I should be so lucky.... I almost never have CNC problems that are so easy to detect. And sure enough, here we go again. The boards that could have defects that relate to this error are the SUS 02, STB 01 and DBE 01 boards. I've replaced all of these boards with identical known good ones from the 100D CD control, and still get the same error and same GL13 "not on" LED light. I also replaced the other SUS board just for the heck of it... no cigar there either. Good voltages at the main transformer that inputs to SUS...getting 48 VAC for input to the 60 VDC section of SUS 02 (should be 49 VAC according to schematic)
This error (381, supply for motor print board X or Y defective) apparently relates to a lack of 60 VDC, but what is really strange is I do get 60 volts between test point TP13 and TP14 (on SUS 02) but do not get any voltage at pins 19 and 20 on the J4 connector (or at 60 volt test points on the backplane board the J4 feeds... voltage testing with J4 still connected to board, btw..done via wire penetration probes)
At this point all I can guess is a wire/cable issue but that would be very odd if so as they all appear pristine. The only other possibilty would be if something in the generator somehow interacts with these boards in the CD control but no indication of that in the electrical schematics. On the theory of a short in X or Y motor I even disconnected the motors and the motor drives and still get the same error.
Speaking of which, it's interesting that someone has replaced the Y axis motor and it has a different drive board than X.... both appear new...apparently the updated motor required a different board design.
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Here's a PDF file that shows the 4 pages of schematics that relate to this error
www.practicalmachinist.com/AgieCD.pdf