I've got a dreaded broken hand question. I just picked up a JM the other day and right away the hand was disabled. I enabled it and started the testing, when doing self test it only moves right/left about half an inch a few times on the x-axis and no y-axis movement at all and gives up.
So far I have:
replaced both x and y nuts
made sure both rods can move by hand
checked that all optos, home switches, and ball in hand switch all register manually during switch edge testing
re-soldered all joints on the relay board
used a 12v battery at each motor plug from the relay board to make sure there is no short in wiring and that they move easily
Measured voltage at the y-motor during self test and noticed its getting 2.5v and not moving the motor, so a lot less than the needed 12v
Grounded J126-8 and found that the y-motor was moving super super slow and then an electrical burning smell was coming from the relay board
So I think I isolated it to a relay board issue and the motor only getting a few volts and not the 12v needed for the self test. Would anyone know which component on the board might cause this? and might smell like electrical burn when powered? Any ideas are appreciated, trying to avoid buying a new board altogether.
UPDATE: turns out it was the TIP102 transistor on the relay board for the y-motor