Tormach PCNC 770 - Page 200

Chapter 10
200
UM10350_PCNC770_Manual_0916A
Troubleshooting
Axes Drive Subsystem Checklist
Table 4.7
Testing limit switch problems
Diagnostic Screen Inputs
Status Reported
Test to Perform on Wiring
at the Control Board
Results and Conclusions
X limit and home light is always
on even though the switch is not
actuated
Jumper J2-1 to J2-4 at the
control board.
If the light does not go out when
the terminals are jumped, the
control board is defective. If the
light goes out when the terminals
are jumped, the wiring has a break
or the limit switch is defective.
Power off the mill, disconnect
wires from the switch and tie the
two wires together and tape over
to prevent short circuits. Power
on. If the diagnostic light is off,
the wiring is OK and the switch
is defective. If the diagnostic light
is on, the wiring has a break or
defective connection.
Y limit and home light is always
on even though the switch is not
actuated
Jumper J2-2 to J2-4 at the
control board.
Z limit and home light is always
on even though neither the up or
down limit switch is not actuated
Jumper J2-3 to J2-4 at the control
board.
X limit and home light is never on
even though the switch
is actuated
Remove wire J2-1 at the
control board.
If the light does not go on when
the wire is removed, the control
board is defective. If the light goes
on when wire is removed, the
wiring has a short or the limit
switch is defective. Power off the
mill, disconnect wires from the
switch and tape the end of each
wire to prevent shorts. Power on.
If the diagnostic light is on, the
wiring is OK and the switch is
defective. If the diagnostic light is
off, the wiring has a short circuit.
Y limit and home light is never on
even though the switch
is actuated
Remove wire J2-2 at the
control board.
Z limit and home light is never on
even though either the up or down
limit switch is actuated
Remove wire J2-3 at the
control board.
NOTE: Oen mes a defecve switch can be cleaned with compressed air and sprayed with WD-40® to x
a problem.
NOTE: If the stainless steel bed pan does not sit ght against the front edge of the mill bed, coolant and
chips are allowed to converge on the X-limit switch. Using butyl tape or silicone sealer between the pan
and bed will prevent this from occurring.