Jet J-420, Operating Instructions And Parts Manual

Page: 17 / 36

17
10.0 Troubleshooting
Symptom Possible Cause Correction
Motor will not run Voltage is too low. Check power supply for proper voltage.
Branch circuit fuse is blown or circuit
breaker is tripped. Determine the reason for the blown fuse or
tripped circuit breaker; then replace the fuse
or reset the breaker.
Branch is shut down for service. Check all personnel and machines on
the branch to be certain someone has
not shut down the branch for service. DO
NOT replace the fuse or reset the breaker
unless you are certain no personnel are
working on the machines, wires or controls in
the circuit.
Open circuit in the wiring. Inspect all wire connections for loose or
open connections.
Motor is defective. Replace the motor.
Switch is defective. Replace the switch.
Motor stalls easily Low voltage. Check for proper voltage at the motor;
correct as necessary.
Fuse blown (three phase motors only). Replace the blown fuse.
Improper wiring. Check for proper connections.
Abrasive belt or disc
slows down although
motor keeps running at
working speed Belt is slipping. Replace the belt.
Poor tracking Tracking is out of adjustment. Adjust the belt tracking.
Too much belt tension. Loosen the tension until the belt is just taut.
Not enough belt tension. Tighten the tension until the belt is more taut.
Belt is jointed improperly. Check belt for an irregular seam or shape.
Lack of crown on the drive roller. Remove the belt and put a straight edge
along the drive roller. There should be a
slight crown (high spot toward the middle of
the roller.) If the crown has worn away,
replace the roller.
Worn bearings. Check all the bearings for excessive heat or
loose shafts. Replace if necessary.
Unsteady belt Slack in the abrasive belt Adjust the belt tension.
Short belt life Excessive pressure applied while
grinding. Allow the belt to do the cutting. Excessive
pressure only dulls the grit and removes it
from the cloth.
Working on only one side of the belt or
only in one area of the disc. Use all surface areas of the abrasive cloth.
Incorrect abrasive material or grit size. Check with your abrasives supplier for
recommendations on the type and
coarseness of the abrasive required for the
workpieces you are sanding or grinding.
CAUTION: For all of the electrical faults and corrections in the above table JET recommends the use of a qualified
and licensed electrician for all circuit tracing, diagnosis and repair.