Vestil PST series - Manual (Page 14)

14
TROUBLESHOOTING GUIDE - EHLT, PST
WARNING: Care should be taken to identify all potential hazards and comply with all applicable safety procedures
before beginning troubleshooting or repairs.
CAUTION: Before performing any troubleshooting or repairs, the load must be removed from the platform. Then either
raise the platform and install the maintenance props or fully lower the platform to the floor.
Only qualified individuals trained to understand mechanical devices and their associated electrical and hydraulic
circuits should attempt troubleshooting and repair of this equipment.
Consult the factory for problems at time of installation, or for any problems not addressed in this manual.
* Check the DC notes page for troubleshooting other problems specific to batteries and charges.
PROBLEM
1) Problem unit doesn't run when
"UP" button is pressed.
2) Motor runs, platform doesn't
move. Power unit not noisy.
3) Motor hums or pumps squeals,
but the platform does not move,
or the platform moves only slowly.
4) Platform raises, then drifts down.
5) Spongy or jerky platform
movement.
6) Platform won't lower.
POSSIBLE CAUSE(S)
a) Transformer fuse is blown.
b) No supply voltage.
c) Upper-travel limit switch is
engaged or bad.
d) Bad control transformer.
e) Bad motor relay coil.
f) Battery voltage low (DC units).
a) Motor rotation is wrong (AC-
powered units only).
b) Pump is failing to build pressure.
a) See last paragraph, above.
b) Excess voltage drop to motor, due
to power wire size too small, wire
run too long, or incoming voltage
too low.
c) Motor is "single-phasing".
d) Pressure relief opening at full
pressure.
e) Contamination holding open the
lowering valve or the check valve.
a) See last paragraph, above.
a) Excessive air in the hydraulic
cylinders.
b) Toe guard is actuated.
a) Toe guard switch, or wire, broken.
b) Solenoid coil is bad.
ACTION
a) Test with meter; replace if bad.
b) Test with meter. Check fuses,
breakers, and overloads to
determine the causes.
c) Inspect, test switch. Replace if
bad. Check for 24 VAC; replace if
bad.
d) Test with meter; replace if bad.
e) The green LED on motor relay will
be off, or will turn off when the UP
push-button is pressed.
f) Test with meter. Change battery if
low (is motor relay LED on?)
a) Verify motor runs CW, opposite the
shaft end.
b) Consult factory.
a) Same as above.
b) Check power installation for
adequacy. Check incoming voltage
while motor is running. Correct
problem found.
c) Determine cause of loss of voltage
on one phase; correct.
d) Check for structural damage or
binding of the scissor legs, etc.
check for platform overload
condition.
e) Remove and inspect. Clean per
instructions in this manual.
a) Same as above.
a) Bleed air per procedures described
in this manual.
b) Check for a toe guard extrusion or
rubber corner that is stuck.
Adjust if necessary.
a) Inspect visually, check with
multimeter. Repair as needed.
b) Check with multimeter on
diodecheck function. (Reading for
ohms will not provide an accurate
test of the coil.)