Vestil EHLT, PST - Manual (Page 18)

02/06 24-126-120
V ESTIL M FG . C O . 18
T ROUBLESHOOTING G UIDE -- EHLT (1-4K) & PST (1-3K)
¾ WARNING: Care should be taken to identify all potential hazards and comply with all applicable safety procedures
before beginning troubleshooting or repairs. Disconnect or disable all energy sources utilizing proper lock-
out/tag-out procedures.
¾ 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.
¾ Only qualified individuals trained to understand mechanical devices and their associated electrical and hydraulic
circuits, along with the hazards that could result from them, should attempt troubleshooting and repair of this
equipment.
Consult the factory for any problems not addressed in this manual.
* Check the DC notes page for troubleshooting other problems specific to batteries and chargers.
Problem: Possible cause(s): Action:
Power unit doesn’t run when “UP”
button is pressed.
Transformer fuse is blown.
No supply voltage.
Upper-travel limit switch is engaged or bad.
Bad control transformer.
Bad motor relay coil.
Bad solenoid start switch (DC units).
Battery voltage low (DC units). Test with meter; replace if bad.
Test with meter. Check fuses, breakers,
and overloads to determine the cause.
Inspect , test switch. Replace if bad.
Check for 24 VAC; replace if bad.
Test with meter; replace if bad.
The green LED on motor relay will be off,
or will turn off when the UP pushbutton is
pressed.
Test with meter. Charge battery if low (is
motor relay LED on?)
Motor runs, platform doesn’t move.
Power unit not noisy.
Motor rotation is wrong (AC-powered units
only).
Pump is failing to build pressure.
Verify the motor runs CW, opposite the
shaft end.
Consult factory.
Motor hums or pump squeals, but the
platform does not move, or the
platform moves only slowly.
See last paragraph, above.
Excess voltage drop to motor, due to power
wire size too small, wire run to long, or
incoming voltage too low.
Motor is “single-phasing”.
Pressure relief opening at full pressure.
Contamination holding open the lowering
valve or the check valve.
Same as above.
Check power installation for adequacy.
Check incoming voltage while motor is
running. Correct problem found.
Determine cause of loss of voltage on
one phase; correct.
Check for structural damage or binding
of the scissor legs, etc.
Check for platform overload condition.
Remove and inspect. Clean per
instructions in “Power Unit Operation.”
Platform raises, then drifts down. See last paragraph, above. Same as above.
Spongy or jerky platform movement. Excessive air in the hydraulic cylinders. Bleed air per procedure described in
“Power Unit Operation.”
Platform won’t lower. Toe guard is actuated.
Toe guard switch, or wire, broken.
Solenoid coil is bad.
Physical blockage of the structure.
Solenoid valve, flow control, or suction
hose screen plugged.
Check for a toe guard extrusion or rubber
corner that is stuck.
Adjust if necessary.
Inspect visually, check with mutimeter.
Repair as needed.
Check with multimeter on diode-check
function. (Reading for ohms will not
provide an accurate test of the coil.)
Inspect for foreign material or objects
that might block the leg set or its
rollers.
Remove and inspect. Clean per
instructions in “Power Unit Operation.”
Platform lowers too slowly. Pinched hose.
Velocity fuse locking (platform only slowly
creeps down).
Flow control spool sticking.
Check pressure, supply, and return
hoses for kinks.
Same as for jerky platform movement.
Remove plug from FC port; push on flow
spool to ensure it is fully pressed into
the cavity. Pull and clean the spool if
necessary.
Platform lowers too quickly. See last paragraph, above. Same as above.