Discharging The Capacitors; Electrical Test Equipment - Yale 524150797 Maintenance Manual

General Maintenance and Diagnostic Data

DISCHARGING THE CAPACITORS

When working with the electrical systems of the truck,
it is necessary to discharge the internal or external ca-
pacitors of the controllers associated with each circuit
affected.
WARNING
DO NOT make repairs or adjustments unless you
have been properly trained and authorized to do
so. Improper repairs and adjustments can create
dangerous operating conditions. DO NOT operate
a lift truck that needs repairs. Report the need for
repairs to your supervisor immediately. If repair is
necessary, attach a DO NOT OPERATE tag to the
control handle and disconnect the battery.
Disconnect the battery and discharge the internal
or external capacitors before opening any com-
partment covers or inspecting or repairing the
electrical system. DO NOT place tools on top of
the battery. If a tool causes a short circuit, the
high current flow from the battery can cause per-
sonal injury or property damage.
Some checks and adjustments are performed with
the battery connected. DO NOT connect the bat-
tery until the procedure instructs you to do so.
Never wear jewelry or other metallic items on your
fingers, arms, or neck when working near electri-
cal components. Metal items can accidentally
make an electrical connection and cause injury.
Before performing any tests or adjustments, block
the lift truck to prevent unexpected movement.
The capacitors in the transistor controllers can
hold an electrical charge after the battery is dis-
connected. To prevent an electrical shock and
personal injury, discharge the internal or external
capacitors before inspecting or repairing any
component in the electrical compartments. Make
certain that the battery has been disconnected.
DO NOT short across the motor controller termi-
nals with a screwdriver or jumper wire.
Check the Service Manual section in Yale Axcess Online for possible updates and check pertinent Bulletins
9030-03-2
CAUTION
To avoid controller damage, always disconnect
the battery, discharge the internal or external ca-
pacitors, and never put power to the controller
while any power wires are disconnected. Never
short any controller terminal or motor terminal to
the battery. Make sure to use proper procedure
when servicing the controller.
1. Move the lift truck to a safe, level area and com-
pletely lower the forks. Turn the key switch to the
OFF position and attach a DO NOT OPERATE
tag to the control handle. Block the drive wheel to
prevent unexpected movement.
2. Disconnect the battery power cable connector
from the truck connector located on the top-left
side of the frame. Pull the battery cable connector
handle to separate the battery connector from the
truck connector.
3. Remove the operator compartment cover.
4. Discharge the internal or external capacitors in
the controllers by connecting a 200-ohm, 2-watt
resistor across the controller B(+) and B(-) termi-
nals of the combination controller. Remove the re-
sistor after discharging the capacitors. See Fig-
ure 9030-03-1.

ELECTRICAL TEST EQUIPMENT

Before beginning intrusive circuit checks, verify the
vehicle battery state of charge. Visually inspect sus-
pected connectors for loose, damaged, or corroded
terminals. Check for blown fuses and inspect circuits
for cause of overcurrent conditions. Physically check
mechanical operation to ensure a switch, relay, or sol-
enoid is not sticking or damaged.
NOTE: Measuring continuity between two terminals
of a switch while operating the switch will determine
its functionality.
ELECTRICAL SYSTEM