CAUTION
To avoid controller damage:
1. ALWAYS disconnect the battery when serv-
icing the controllers.
2. ALWAYS discharge the capacitors using
the proper procedure before performing
any service.
3. NEVER put power to the controller with any
power wire disconnected or loose.
4. NEVER short any controller terminal or mo-
tor terminal to battery (+), battery (-), or the
frame.
CAUTION
Correct meter polarity is necessary for some
checks. Meter correct positive is indicated as (+).
Meter correct negative is indicated as (-).
NOTE:
Use a digital meter with a minimum rating
of 20,000 ohms per volt to make accurate measure-
ments.
1.
To avoid injury and prevent electrical shock,
perform the following steps (Step 2 through
Step 7 below) to discharge the capacitors before
troubleshooting, making adjustments or re-
pairs, or connecting or disconnecting a PC serv-
ice tool:
2.
Turn the key switch to the OFF position and
DISCONNECT THE BATTERY.
3.
Block the aerial work platform so the drive
wheels are off the floor to prevent aerial work
platform from moving.
4.
Remove the electrical compartment cover to ac-
cess the combination and traction controller.
See the Frame manual listed in the General
section of this manual for procedures.
NOTE:
The combination and traction controllers
are wired parallel. Connecting the resistor across
the combination controller will also discharge ca-
pacitors in the traction controller if they are prop-
erly connected.
5.
Discharge the capacitors in the controllers by
connecting a 200-ohm, 2-watt resistor across
the lift controller’s negative (B−) and positive
(B+) terminals. Wait at least 20 seconds to be
sure that the capacitors are fully discharged.
See Figure 2.
6.
If necessary to discharge the traction controller
separately from the combination controller, per-
form Step 5. See Figure 3.
7.
Remove the resistor from the controller(s) and
reinstall the covers (see the Frame manual lis-
ted in the General section of this manual for
procedures) before returning the aerial work
platform to service.
1. B- TERMINAL
2. JUMPER LEADS
3. 200-OHM, 2-WATT RESISTOR
4. B+ TERMINAL
Figure 2. Combination Controller
4000 SRM 1916
Special Precautions
3
