JLG 120-SXJ ANSI Service Manual - Manual (Page 48)

SECTION 3 - CHASSIS & TURNTABLE
3-20 – JLG Lift – 3121105
Current Regulated Output
This controller output is also current regulated. This con-
troller was designed to output from 20 to 130 milliamps
through a 17 Q coil using a 12 volt supply. Ohms Law dic-
tates that the Current is always equal Voltage divided by
Resistance. If the supply voltage or the coil resistance
should change, Ohms Law dictates that the output current
must also change which will affect the speed of the func-
tion accordingly. Because this controller is equipped with
a current regulated output, it senses a change in voltage
or resistance in the circuit and adjusts the duty cycle of
the PWM signal so that the output current remains a con-
stant current. Because the Current is constant and Resis-
tance is machine dependent, the duty cycle will vary in an
attempt to supply the required level of output. This feature
ensures that the function speed the operator wishes to
select always remains the same, within the limits of Ohms
Law.
Dual Range
This controller is capable of providing two, independently
adjustable, maximum output ranges with the same
amount of handle travel. The Hi Range would normally be
adjusted for full flow (maximum function speed) of the
valve at full handle travel. The LO Range would provide
some potion of the Hi Range setting, providing reduced oil
flow to the valve, with the handle at full travel. LO Range
provides the operator with excellent control of the propor-
tional function with increased resolution for precise
maneuverability.
Both outputs are linear between the Threshold setting and
their respective setting. The controller is in the Hi Range
mode when 12 volts is applied to the (R) terminal. As a fail
safe, when system voltage is removed from the (R) termi-
nal, the Lo Range feature is active.
I.R.S (Integrated Ramp System)
This controller is calibrated to provide a maximum ramp
time of 2 seconds. This feature limits the rate of change of
the output, eliminating a jerky response associated with
sudden handle movements. Any change in handle posi-
tion will result in a smooth change in function speed. The
2 seconds is measured between the Threshold and Hi or
LO range setting.
R.T.O. (Ramp Thru Off)
This controller is configured with an enhanced ramp fea-
ture that allows the handle to released or moved from one
handle extreme to the other without canceling the ramp
duration. The RTO duration is factory set to 2 seconds.
3.10 CONTROLLER SETUP
NOTE: Power needs turned on and footswitch depressed to
set controls. See Table 3-1, Controller Settings for
Milliamp Settings.
Lift
1. Connect Amp Meter inline between the lift card plug
pin #4 and tan 55-1 wire.
2. Operate Lift Controller just past the off position.
Adjust the threshold trimpot.
3. Fully stroke controller and adjust HI range trimpot.
4. Turn function speed control CCW to snail position.
Fully stroke controller and adjust LO trimpot.
5. Adjust RAMP trimpot to provide a smooth start and
stop function.
Swing
1. Connect an amp meter inline between the swing
card plug pin #4 and white 55-1 wire.
2. Operate swing controller just past the off position
and adjust threshold trimpot.
3. Fully stroke controller and adjust HI range trimpot.
4. Turn function speed control CCW to snail position,
fully stroke controller and adjust the LO trimpot.
5. Adjust RAMP trimpot to provide a smooth start and
stop function.
Figure 3-13. Typical Card Adjustments