Boom Function Board Diagnostics - Skyjack SJKB-40-D Operating Maintenance Instructions & Part List

BOOM FUNCTION BOARD DIAGNOSTICS

1. Open Platform Control Box and locate the Boom Function Control Board. Refer to Figure 6-2 for location.
2. Pull out the Platform Emergency Stop Button and depress and hold the foot switch.
3. Locate the terminals labeled "Vs" and "GND" on the Boom Function Control Board.
4. Measure the voltage between the terminals labeled "Vs" and "GND". It should read 10-12 volts. If no voltage
present, repair the wiring between the Boom Function Control Board and the Platform Terminal block. If
voltage present, go to step 5.
5. Locate the terminals labeled "+" and "-" on the Boom Function Control Board. Refer to Figure 5-5 for location.
6. Measure the voltage between the terminals labeled "+" and "-". It should read 6.2 volts. If no voltage present
replace the Boom Function Control Board, If voltage present go to step 7.
7. Locate the terminals labeled "-" and "SIG" on the Boom Function Control Board. Refer to Figue 5-5 for location.
8. Attach the Meter leads to the terminals labeled "-" and "SIG".
9. Slowly operate the Speed Knob several times from the fully counterclockwise(left) to the clockwise(right)
position while observing the meter. The reading should vary SMOOTHLY between 3 volts(fully
counterclockwise) to 4.8 volts(fully clockwise). If no voltage present or reading "skips" replace the Speed
Control Potentiometer. If voltage present go to step 10.
10. Locate and remove wire #12 from the terminal labeled "PWM A". Refer to Figure 5-5 for location.
11. Switch the meter to the milliamps function. Attach the Black (-) meter to the terminal labeled "PWM A". Attach
the Red (+) lead to wire #12.
12. Slowly operate the Speed Knob several times from the fully counterclockwise(left) to the fully clockwise(right)
position while observing the meter. The reading should vary SMOOTHLY between 550mA(fully
counterclockwise) to1500 mA(fully clockwise. If no amperage present replace the Control Board. If readings
are outside this range refer to Page 13,"Boom Control Board Adjustment Procedure". If amperage present
refer to Page 5 in Section 4, "No Boom Functions from Platform".
SECTION 5, Page 12
STEP 4
Figure 5-5. Boom Function Board Settings.
STEP 6
STEP 9
JUN. 1999
STEP 11
Ma40-505
SJKB-40-D, SJKB-40-D/F