Mec 3072RT, Service Manual

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March 2008 "3072RT / 3772RT / 3772RT HD" Service & Parts Manual - ANSI Specifications
Page 4-4
PROBLEM PROBABLE CAUSE REMEDY/SOLUTION
No operation from upper or
Upper Control station Main battery switch turned off
Emergency switch pushed in or Ignition switch
turned off
Dead Battery
Blown fuse
Circuit breaker tripped
Damaged Upper Controls box harness
Failed 25 AMP diode
Failed Power Relay on Circuit board
Located left of Lower Controls box
Upper or lower Emergency Stop switch will cut all power as will
the Ignition switch in the Platform Controls box
Charge battery
Sealed unit just below Lower Controls box
Reset - Located in Lower Controls box panel
Inspect from harness plug to terminal strip under platform
Test/replace. Located inside Lower Controls box
Replace circuit board in Lower Controls box
General Power Issue
Functions from Upper
Controls but not from Upper
Controls Faulty relay, located in Upper Controls box
Interlock switch (Joystick)
Check power on wire 101 from Key switch
Check power on wire 101A from relay to Joystick plug
Check power to RED wire (power to switch) and power to
PURPLE wire (power out of switch) at Joystick plug
Lift/Lower
Platform will not Raise Excessive weight on Platform
Lift Relief valve out of adjustment
Lift Valve SV-1 not energized
Lowering valve SV-5 stuck open
(located at base of lift cylinder CYL-1)
Level Sensor out of level
(platform elevated above 6')
Main system pressure inadequate
Proportional control out of adjustment
(High Range Adjustment)
Maintenance Lock in maintenance position
Lowering valve not energized
Lowering valve not shifting
Lowering orifice (ORF-3) plugged
Down valve on one cylinder inoperative
E-Down cable broken or frayed (3072)
Lowering valve not shifting
Lowering orifice (ORF-3) plugged
E-Down battery discharged
Valve coil failed on either cylinder
Down valve on one cylinder inoperative
Platform will not lower or
lowers slowly
Lowers but not completely
(3772RT only)
Emergency lowering not
working
3772RT ONLY
Lowers but not completely
Reduce weight to within platform capacity
Adjust relief valve to rated capacity
Check lift circuit from Upper Controls box to SV-1 valve
Check and remove contamination, E-Down cable damaged or
replace valve
Reposition machine to firm level surface,
Check Level Sensor function
Check pump output pressure (see Hydraulic Pump Adjustment
in this section)
See section on
Proportional Controller Adjustment in this
section
Return Maintenance Lock to the stowed position
Check lowering circuit from Upper Controls box to Lowering
valve SV-5
Clean debris, replace
Clean orifice
Check valve coils
Replace E-Down cable
Clean debris, replace
Clean orifice
Charge, check charge diode & connections
Test, replace
Check valve coils, wiring
continued…