Operation - Graco GMax
3900 Instruction Manual

1.
Relieve pressure; page 4.
2. Fig. 15. Remove five screws (307) and
cover (322).
3. Disconnect lead (E) from control board (302).
4. Remove three screws (319) and fluid filter (318)
from control plate (301). Carefully pull transducer
connector through rubber grommet (315).
1.
Relieve pressure; page 4.
2. Fig. 15. Remove five screws (307) and
cover (322).
3. Disconnect lead (D) from control board (302).
4. Loosen set screws on potentiometer knob (313)
and remove knob, shaft nut, lockwasher (310) and
pressure adjust potentiometer (310).
5. Remove seal (311) from potentiometer (310).
1. Fig. 15. Remove five screws (307) and
cover (322).
2. Start sprayer.
LED SPRAYER OPERATION
BLINKS
Two times Sprayer shuts down and LED contin-
repeatedly
ues to blink two times repeatedly
Three Sprayer shuts down and LED contin-
times re-
ues to blink three times repeatedly
peatedly
Four times Sprayer shuts down and LED contin-
repeatedly
ues to blink four times repeatedly
Five times Sprayer shuts down and LED contin-
repeatedly
ues to blink five times repeatedly
Six times Sprayer shuts down and LED contin-
repeatedly
ues to blink six times repeatedly
Pressure Control Transducer
5. Remove pressure control transducer (318z) and
1. Fig. 15. Install packing o-ring (318aa) and pres-
2. Carefully feed transducer connector through
3. Connect lead (E) to motor control board (302).
4. Install cover (322) with five screws (307).
Pressure Adjust Potentiometer
1. Install seal (311) on potentiometer (310).
2. Fig. 15. Install pressure adjust potentiometer
3. Connect lead (D) to control board (302).
4. Install cover (322) with five screws (307).
Control Board Diagnostics
3. Turn ON/OFF switch ON.
4. Observe LED operation and reference following
INDICATES
Run away pressure.
Pressure greater than
4500 psi (310 bar, 31
MPa).
Pressure transducer is
faulty or missing
Generator voltage is
low
High clutch current
High clutch temperature Replace clutch armature and rotor
packing o-ring (318aa) from filter housing (318a).
sure control transducer (318z) in filter
housing (318a). Torque to 30–35 ft-lb.
rubber grommet (315). Install fluid filter (318) on
control plate (301) with three screws (319).
(310), shaft nut, lockwasher (310) and potentiome-
ter knob (313).
a. Turn potentiometer shaft (310) clockwise to
internal stop. Assemble potentiometer knob
(313) to strike pin on plate (312) and have
bottom of knob clear plate by .040 to .060 in.
b. After adjustment of step a., tighten both set
screws in knob 1/4 to 3/8 turn after contact
with shaft.
table:
WHAT TO DO
1. Check pressure transducer con-
nection at control board
2. Replace pressure transducer
3. Replace control board
1. Check pressure transducer con-
nection at control board
2. Replace pressure transducer
3. Replace control board
1. Increase engine throttle
2. Check wiring connections
3. Service Honda engine alternator
1. Check clutch 5-pin bulkhead con-
nector. Clean contacts.
2. Measure 1.2
(GMax3900); 1.7
5900) across clutch field at 70 F
3. Replace clutch field assembly
0.2Ω
0.2Ω (GMax