Pressure Control Repair - Graco NOVA Repair Manual

Removal
Refer to Fig. 7.
1.
Relieve pressure; page 4.
2. Remove four screws (18) and cover (39).
3. Disconnect at motor control board (35):
D Four motor leads: two yellow, black (+) and
red (–).
D Lead (D) from potentiometer.
D Lead (E) from transducer.
4. Remove five screws (36) and circuit board (35).
Note: Keep a new transducer on hand to use for test.
CAUTION
Do not allow sprayer to develop fluid pressure with-
out transducer installed. Leave drain valve open if
test transducer is used.
LED
BLINKS
SPRAYER OPERATION
Once Sprayer runs
Two times Sprayer shuts down and LED
repeatedly
continues to blink two times
repeatedly
Three times Sprayer shuts down and LED
continues to blink three times
repeatedly
repeatedly
Four times Sprayer shuts down and LED
repeatedly
continues to blink four times
repeatedly
Five times Sprayer shuts down and LED
repeatedly
continues to blink five times
repeatedly

Pressure Control Repair

Motor Control Board
Motor Control Board Diagnostics
Installation
1. Clean pad on rear of motor control board. Apply
small amount of thermal compound 073019 to pad.
2. Fig. 7. Install motor control board (35) with five
screws (36).
3. Connect to motor control board (35):
D Lead (E) to transducer.
D Lead (D) to potentiometer.
D Four motor leads: two yellow, black (+) and
red (–).
4. Bundle and tie all loose wires.
5. Install cover (39) with four screws (18).
1. Remove four screws (18) and cover (39).
See Fig. 7.
2. Turn ON/OFF switch ON.
3. Observe LED operation and reference following
table:
4.
INDICATES
Normal operation
Run away pressure. Pres-
sure greater than 4500 psi
(310 bar, 31 MPa).
Pressure transducer is
faulty or missing
Line voltage is too high
Too much current
Relieve pressure and un-
plug sprayer before servic-
ing control board; page 4.
WHAT TO DO
Do nothing
Replace motor control board.
See preceding Motor control
board removal procedure.
Check transducer connection.
Open drain valve. Substitute
new transducer for transducer
in sprayer. If sprayer runs,
replace transducer.
Check for voltage supply
problems
Check for locked rotor, worn
motor brushes, or shorted
wiring or motor. Repair or
replace failed parts.
824191
13