Graco Mark X 249627 Instructions page 32

Electrical
Symptom: Sprayer does not run or stops running
• Plug sprayer into correct voltage, grounded outlet
• Set power switch OFF for 30 seconds and then ON
again. This ensures sprayer is in normal run mode
• Turn pressure control knob clockwise 1/2 turn
• View digital display
DIGITAL CONTROL BOARD
DISPLAY STATUS LIGHT
Blank Never lights
---- bar Blinks once
and stops
32
Relieve pressure;
page 27.
INDICATION
No power to control
.
No RUN command
to control board
.
To avoid electrical shock or moving parts hazards
when covers are removed for troubleshooting, wait
30 seconds after unplugging power cord for stored
electricity to dissipate. Keep clear of electrical and
moving parts during troubleshooting procedures.
• If no digital display is available, use control board
status light to troubleshoot problems: Turn ON/OFF
switch OFF, remove control cover and then turn
power back ON. Observe status light.
WHAT TO DO
1 Verify required voltage is present.
2 Check wiring connections to control board.
3 Perform continuity check on power cord and switch.
Replace power cord or switch as needed.
4 If steps 1 - 3 are ok, replace control board.
1 Make sure prime valve is open and there is no pressure
in the system.
2 Turn pressure control knob clockwise.
3 Check potentiometer connection to control board.
4 Check pressure control knob alignment to potentiometer
shaft. Turn shaft fully clockwise and attach knob in full
ON position.
5 Unplug potentiometer. Short out center pin of control board
potentiometer connector to each outer pin (one at a time).
If sprayer runs, replace potentiometer, page 76.
6 Check transducer connection.
7 Disconnect and reconnect transducer plug to ensure good
connection with control board socket. Check that transducer
contacts are clean.
8 Open prime valve. Connect a known good transducer in
place of the sprayer transducer. Set sprayer ON. Replace
transducer If sprayer runs. Replace control board If sprayer
does not run.
Troubleshooting
311421H