Pressure Control Switch Diagnostics; Pump Diagnostics - Graco magnum pro plus a20 Repair Manual

Pressure Control Switch Diagnostics

Pressure Control Switch
Diagnostics
1. Unplug power cord and Relieve Pressure. See
Pressure Relief Procedure, page 13.
2. If paint is leaking from pressure control switch
between pressure control knob and base, replace
pressure control switch.
3. A60: Remove front cover, yoke, and pins.
Disconnect pressure control switch connector from
control board.
A20, A30, and A45: Remove enclosure and
disconnect pressure control switch connector from
control board. Use finger to support control board
when removing pressure control switch connector.
4. Use ohmmeter to check for no continuity between
sprayer ground and both pressure control terminals
in connector. If either pressure control switch lead is
shorted to ground, pressure control switch wires
have been pinched to ground during assembly and
pressure control switch needs to be replaced.
5. Use ohmmeter to measure across two terminals in
pressure control connector. No continuity should
exist when pressure control knob is at lowest
pressure setting (full counter-clockwise). Replace
pressure control switch if continuity exists.
6. Use ohmmeter to measure across two terminals in
pressure control connector. Continuity or closed
circuit should exist when pressure control knob is
set at maximum pressure (full clockwise). Replace
pressure control switch if no continuity exists.
28

Pump Diagnostics

When repairing or cleaning the pump, never submerge
pump in water or allow fluid to enter pressure control.
When pump packings wear, paint begins to leak down
the outside of the pump. At the first sign of leakage,
replace the pump or additional damage to the drive train
could occur.
1. A20, A30, A45: Replace pump using Pump
Replacement (Complete). See List of Kits, page
30.
A60: Replace pump using Pump Repair Kit. See
List of Kits, page 30.
2. If there is no paint leakage (see Advanced Trou-
bleshooting, page 20). Pump may not be defective.
NOTICE
332697C