Electrical Tests; Test Gun Resistance; Test Power Supply Resistance - Graco PRO AA5500sc unicarb Instruction Manual

The performance and safety of the spray gun are
directly affected by the condition of the electrical
components contained inside the gun. The electrical
tests below can be used to determine the condition of
the power supply (27) and the barrel resistor cartridge
as well as the continuity of the electrical path between
the components.
CAUTION
The barrel resistor cartridge is part of the barrel and
is not replaceable. Refer to page 33. To avoid
destroying the gun barrel, do not attempt to remove
the barrel resistor cartridge.
Flush the gun fluid passages with solvent and air. To
get an accurate reading, the fluid hose must not have
any fluid in it.
Use megohmmeter P/N 218979 (L) and an applied
voltage of 500 volts to complete these electrical tests.
Connect the leads as shown.
WARNING
FIRE, EXPLOSION, AND
ELECTRIC SHOCK HAZARD
Megohmmeter P/N 218979 is not ap-
proved for use in a hazardous area. To
reduce the risk of sparking, do not use
the megohmmeter to do electrical tests
unless:
D The gun has been removed from the
hazardous area (see page 31 to re-
move gun);
D Or all spraying devices in the hazardous area
are turned off, ventilation fans in the hazardous
area are operating, and there are no flammable
vapors in the area (such as open solvent con-
tainers or fumes from spraying).
Failure to follow this warning could cause fire,
explosion, electric shock and result in serious injury
and property damage.
Test Gun Resistance (See Fig. 25)
Install the spray tip, air cap, tip guard, and retaining
ring on the gun. Measure the resistance between the
end of the electrode (15a) and the gun body (29) or
turbine air inlet fitting (refer to page 6). The resistance
should be between 329 to 401 megohms. If the resis-
tance is outside the specified range, go to the next

Electrical Tests

test. If the resistance is correct, resume spraying or
refer to Electrical Troubleshooting on page 28 for
other possible causes of poor performance, or contact
the nearest authorized service agency.
Test Power Supply Resistance (See Fig. 26)
Remove the power supply (27) from the gun body (29)
as instructed on page 40.
Measure the resistance from the power supply's
ground contact point (R) to the contact inside of the
power supply seal (27d) [the conductive rubber contact
may be slightly recessed into the seal].
The resistance should be 297 to 363 megohms. If the
resistance is outside the specified range, the power
supply is defective and must be replaced. If the resis-
tance of the power supply is correct, proceed to the
next test.
NOTE: Be sure the seal (27d) is in place on the end of
the power supply before installing the power supply
back into the gun.
Fig. 25
Fig. 26
L
15a
27d 27
29
03624
R
0441
308937 29