Electrical Tests; Test Gun Resistance; Test Power Supply Resistance - Graco PRO AA4500 Instructions Manual

The performance of the spray gun is 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 (18)
and the barrel resistor cartridge as well as the continu-
ity of the electrical path between the components.
CAUTION
The barrel resistor cartridge is part of the barrel
and is not replaceable. To avoid destroying the gun
barrel, do not attempt to remove the barrel resistor
cartridge.
Use megohmmeter 218–979 (A) and an applied volt-
age of 500 volts to complete these electrical tests.
Connect the leads as shown. See Accessories to or-
der the megohmmeter.
WARNING
To reduce the risk of sparking, which could cause
fire, explosion, or electrostatic shock and result in
serious injury, do not use the megohmmeter in the
hazardous area. Remove the gun from the hazard-
ous area before testing it.

Test Gun Resistance

Measure the resistance between the end of the elec-
trode (1a) and the air fitting (17). The resistance
should be between 329 to 401 megohms. If the resis-
tance is outside the specified range, go to the next
test. If the resistance is correct, refer to Electrical
Troubleshooting on page 23 for other possible
causes of poor performance.

Test Power Supply Resistance

Remove the power supply (18) from the gun. See page
34.
Measure the resistance from the power supply's
ground contact point (EE) to the contact inside of the
power supply seal (18e) [the conductive rubber contact
may be slightly recessed into the seal] . See Fig. 5.
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.
If you still have problems, refer to Electrical
Troubleshooting for other possible causes of poor
performance, or contact the nearest authorized service
agency.
NOTE: Be sure the seal (18e) is in place on the end of
the power supply before installing the power supply
back into the gun.

Electrical Tests

(See Fig. 4)
(See Fig. 5)
1a
Fig. 4
18e
18
Fig. 5
A
17
01949
A
EE
0441