Graco 390 Repair Manual page 10

Problem
Basic Electrical
See wiring diagram, page
27
10
What To Check
(If check is OK, go to next check)
1. Electric supply. Meter must read
100-130 VAC for 110-120 VAC
models and 210-255 VAC for 240
VAC models.
2. Extension cord. Check extension
cord continuity with volt meter.
3. Sprayer power supply cord.
Inspect for damage such as bro-
ken insulation or wires.
4. Fuse. Check replaceable fuse on
control board (next to ON/OFF
switch).
5. Motor leads are securely fas-
tened and properly connected to
control board.
6. Motor thermal switch. Yellow
motor leads must have continuity
through thermal switch.
7. Brush cap missing or loose brush
lead connections.
8. Brush length which must be 1/4
in. (6mm) minimum.
NOTE: Brushes do not wear at
the same rate on both sides of
motor. Check both brushes.
9. Motor armature commutator for
burn spots, gouges and extreme
roughness.
10. Motor armature for shorts using
armature tester (growler) or per-
form spin test, page 16.
11. Pressure control not plugged in
to control board.
What To Do
(When check is not OK, refer to this column)
Reset building circuit breaker, replace building
fuses. Try another outlet.
Replace extension cord.
Replace power supply cord. See page 25,
Power Cord Replacement.
Replace fuse after completing motor inspection.
See page 21, Fuse Replacement.
Replace loose terminals; crimp to leads. Be
sure terminals are firmly connected.
Clean circuit board terminals. Securely recon-
nect leads.
Replace motor. See page 26, Motor Replace-
ment.
Install brush cap or replace brushes if leads are
damaged. See page 18, Motor Brush
Replacement.
Replace brushes. See page 18, Motor Brush
Replacement.
Remove motor and have motor shop resurface
commutator if possible. See page 26, Motor
Replacement.
Replace motor. See page 26, Motor Replace-
ment.
Insert pressure control connector into control
board.
Troubleshooting
310824C