Repair - Graco ULTRA 500 231-032 Instructions-Parts List Manual

MOTOR WON'T OPERATE
TYPE OF PROBLEM
Condition B (continued)
Both lamps off
REFER TO THE WIRING
DIAGRAM BELOW TO
IDENTIFY TP POINTS.
Condition C
Red lamps on,
Clear lamp off
Unplug sprayer!
.
307–758
18
WHAT TO CHECK
If check is OK, go to next check
6. Check motor thermal cutout switch. Connect
volt meter to TP6 female and TP9 female.
Plug in sprayer and turn on. Meter should read
105 to 125 VAC. Turn off and unplug sprayer.
7. Check microswitch (302). Reconnect TP6
connectors.Connect volt meter to TP15 male
and TP4. Meter should read 50–125 VAC.
8. Visually inspect microswitch (302) button. Ad-
justment stud should not depress button
when fluid pressure is zero. Depress button
with small screwdriver; audible click indicates
microswitch is in normal position.
9. Check microswitch (302) continuity with ohm
meter. Be sure sprayer is unplugged! Meter
should read zero ohms with no fluid pressure
in the sprayer.
10.Check all terminals for damage or loose fit.
Reconnect TP6 connectors.
11. Check circuit board (72) by substituting with a
good board. See page 28.
BLUE
WHITE
BLACK
YELLOW
RED
BLACK
GREEN
1. Check circuit board (72) by removing from
box without disconnecting wires; see page 28
for removal procedure.
WARNING: Removing circuit board while still
wired over–rides optical detector which may
cause sprayer to over–pressurize, if microswitch
does not function properly. Turn sprayer on
ONLY long enough to check lamp condition, then
shut off immediately.
WARNING: To reduce risk of electric shock,
handle board by edges only! Do not allow any
metal objects to come in contact with board!
Plug in and turn on sprayer. Clear lamp should
be on now. Turn off and unplug sprayer.
2. Check bourdon tube flag and detector posi-
tion. Reinstall circuit board (see page 28).
Turn pressure setting to maximum; flag
should extend less than half way into optical
detector slot from the bottom.
WHAT TO DO
When check is not OK refer to this column
6. Allow motor to cool. Correct cause of over-
heating. If switch remains open after motor
cools, check continuity between TP9 fe-
male and TP10 with ohmmeter. If open, re-
place motor.
7. Clean microswitch male terminals. Re-
place loose or damaged terminals. Se-
curely reconnect leads.
8. Microswitch is faulty. Return sprayer for

repair.

9. Microswitch is faulty. Return sprayer for
repair.
10.Replace damaged terminals and recon-
nect securely.
11. Replace circuit board. See page 28.
WHITE
MOTOR
THERMAL SWITCH
1. Replace circuit board. See page 28.
FLAG
OPTICAL
DETECTOR
CIRCUIT
BOARD
2. Perform pressure control adjustment to
see if that corrects problem. See page 30.
If not, replace bare pressure control. See
page 29.