12
308-799
Troubleshooting
MOTOR WON’T OPERATE (Continued)
TYPE
OF PROBLEM
WHAT
T
O CHECK
If check is OK, go to next check
WHA
T T
O DO
When check is not OK refer to this column
Basic Electrical Problems
(continued)
Follow
Pressure Relief Pro
-
cedure on
page 7. Remove
gun from hose. Remove pres
-
sure control cover.
1
.
Check leads from motor to be sure they are
securely
fastened and properly mated.
1. Replace
loose terminals; crimp
to leads. Be
sure
terminals are firmly connected.
Clean
circuit board terminals. Securely re
-
connect
leads.
2. Check
for loose motor brush lead connections
and
terminals. See page 18.
2. Tighten
terminal screws. Replace
brushes
if
leads are damaged. See page 18.
3.
Check brush length
which must be 1/2” mini
-
mum. See page 18.
NOTE:
The brushes do not wear at the same
rate on both sides of the motor . Check both
brushes.
3. Replace
brushes. See page 18.
4. Check for broken or misaligned motor brush
springs. Rolled portion of spring must rest
squarely
on top of brush. See page 18.
4. Replace spring if broken. Realign spring
with
brush. See page 18.
5. Check motor brushes for binding in brush
holders.
See page 18.
5. Clean
brush holders. Remove carbon with
small cleaning brush. Align brush leads
with
slot in brush holder to assure free
verti
-
cal
brush movement.
6. Check motor armature commutator for burn
spots,
gouges and extreme roughness.
See page 18.
6. Remove
motor
and have motor shop resur
-
face
commutator
if possible. See page 27.
7. Check
motor
armature for shorts using arma
-
ture
tester (growler)
or perform spin test. See
page
17.
7.
Replace motor
. See page 27.
8. Check
motor control board (104) by perform
-
ing motor control board diagnostics on page
21. If diagnostics indicate, substitute with a
good
board.
CAUTION: Do not perform this check until
motor armature is determined to be good. A
bad motor armature can burn out a good
board.
8. Replace with new pressure control board
(104).
See page 21.
Refer to wiring diagram on
page 35 to identify test points
(TP).
1. Check power supply cord (79). Connect volt
meter
between TP1 (neutral) and TP2. Plug
in
sprayer
. Meter
must read 105 to 125 V
AC. Un
-
plug sprayer.
1. Replace
power supply cord. See page 19.
2. Check
ON/OFF
switch (80). Connect volt me
-
ter between TP1 and TP3 terminal on ON/
OFF
switch. Plug in sprayer and turn ON. Me
-
ter
must
read 105 to 125 V
AC. T
urn of
f and un
-
plug sprayer
. Reconnect TP3.
2.
Replace ON/OFF switch. See page 19.
3. Check motor thermal cutof f switch. Turn
sprayer OFF. Check for continuity between
TP4
and TP5 with ohmmeter
.
3. If
thermal switch
is open (no continuity), al
-
low
motor to cool. If switch
remains open af
-
ter motor cools, replace motor. If thermal
switch closes after motor cools, correct
cause
of overheating.
4.
Check all terminals for damage or loose fit.
4. Replace damaged terminals and recon-
nect securely.
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