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MOTOR WON'T OPERATE (Continued)
TYPE OF PROBLEM
Basic Electrical Problems
(continued)
Follow Pressure Relief Pro-
cedure on page 7. Remove
gun from hose. Remove pres-
sure control cover.
Refer to wiring diagram on
page 35 to identify test points
(TP).
12
308800
Troubleshooting
WHAT TO CHECK
If check is OK, go to next check
1. Check leads from motor to be sure they are
securely fastened and properly mated.
2. Check for loose motor brush lead connections
and terminals. See page 18.
3. Check brush length which must be 1/2 in. mini-
mum. See page 18.
NOTE: The brushes do not wear at the same
rate on both sides of the motor. Check both
brushes.
4. Check for broken or misaligned motor brush
springs. Rolled portion of spring must rest
squarely on top of brush. See page 18.
5. Check motor brushes for binding in brush
holders. See page 18.
6. Check motor armature commutator for burn
spots, gouges and extreme roughness.
See page 18.
7. Check motor armature for shorts using arma-
ture tester (growler) or perform spin test. See
page 17.
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.
1. Check power supply cord (79). Connect volt
meter between TP1 (neutral) and TP2. Plug in
sprayer. Meter must read 105 to 125 VAC. Un-
plug sprayer.
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 VAC. Turn off and un-
plug sprayer. Reconnect TP3.
3. Check motor thermal cutoff switch. Turn
sprayer OFF. Check for continuity between
TP4 and TP5 with ohmmeter.
4. Check all terminals for damage or loose fit.
WHAT TO DO
When check is not OK refer to this column
1. Replace loose terminals; crimp to leads. Be
sure terminals are firmly connected.
Clean circuit board terminals. Securely re-
connect leads.
2. Tighten terminal screws. Replace brushes
if leads are damaged. See page 18.
3. Replace brushes. See page 18.
4. Replace spring if broken. Realign spring
with brush. 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. Remove motor and have motor shop resur-
face commutator if possible. See page 27.
7. Replace motor. See page 27.
8. Replace with new pressure control board
(104). See page 21.
1. Replace power supply cord. See page 19.
2. Replace ON/OFF switch. See page 19.
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. Replace damaged terminals and recon-
nect securely.
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