Magnum XR Series Service Instructions Manual page 13

SPECIFIC PROBLEM
Pump cycles, but output is low
or surging.
Advanced Troubleshooting
General Problem: Output is Low or Fluctuating
CAUSE
See Basic Troubleshooting page 8.
Pump valves are worn.
Spray–Prime/Drain valve is leaking.
Voltage from electrical outlet is too low. Low
voltages reduce sprayer performance.
Extension cord is too long or not a heavy enough
gauge.
Leads from motor to control board are damaged,
loose, or overheated.
Motor brushes are worn.
NOTE: Brushes do not wear at the same rate on
both sides of motor. Check both brushes.
Motor brush springs are broken.
Motor brushes are binding in brush holders.
Motor stops before sprayer reaches correct
pressure (stall pressure is too low).
Motor armature is shorting.
Control board is damaged.
CAUTION: Do not perform control board
diagnostics until you have determined that the
armature is good. A bad motor armature can burn
out a good control board.
SOLUTION
Check for worn pump valves as follows:
Prime sprayer with paint. Trigger spray gun
momentarily. When spray gun trigger is
released, pump should cycle momentarily
and stop. If pump continues to cycle, pump
valves may be worn.
See Pump Service on page 23.
Check Spray–Prime/Drain valve for debris
trapped on seat and for worn parts. Torque to
185 in-lb (21 NSm). Replace if parts are worn.
See Spray–Prime/Drain Valve Kit on
page 28.
Check voltage of outlet. Meter must read
85 to 130V AC.
Reset building circuit breaker or replace
building fuse.
Repair electrical outlet or try another outlet.
Replace extension cord.
See Grounding and Electrical
Requirements on page 6.
Be sure terminals are centered and firmly
connected. Inspect wiring insulation and
terminals for signs of overheating, and
replace any loose terminals or damaged
wiring. Securely reconnect terminals.
Check length of brushes. Brush length must
be 0.25 in. (6.4 mm) minimum. Replace
motor if brushes are worn.
See Motor Kit on page 18.
Replace motor if springs are broken.
See Motor Kit on page 18.
Clean brush holders, remove carbon dust
with small cleaning brush.
Replace pressure control switch.
See Pressure Control Switch Kit on
page 22.
Check for shorts using armature tester
(growler), or perform spin test (see Motor
Diagnostics on page 16). Replace motor if
shorts are evident.
See Motor Kit on page 18.
See Control Board Diagnostics on page
16, and replace control board if damaged.
See Control Board Kit on page 17.
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