Troubleshooting & repair, Rotor resistance test (continued) – Lincoln Electric POWER-ARC 4000 SVM103-A User Manual
Page 54
POWER-ARC 4000
TROUBLESHOOTING & REPAIR
F-13
ROTOR RESISTANCE TEST (continued)
FIGURE F.2
LOCATION OF ROTOR SLIP RINGS - BRUSH HOLDER ASSEMBLY REMOVED
SLIP
RINGS
TEST PROCEDURE
1. Conduct the test with the gasoline engine
OFF.
2. Remove the spark plug wire to prevent
accidental engine kickback or starting.
3. Isolate the rotor electrically by removing
the generator brushes. Refer to Figure F.2
as you perform the remaining steps.
4. Open the brush holder assembly cover.
Squeeze the 2 tabs and depress the cover
at the top with a screw driver or your fin-
gernail. The cover will drop open on its
bottom hinge.
5. With the 1/4” nut driver, remove the 2
screws that hold the brush holder assem-
bly in place.
6. Slide the brush holder assembly out and
lay it aside, held by the 2 wires attached.
7. Measure the resistance across the rotor
slip rings.
A. Set the ohmmeter on the low scale
(X1).
B. Place one meter probe on one of the
rotor slip rings. Place the other
probe on the other slip ring.
C. Check the resistance across the slip
rings. It should read 7 - 8 ohms.
8. Measure the resistance to ground.
A.. Set the ohmmeter on the high scale
(X100,000).
B. Place one probe on either of the slip
rings. Place the other probe on any
good, unpainted ground. Use the
ground stud or the rotor thru-bolt.
C. Check the resistance. It should read
very high, at least .5 megohm
(500,000 ohms).
If the resistance checks meet the specifica-
tions, then the rotor is okay.