Yanmar 4LHA-HTP Operation Manual page 647

Chapter 9 Electrical System
4. Alternator
2) To replace the IC regulator, disconnect the soldered
joint of the IC regulator and pull out the two bolts. Do
not remove these two bolts except when replacing the
IC regulator.
4-8 Inspection and adjustment
(1) Diode
Between terminals
Tester wire
+ side
u.v.w. u.v.w.
- side
Between terminals
Tester wire
+ side
u.v.w. u.v.w.
- side
+ side diode-i
- side diode
/
Current direction
Current flows only in one direction in the diode as
shown in Fig. 181. Accordingly, when there is continui-
ty between each terminal (e.g. BAT and U), the diode is
in normal condition (photo). When there is no continui-
ty, the diode is defective.
When the tester is connected in the reverse of above,
there should be no continuity. If there is, the diode is
defective.
BAT ( + side diode)
+ side - side
—~~~ No continuity
Continuity
E ( - side diode)
- side
+ side
Continuity
No continuity
W
- o L
j — j - Auxiliary diode
-o BAT
- - E
U.V.W.: terminal from the stator coil
After repeating the above test, if any diode is found to
be defective, replace the diode assembly. Since there is
no terminal on the auxiliary diode, check the continuity
between both ends of the diode.
CAUTION: Do not use high tensile insulation resistance
such as meggers, etc. for testing. The diode
may burn out.
(2) Rotor
Inspect the slip ring surface, rotor coil continuity and
insulation.
1) Inspecting the slip ring surface
Check if the surface of the slip ring is sufficiently
smooth. If the surface is rough, grind the surface with
No. 500—600 sand paper. If it is contaminated with
oil, etc., wipe the surface clean with alcohol.
Slip ring outer dia.
1
2) Rotor coil continuity test
Check the continuity in the slip ring with the tester. If
there is no continuity, there is a wire break. Replace
the rotor coil.
Resistance value
9-21
, 4LHA Serie
Wear limit
Standard
030.6mm
0 3 1 . 6 m m
(12049in.)
(1.2441 in.)
Approx. 3.34Q at 20 C
o