Yanmar 4LHA-HTP Operation Manual page 655

Chapter 9 Electrical System
4. Altemator
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.
4-11.8 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.
- side
M M
+ side diode-
- 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. When there is no continuity, the
diode is defective.
When the tester is connécted 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
t^oniinuiiy
No continuity
w
o
-o L
- j - Auxiliary diode
\ J _ P o BAT
Jr 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 bum 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.
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
4LHA Seri,
Wear limit
Standard
030.6mm
031.6mm
(15441 in.) (12049in.)
A p p r o x . 2.58 H a t 20° C