Westerbeke W-46 - Alternator Inspection

ALTERNATOR/REGULATOR SERVICE
An alternate method for removing the Sllllor winding, brush
holder regullltor unit and the I.C. diode rectifier IUS(!mbly
from the rear bnu:ket. With the front bracket and rotor
assembly separated from the rear half of the alternator:
. 1. Insert a flat-bladed screwdriver between the stator core
and the edge of the rear bracket on the same side as the
brush-holder. Raise this side of the stator core away from
the bracket so as to open a gap of about 1/2 inch.
NOTE: Be careful not to allOw the screwdriver blade to
enter
for enough to touch the stator winding. ·
2. Maintaining the 1/2 inch gap, insert the screwdriver
between the stator core and the bracket on the rectifier
side and
move ·the stator laterally toward the brush-holder
for a distance of 1/2 to 3/4 of an inch without lifting it
from the bracket.
3.
Insert a #2 Phillips screwdriver through this opening and
remove the two screws holding the rectifier.
4. Remove the nut anchoring the B terminal bolt and the
capacitor mounted thereto on the outside rear of the
bracket. Then ren:~ove the third Phillips screw holding the
brush holder to the bracket.
S. Carefully withdraw stator, brush holder and rectifier from
the rear bracket as one loosely connected uniL
With the bracket out of the way, it is easy to unsolder the
stator winding leads from the rectifier quickly to avoid
heat damage to the diodes and I.C. chips. It is also easier
to renew the brushes because there is no need to bend the
connecting plates between the brush holder and the
rectifier and possibly damage the rectifier:
When reversing this procedure, make sure that the stator
· winding leads are gently pushed back (from possible contact
with the rotor body) after seating the stator into the rear
bracket.
INSPECTION
Diode
Diode troubles are classified as open-circuit and short-c.ircuit •
When the diode is open-circuited, oo current flows. In the
short-circuited diode, cu~nt flows in both directions.
Checking far Stunt Circuit
Check for continuity between the ( +) heat sink and the stator
coil lead joint terminal and between the (-) heat sink and the
said terminal. If each test shows current flow in both direc-
tions, the diodes are short-circuited. Replace the rectifier
assembly.
Checking fir Open Circuit
To check for an open circuit in the diodes which have passed
the short-circuit test, disconnect the diode leads and check
with your ohmmeter between the diode lead and the body,
reversing the leads. If no continuity is found, the diode is
open.
Checking Diode Trio
Check each of the three diodes for continuity. If any diode
allows current flow in both directions or does not allow
current to flow in one direction, replace the rectifier assembly.
Engines & Generators
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