Failure to remove the exciter field leads from the
automatic voltage regulator during flashing
procedures may destroy the regulator.
2. Connect the F+ and F- leads to the battery’s
corresponding positive and negative terminals. This
should be done using an appropriate length of lead wire
to separate the battery from the point of connection
(batteries may explode when exposed to an electric arc).
After 3 to 5 seconds, remove the F- lead. An inductive arc
should result. If no arc is drawn, repeat the procedure.
3. Reconnect the F+ and F- leads to the regulator. Restart
the generator and verify that terminal voltage is
developed. If terminal voltage does not develop, repeat
the field flashing procedure and / or consult the trouble
shooting section.
BEARING REMOVAL
Prior to performing this operation, it is suggested that the
alternator's shaft be rotated until two of the main rotor poles
are in a vertical position. Once the bearing bracket is backed
out, the rotor will drop on the main stator core. Having the
rotor in this position will limit the amount of rotor drop to that
of the air gap. Visually inspect the bearing bore for damage or
wear. If worn or damaged, replace prior to reassemble.
Opposite Drive End Bearing Bracket Removal.
Prior to proceeding with bracket removal, disconnect exciter
field leads F+ and F- from the automatic voltage regulator and
ensure that they are free to move when the bearing bracket is
removed. Remove the bearing bracket retaining bolts. Using a
pair of screw drivers, wedge the bracket off the frame. After
approximately 1/8 inch, the bracket will clear the locating
register on the frame and will drop until the rotor is resting on
the main stator core. Continue to pull the bracket free from the
bearing. Visually inspect the bearing bore and o-ring (if
equipped) for damage or wear. If worn or damaged, repair or
replace prior to reassembly.
Drive End Bearing Bracket Removal,
Two Bearing Units.
Remove any drive arrangement from the generator shaft
extension. Remove the bearing lock ring retaining screws.
There is no o-ring in the drive end bearing bracket. The shaft
extension must be supported before proceeding further. A
hoist and sling, jack, or some other means of support with a
capacity of 2 tons should be used.
Remove the bearing bracket retaining cap screws. Using a flat
bladed screw driver or chisel, pry the bracket back from the
frame. After approximately 1/8 inch, the bracket will clear the
locating register on the frame. Lower the shaft extension until
the rotor is resting on the main stator core. Continue to pull
the bracket free from the bearing. Visually inspect the
bearing bore for damage or wear. If worn or damaged, sleeve
or replace prior to reassembly.
Reassembly note: Before the bearing bracket is seated
against the frame, a threaded rod may be used to help align
the inner bearing cap with the bearing bracket.
BEARING REPLACEMENT
Using a bearing puller, remove the existing bearing. It is
strongly recommended that the bearing be replaced any time
the it is removed from the shaft. ALWAYS install the same
type and size bearing that was supplied as original
equipment. Order by part number from the parts list, and
include the unit serial number and part number when
ordering. Heat the bearing to a maximum of 100°C (212°F) in
an oven. Apply a thin coat of clean lubricating oil to the press
fit area of the rotor shaft. Using suitable heat resistant gloves,
install the bearing over the end of the shaft until it seats
against the shaft shoulder. The bearing should slide on the
shaft and be seated without excessive force. Should the
bearing bind on the shaft prior to being seated against the
shoulder, a piece of tubing slightly larger than the press fit
area can be used to drive the bearing to its final position.
Using light taps with a soft mallet, apply pressure to the inner
race only.
RECTIFIER ASSEMBLY REMOVAL
The rectifier assembly cannot be removed until the opposite
drive end bearing bracket and bearing have been removed
(see bearing removal procedure). Remove the three exciter
rotor leads from the heat sinks and the two main rotor leads
from the main rotor posts (see Figures 5). Remove the screws
securing the rectifier assembly and pull the assembly free
from the shaft.
DIODE REPLACEMENT
Prior to installing a replacement diode on the heat sink, apply
a thin film of conductive heat sink compound around the base
of the diode (do not coat the threads). When installing a diode
on the heat sink, care should be taken not to over torque the
retaining nut which could cause damage to the device. Torque
to 28 pound inches. If not damaged, the existing diode lead
wire may be unsoldered from the failed diode, and resoldered
on the replacement.
14
