Westerbeke BCGB Service Manual page 74

BATTERY CHARGING CIRCUIT
I
BRIDGE RECTIFIER
TESTING THE BATTERY CHARGING CIRCUIT
NOTE:
The battery charging circuit is totally separate from the
A C output of the generator: The generator output affects the
circuits output, but not the reverse.
Normal AC voltage running to the rectifier (while the
engine is operating at 1800 rpm) is measured across the
two AC connections on the bridge rectifier (shown below).
AC VOLTAGE TO THE BRIDGE RECTIFIER (APPROXIMATELY):
No-load off the generator
Full-load off the generator
MEASURING DC
; VOLTAGE BETWEEN .' •
. (+) AND (-) LEADS .,:.'
II
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,
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16.0 volts AC
17.5 volts AC
Normal DC voltage running out of the rectifier (in volts
DC) is measured across the two DC connections of the
bridge rectifier, that is + and - as illustrated.
DC VOLTAGE FROM THE BRIDGE RECTIFIER (APPROXIMATELY):
No-load off the generator
Full-load off the generator
17.0 volts DC
18.5 volts DC
Lift the two AC wire leads off the bridge rectifier and
measure the resistance between these two leads. It should
measure 0.14 ohm. No continuity should exist between
these two leads and the ground or the main stator windings.
RESISTANCE BETWEEN AC LEADS 0.14 OHMS
RESISTANCE BETWEEN DUAL EXCITERS 0.08 OHMS
ALSO TEST THESE TWO LEADS
TO THE AC TERMINAL BLOCK
STUDS TO VERIFY NO CONTINUllY
TESTING THE BRIDGE RECTIFIER
1. Set your multimeter's scale on RX1 (+DC) and set the
needle to zero.
2. Connect the (+) positive lead from the
mu~timeter
to point
#4. Taking the multimeter's negative (-) probe, momentarily
touch points #1, #2, #3, and #5. The multimeter should
register no deflection for any of the points touched.
3. Remove the positive (+) probe from point #4 and connect
the negative (-) probe, momentarily touch points #1, #2,
and #3. The multimeter's needle should deflect when each
point is touched.
4. Leaving the negative multimeter (-) probe on point #4,
touch point #5 with the positive probe. No deflection should
take place.
S. Place the positive (+) probe on point #1 and the negative
probe (-) on point #3. The multimeter again should not
register any deflection (no deflection indicates infinite
resistance). Reverse these connections and the multimeter
snould again register no deflection.
/
#5
MOUNTING HOLE'
#3
#2
BRIDGE
RECTIFIER
Engines & Generators
67