TESTING
ALTERNATOR
For tesfing this system, use
a
voltmeter-ohmmeter
such
as
a
Simpson
270.
Listed below are various
alternator problems with individual test procedures
following.
No
Output
-
Stator Assembly
Examine 1ead.wires for loose or broken connections at
the regutator and rectifier. Use the
Rxl
scale on the
ohmmeter for detecting opens
in
the stator. Dis-
connect the three wires that come from alternator
stator (two black, one red). Connect ohmmeter test
leads
to
red leadwire and ground to check continuity.
The ohmmeter reading should be about 2.0-ohms.
See Figure 18.
Next connect meter
to
black leadwires and ground.
Approximately 0.1-ohm should be read from either
black lead
to
ground. If noconnection existsbetween'
ground and black leads, stator assembly should be
replaced.
TEST
Battery voltaye
-
unit
not
running.
Checking Rectifier Assembly
Examine each of the two diodes for breakdown by
connecting. ohmmeter (Rxl scale) to one black lead
and to the white lead. Meter should read 10-ohms
in
proper polarity.
A
shorted diode would readzero res-
istance and would cause a short circuit through the
lead winding when in operation. An open diode
would read infinite in both directions, indicating that
replacement is necessary.
VALUE
12 Volts
DC
TESTING
REGULATOR
ASSEMBLY
To
check for proper voltage regulation, attach a
DC
voltmeter to battery and operate engine at ap-
proximately
I800
rpm. Battery voltage will climb to
the present factory setting (14.2 to
14.8
volts).
.
Some installations may vary due to voltage drop
in
the length
of
ammeter harnesses. Other variations may stem from a
loose
connector in the harness or loose or corroded battery
leads.
LOW
voltage readings at the battery mean poor battery connections.
To
test regulator, remove connector. Using the
Rx10,OOO scale of the ohmmeter, connect one meter
lead to red leadwire arid other meter lead to regulator
base. See Figure 18.
No
deflection should be noted
on the ohmmeter
in
either polarity. Next connect
meter
to
black leadwire and base of regulator. Meter
will
deflect fuily
in
one polarity, with no deflection in
the other.
AC
voltage from stator with plug disconnected and
unit running at approximately 1800
rpm.
Ohmmeter reading at plug when checking two AC
stator leads
-
unit not running.
Full
Charge
-
Will
Not Regulate
Check for broken leads at connection to regulator
plates.
To
be sure regulator winding operates proper-
ly,
connect red lead to ground and start engine.
A
maximum
of
4
amperes should be noted. This would
indicate stator winding is satisfactory.
If
so,
replace
regulator.
23
VAC
minimum'
.
Black to Black
0.5
to 0.7-Ohms"
Black to Black
No
Charge
If
alternator does not charge when load
is
applied to
battery, shut off engine and disconnect one red
leadwire from regulator terminal. Be sure lead is
taped or isolated from conducting engine
parts.
Once
again, start engine. Alternator should charge
to
full
output; if it doesn't, replace stator assembly.
TESTING
20
AMP
SYSTEM
I
Battery voltage with
unit
running at
1800
rpm
or
more.
1
14.2
-
14.8
Volts
DC
'
I
-
-
48
VAC
maximum at
3600
rpm, Red
to
Ground.
**
-
Resistance values (Ohms) are as follows between wire pairs.
32
Redistribution or publication of this document
by any means, is strictly prohibited.
Redistribution or publication of this document
by any means, is strictly prohibited.
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