Page 241
<4
~ 7
Changing brushes
Min. length of the brushes is 0.354 in. (9 mm). If the al-
ternator is renovated the brushes shall be replaced if they
are under 0.551 in. (14 mm).
1. Mark the position of the tension lug on the drive
bearing housing. Undo the bearing housing retaining
screws and remove the rotor with the bearing hous-
ing from the stator.
Undo both nuts holding the rectifier bridge in place.
N
3. Undo the terminal screw of the connecting wire to
the brush unit assembly (see illustration).
(Later alternator models are fitted with AMP-connec-
tions.)
ae S 1862
UNSCREWING THE BRUSH UNIT ASSEMBLY
DISCONNECTING THE BRUSH UNIT ASSEMBLY WIRE
4. Undo the brush unit assembly retaining screws and
remove the assembly (see illustration).
REMOVING THE BRUSH UNIT ASSEMBLY
Sept. 1973 SAAB 321-8
Page 242
5. Disconnect the wires with the help of a soldering iron; 6. Push up the brushes and secure them with the brush
the brushes can then be removed. When resoldering the springs. Fit the brush unit assembly and make sure
wire connections, make sure that no solder flows into that the spring washer is in its correct place in the
the wires. bearing seat.
7. Insert the rotor and screw the assembly together. Make
sure that the drive bearing housing is correctly posi-
tioned relative to the slip ring bearing housing. Press
the brushes down from the outside with a screwdriver
or similar.
a S186
UNSOLDERING THE BRUSH UNIT TERMINALS
Alternator, 2.0 | carburetor engine
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innit
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ALTERNATOR, 2.0 L CARBURETOR ENGINE
1. Drive bearing assembly
2. Stator
3. Slip ring end bracket
4. Rotor
5. Rectifier unit
321-9 SAAB Sept. 1973
Page 243
Disassembling
1. Hold the belt pulley with a suitable tool and unscrew
the nut with a 7/8” (22 mm) wrench. Remove the
pulley and fan.
2. Remove the brush unit assembly from the alternator,
$4015
BRUSH UNIT ASSEMBLY REMOVED FROM ALTERNATOR
3. Separate the stator and slip ring end bracket from the
drive bearing housing and rotor. Mark the position of
the drive bearing housing relative to the stator and
slip ring end bracket.
STATOR AND SLIP RING END BRACKET SEPARATED FROM
ROTOR AND DRIVE BEARING HOUSING
Sept. 1973 SARE
4. Unscrew the retaining screws and nut for the rectifier
unit and separate the stator and the rectifier unit from
the slip ring end bracket.
STATOR AND RECTIFIER UNIT SEPARATED FROM SLIP
RING END BRACKET
5. Unsolder the stator cables from the rectifier unit. Con-
cerning disassembly of bearing, see the section on dis-
assembly of the alternator for 1.7 and 1.85 | engines.
321-10
Page 244
Assembling
Concerning assembly of bearing, see the section on as-
sembly of the alternator for 1.7 and 1.85 | engines.
1. Solder the stator cables to the rectifier unit.
2. Assemble the rectifier unit and the slip ring end
bracket.
3. Place the snap ring for the bearing in the slip ring end
bracket and assemble the drive bearing housing and
rotor units together with slip ring end bracket and
stator in line with the markings made previously.
FITTING THE SNAP RING IN THE SLIP RING END BRACKET
321-11
4. Check the length of the brushes (see page 321—18)
and fit the brush unit assembly.
5. Fit the fan and belt pulley. Make sure the washers
are in the right order (see the picture). Tighten the
nut with a torque of 23—29 ft.lb. (34—39 Nm, 3.5—
4 kpm).
240 & 006 3
S019 »)
FAN AND BELT PULLEY WITH SPACERS AND BELT
Dec. 1975
Page 245
Make SEV
Alternator, 2.0 | injection engine
Disassembly
ay
. Remove the contact point and brush holder.
2. Remove the four socket head screws with square nuts
which hold the alternator together. Mark the position
of the drive bearing housing in relation to the stator
and slip ring cap.
3. Separate the slip'ring cap and stator assembly from
the drive bearing cap, rotor, fam and pulley assembly,
using two screwdrivers inserted in the slots on both
sides of the alternator between the stator and the
drive bearing cap. Never insert the screwdrivers deeper
than 0.08” (2 mm) as this may damage the stator
windings.
ALTERNATOR, 2.0 L INJECTION ENGINE
1. Drive bearing cap
2. Rotor
3. Stator
4. Slip ring cap
5. Exciter diodes (as from model 1973)
6. Protective diodes (model 1972)
SEPARATING THE STATOR AND SLIP RING CAP FROM
THE DRIVE BEARING CAP AND ROTOR
Sept. 1973 SAAB 321-12
Page 246
. Unscrew the nuts and remove the washers from the
positive and negative diode holders.
Separate the slip ring cap from the stator.
Clamp the rotor ina vise using the wooden blocks in-
tended for the purpose (tool 858002). Do not tighten
any harder than necessary to avoid deforming the ar-
mature cores.
UNSCREWING THE PULLEY NUT
Too! 858002
10.
ait
321-13
. Unscrew the nut and remove the washer, belt pulley,
fan, keypiece and spacer. Note which way the spacer
faces.
. Undo the three screws in the bearing cap.
. Push the rotor shaft out of the bearing cap with a
suitable puller, e.g. pinion bearing puller (tool
784115) from the Saab V4 repair kit.
Push the bearing out of the drive bearing cap.
Pull off the bearing at the slip ring end using the puller
mentioned above.
Reassembly
1. Press the bearing firmly on to the shaft at the slip
ring end and press on the inner ring.
2. Press the bearing into the drive bearing cap and press
on the outer ring.
3. Fit the plate in the bearing cap with the three slotted
screws.
4. Press the drive bearing cap complete with bearing
firmly on to the rotor shaft.
5. Fit the spacer, keypiece, fan, belt pulley, washer and
nut.
6. Tighten the nut to 29 ft.Ib. (40 Nm, 4 kpm).
7. Assemble the slip ring cap and the stator. Make sure
that the insulating washers and sleeves on the positive
diode unit are in place. Screw down the two diode
plates.
8. Check that the O-ring in the slip ring cap bearing seat
is fitted and that the vent hole is not blocked.
9. Assemble the drive bearing housing, rotor, fan belt
pulley with slip ring housing and stator. Tighten the
mounting screws with a torque of 2.2 ft.lb. (3 Nm,
0.3 kpm).
10. Fit the contact piece and the brush unit assembly.
SAAB Dec. 1975
Page 247
Testing — general comments
Note the following before testing the alternator or its
component parts:
Only direct current with a maximum voltage of 40 V
may be used to test the rectifiers.
A 40V/40W AC glow lamp should be used for insulation
and short circuit tests on stator windings and rotor wind-
ings. (Do not use a mains voltage of 110 or 220 V, since
this might damage the rectifiers.)
The battery cable must not be disconnected while the en-
gine is running for the purpose of measuring the charging
current.
If it is necessary to solder or unsolder diode connections,
the diode connecting wire must be held in a pair of flat
pliers to conduct away excess heat, on account of the
heat sensitivity of the semiconductors. (Solder and un-
solder the connections quickly with a hot soldering iron.)
Avoid mechanical strain at the point where the connect-
ing wires issue from the heat sink assembly; the wire must
not be bent or subjected to load at the point of attach-
ment.
During repairs to the alternator, whether in the car or on
a test bench, the battery must be disconnected.
Quick checking of alternator and charging regulator
If the charge indicator light does not go out, the first
thing to do is to check that the alternator belt is not slip-
ling and/or that the cable connections have not loosened.
If the lamp still glows after checking in this way, the
cause can be determined inthe following manner:
Remove the connector from the charging regulator.
Connect a cable between the red cable’s terminal D +
and the yellow cable’s terminal DF.
$2973
TERMINALS DF AND D+ CONNECTED
Sept. 1973
Start the engine and let it run at max. 2000 rev/min
while watching the charge indicator light.
WARNING
Do not run the engine at a higher speed than 2000
rev/min, as there is a risk of damage to the power
consumers being caused by overvoltage.
If the indicator light goes out immediately, the charging
regulator is defective and must be renewed.
If the indicator light flashes or lights continuously, the
alternator must be overhauled.
Measuring the charging capacity
The charging voltage and charging current can be mea-
sured in the car or on the test bench.
Measure the voltage using a voltmeter connected be-
tween terminal B+ and the alternator ground.
Measure the current using an ammeter connected in
series with the wire from terminal B+ on the alternator.
See the test values on page 321—18.
Page 248
Testing the alternator on a test bench
When on the test bench, the alternator must be driven by
its belt pulley only.
Connecting wires must be fitted with cable shoes or pin
connectors. Improvised connectors must not be used on
the battery either.
During testing a 12 volt battery must be coupled in paral-
lel with the alternator. The battery serves as a buffer to
damp out the peak voltages that occur when the load is
switched on and off. If these peaks exceed the permitted
maximum voltage, the rectifier effect of the diodes will
be lost. The voltage limit for silicon diodes is about 100 V.
Mounting the alternator
The alternator can be tested in most types of generator
test bench. In some cases it may be necessary to provide
suitable extra mounting and drive arrangements.
CAUTION
When mounted for testing the alternator must be
secured by screws in the normal manner and not
clamped in place or secured by other means.
Testing with the voltage regulator
Mount the alternator in the test bench and connect it to
the voltage regulator. Do not misconnect the terminals!
Connect the excitation ammeter to terminal DF on the
alternator. Connect the battery and indicator lamp. Con-
nect the voltmeter to terminal B+. For bias, increase the
speed from zero until an alternator voltage of about 14 V
is obtained, then reduce speed again.
Magnetization
Unlike a DC generator, the alternator does not demagne-
tize spontaneously after a long period of disuse. A 12 V
indicator lamp with a power of at least 1.2—2 W must
therefore be connected between terminals D+ and B+
(see wiring diagram). Bias current is then supplied to the
exciter winding through the indicator light, alternator
terminal D+, regulator terminal D+, the closed regulator
contacts and terminal DF. It is important in this con-
nection that the lamp wattage is at least as high as that
stated above. Self-excitation begins as soon as the alter-
nator voltage opens the exciter diodes, which occurs at
1-2 V. The voltage then rises rapidly and the potential
difference across the indicator lamp gradually diminishes.
The lamp remains lit until battery voltage has been at-
tained.
321-15
Testing the components
A. Rotor
Short circuit in the winding
Measure the resistance in the winding from slip ring to
slip ring using an ohmmeter.
The resistance should be:
4.0—4.4 ohm
3.8—4.2 ohm
Bosch alternator
SEV alternator
$4021
MEASURING THE RESISTANCE OF THE ROTOR WINDING
Short circuit to ground
Test the insulation of the exciter winding and the slip
rings for a short circuit to ground. )
Test equipment: 40V/40W AC glow lamp.
ad
$4022
CHECKING THE INSULATION OF THE EXCITER WINDING
AND THE SLIP RINGS
Sept. 1973
Page 249
Slip rings
Check that the surface of the slip rings is not greasy,
dirty or scratched. Clean using trichloroethylene. Avoid
polishing the surface of the slip rings. A ring which is
too highly polished may impair the electrical contact of
the brushes.
B. Stator
Short circuit in the windings (rectifiers unsoldered)
The test for a short circuit in the stator windings can be
made by probing with a winding tester. This test can only
be made when the alternator is disassembled. A further
possibility is to measure the joint resistance in two phases.
Three measurements will reveal any deviation in the re-
sistance of the stator winding. If the phases are marked
U, V and W, measure U—V, U—W and V—W. In each case
the reading should be (at 68°F /20°C):
Bosch 35 A alternator: 0.26 ohm + 10 %
Bosch 55 A alternator: 0.14 ohm + 10 %
SEV 55 A alternator: 0.15 ohm + 10 %
$4023
MEASUREMENT OF RESISTANCE ACROSS TWO PHASES
(v—w)
Dec. 1975
Short circuit to ground (rectifiers unsoldered)
The test should be made with a 40V/40W AC glow lamp.
Connect the glow lamp between the iron core of the
stator and each of the disconnected stator cables.
TEST OF STATOR WINDING
C. Rectifiers
Testing the rectifiers
Use only a testing lamp of not more than 40 V di-
rect current or an ohmmeter. To test the conduct-
ing and non-conducting directions of the silicon rec-
tifiers, the phase terminals must first be disconnect-
ed, as it is otherwise impossible to tell which diode
is faulty. The positive diodes between terminal B+
and phase conduct from the terminal to the casing
but not from the casing to the terminal. The nega-
tive diodes connected between phase and B— (inverse
polarity) conduct from the casing to the terminal but
not from the terminal to the casing (see illustration).
To test this, connect the testing lamp in series with the
diode under test. The lamp should light up when B+ is
connected to the anode of a diode with normal polarity.
The lamp should not light up when B+ is applied to the
casing. If the diode has inverse polarity, the lamp will
light up when B+ is connected to the terminal (cathode)
but not when the direction of current flow is reversed.
A faulty diode that fails to pass current in the conduct-
ing direction has been overheated by excessive current
intensity. A diode that passes current in both directions
has probably been subjected to excessive voltage.
321-16
Page 250
Terminal
Terminal
(anode) (cathode)
g Conducting
Cocdurting Mon-conducting direction
direction direction
Casing Casing
+ Diod = Dios
S$ 2227
Testing rectifiers with an ohmmeter D. Checking the brush unit assembly and connections
(brush unit assembly detached or rotor removed)
The rectifiers can also be tested with an ohmmeter. In a
properly working diode, resistance is low in the conduct- . Check the movement of the brushes in the assembly.
ing direction (e.g. a few ohms) but much greater in the 2. Check the wear of the brushes. Compare with wear
non-conducting direction (e.g. several kiloohms). limits on page 321—18.
3. Check that the brushes are completely insulated from
each other. Connect the testing instrument between
two brushes.
4. Check that the contact between each of the brushes
and the ’—" and DF” terminals is good.
E. Insulation test on assembled alternator
After disassembling and assembling the alternator, check
the insulation between the B+ terminal and ground with
an insulation tester.
$3878
CHECKING THE DIODES
321-17 SAAB Dec. 1975