Saab 95 1967, Руководство по обслуживанию

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TESTING
Please note the followmg pomts before testing the alter-
nator or parts thereof.
aggzsciay only be tested With D.C. voltages not exceed-
Glim glowing lamps (110 V or 220 V) may not be used
for insulation or short CerUlt tests, as they may damage
the diodes.
The 80 V 40 W test voltage for the stator winding insula-
tion test may only be applied if the diodes are discon-
nected.
While the engine is running, battery terminals may not be
disconnected to check the charging current on the vehicle.
Semi-conductors are extremely sensitive to heat. To pre.
vent excessive heat when soldering, use a pair of flat pliers
to hold the supply wire near the diode. (Use a hot iron and
be as quick as possible.) Any mechanical damage to the
diode connecting wires must be avoided, e.g. do not bend
or load the wire directly on the diode.
The battery must be switched off or disconnected before
any repair work commences on the alternator, either while
in the vehicle or on the test bench.
Only instruments having not more than 8 V voltage may
be used for measuring resistances on the accembled alter-
nator.
Testing alternator on bench
On the test bench, the alternator must be driven with its
own pulley only. All connections must be made with cor—
rect size cable shoes, or with spade terminals. Do not im-
provise the battery connection.
A 12 V battery must be connected parallel to the alter-
nator when testing. The battery will act as a buffer and
smooth off any peak voltages arising from switching on
or off the load.
Peak voltages exceeding the maximum permissible value
will damage the rectification effect of diodes. The maXi-
mum permissible peak voltage on silicon diodes is approx.
50V.
Excitation
Contrary to D.C. generators, alter
citing properties after long storage-
nators lose their selfex-
Therefore a charge in-
dicator light of 12 V and minimum 1.2—2.0 W must be
COnnected between terminals D+ and 3+ according to
wiring diagram. The pre-exciting current will then flow
t"""NJ'SIh the charge indicator light, 0+ on the alternator,
BF to the exciter coil fitted to the rotor. It is most im-
portant that the charge indicator light bulb is minimum
1.2—2.0 W. Self-exciting commences as soon as the alter-
nator voltage opens the exciter diodes, which occurs at
about to 2 volts. From there on, the voltage increases
rapidly, the voltage difference on the charge indicator
light bulb decreases, and the bulb will go out as soon as
battery voltage is achieved.
Mounting of the alternator
The alternator can be tested in most types of alternator
test benches. In some cases it may be necessary to add
special mounting- and driving devices.
CAUTION
When testing the alternator, it must be mounted in
its normal attachment and not e.g. fastened by
damping.
Testing
with regulator
Mount the alternator to the test bench and connect it to
the voltage regulator.
00 not mix up connections!
Connect the exciter current ammeter to terminal BF on
alternator. Switch on battery; switch on charge indicator
light. Connect voltmeter to terminal B+. To pre-excite
the alternator, increase the speed from zero until the out-
put voltage is approx. 14 V, then decrease speed again.
Testing 2/3 of maximum output current
Switch on battery and load the alternator. Adjust the
speed to exactly 2 000 r/min. The alternator output must
now be 2/3 of maximum current = 23 A.
Testing the r/min at maximum output
Leave the battery switched on. Increase the load on al-
ternator and let it warm up. Increase speed. Max. output
(35 A at 14 V) must be achieved at 2 700—3 700 r/min.
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