Removal And Installation - Cessna 1969-1976 172 Series Service Manual

16-39. TROUBLE SHOOTING THE ALTERNATOR SYSTEM (Cont).
I
TROUBLE
ALTERNATOR SYSTEM
TERY CHARGED (Cont).
WILL NOT KEEP BAT-
ALTERNATOROVERCHARGES
EXCESSIVE WATER.
BATTERY
-
BATTERY USES
PROBABLE CAUSE
Faulty wiring between alter-
nator and regulator, or
faulty alternator (Cont).
Regulator faulty
o r
improperly
adjusted.
Regulator faulty o r improperly
adjusted. Faulty sensor switch.
REMEDY
5. Check resistance from "F"
terminal of regulator to "F" ter-
minal of alternator. Normal
indication is a
very low resis-
tance. If reading indicates no,
or poor continuity, repair or
replace wiring from regulator
to alternator.
6. Check resistance from "F"
terminal of alternator to alter-
nator case. Normal indication
is 6-7 ohms. If resistance is
high o r low, repair or replace
alternator.
7 .
Check resistance from case
of alternator to airframe ground.
Normal indication is very low
resistance. If reading indicates
no, or poor continuity, repair o r
replace alternator ground wiring.
Check bus voltage with engine
running. Normal indication
agrees with voltage v s temper-
ature chart on page 16-13. Ob-
serve ship's ammeter, ammeter
should indicate near zero after
a
few minutes of engine operation.
Replace regulator.
1. With engine running turn off
and on battery portion of the
master switch. If the light stays
on shut down engine then turn on
the "BAT and "ALT" portions of
the master switch. Check for
voltage
at
the "S" terminal of the
voltage regulator. If voltage is
present adjust
or
replace
regula-
tor. If voltage is not present
check master switch and wiring
for short or open condition. If
wiring and switch a r e normal
replace sensor.
16-40. REMOVAL AND INSTALLATION. (GEAR
DRIVEN ALTERNATOR). (Refer to figure 16-3. )
a.
Ensure that the master switch
is
off and the
negative lead is disconnected from the battery.
b. Remove wiring from the alternator and label.
c. Remove screw and nut holding blast tube to
support s t r a p clamp, blast tube will then be f r e e for
removal.
d. Remove nuts and washers from alternator mount-
16-41. REMOVAL AND INSTALLATION. (BELT
DRIVEN ALTERNATOR). (Refer to figure 16-4. )
a.
Ensure that the master switch is off and the
b. Remove wiring f r o m the alternator and label.
c. Remove safety wire from the upper adjusting
d. Remove safety wire from lower adjusting bolt
negative lead
is
disconnected from the battery.
bolt and loosen bolt.
and remove bolt.
ing bolts. e. Remove the locknut from the alternator mount-
Remove the alternator drive belt and the alter-
e. Remove alternator. ing bolt.
f . To replace alternator, reverse this procedure.
f .
16-11