Piper PA-24 Comanche Service Manual page 556

PIPER COMANCHE SERVICE MANUAL
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ACJfOR
MOUNTING
LUG
IIUSH
AND
TlIMINA..
ASIIM...Y
--'"~=::;..;;:
STATOR
ASSIMII,Y
'IGURE '.16. CROSS SECTIONAL VIEW Of ALTERMATOR
To remove the drive end frame from the totor, place the rotor in a vise and tighten only
enoueh to permit removal of the shaft nut.
CAUTION
Avoid excessive tiahtening as this may cauae distortion of the
rotor. Remove the shaft nut, ..alher, puUey, fan, and the collar,
and then separate the drive end frame from the rotor shaft.
9-49. Checks.
a. Rotor Checks - The rotor may be checked electrically for arounded, open, or short circuited
field coils. To check for grounds, COMect a
ll~volt
test lamp or an ohmmeterfrom either slip
ring to the rotor shaft or to the rotor poles. If the lamp lichts. or if the ohmmeter reading is low,
the field winding is Founded (FilUre 9-1i).
To check for opens, connect the test lamp or ohmmeter to e.ch slip ring. If the lamp fails
to light. or if the ohmmeter reading is
hip
(infinite), the windine is open (Fieure 9--1i).
The winding is ehecked for short·eircuits by connecdne a battery and ammeter in series
with the edees of the two slip rines. Note the ammeter reading and refer to Delco-Remy Service
paralf' ph 9-57 for specifications. An ammeter readine above the specified value indicates
short~
windincs. An altemate lIlethod is to check the resistance of the field by connecting an
ohmmeter to the two slip rinp (Fieure 9-17). If the resistance reading is below the specified
value. the winding is shorted. The specified resistance value can
be
determined
by
dividina the
voltage by the current liven in paraeraph 9-5;.
1£
the rotor is not defective. and the altemator fails to supply rated output when checked
as covered in the section entitled Checkinl Altemator Output, the trouble is in the stator or
ELECTRICAL SYSTEM
ISSUED: 8/18/72
3
810
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