Piper Comanche PA-24 Service Manual page 687

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PIPER COMANCHE SERVICE "ANUAL
10IIa fIOI SIIOI" AND
""""I
FIGURE 9.17. CHECKING ROTOR
rectify in, diodes.
b. Stator Checks - To cbeck the stator
winmas, remove all three
Itator
lead attachiDI
nats (Fi ..... 9-(8). and th.a .. parat. the stator
assembly &om the .nd fr..... The fit between
Itator frame and end frame
is
not ticht, aDd the
two can be .. paratee! easily. -
Th. stator windin." .. ay be checked
",ith a liD-volt test lamp or an ah .... eter. If
the la .. p Ii.bts. or if the meter rudin,
is
low
.. ben caanectee! fro.. any stator lead to the
frame, the ",indin.s are
""""ciecI.
If the lamp
fails to licht, or if meter readiD,
is
bich when
successively
COM.ected
between each pair of
stator leads, the "'indinls
on
open (Figure
9-(9).
A short circuit in the stator windings is
difficult to locate without laboratory test equip-
ment due to the low resistance of the windials.
However, if aU other electrical checks are
normal and the generator fails to supply rated output. shaned stator windinp are indicated.
c. Diode Checks - Each diode may be checkee! electtically far a sbartee! or open condition.
Anyone of the .. ethods outlined below may be usee!.
Ohmmeter Method: One method of cbeckinl diodes is to use an ordinary ohmmeter commonly
found in service stations. The lowest
rance
scale on the obmmeter should be used. and the ohm-
meter should have a
l~
yolt cell. To determine the cell volta •. tum the selector to the lowest
scale, and then connect the ohmmeter leads to a voltmeter. The voltmeter will indicate the cell
voltage.
BlUSH HOLDIR
ASSIMILY
FIGURE 9.18. SLIP RING END FRAME
3811
FIGURE 9·19. CHECKING STATOR
ELECTRICAL SYSTEM
ISSUED:
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