Piper PA-24 Comanche Service Manual page 564

currPnt ratin,. The specified volta,e aad the
current ratinc v.lues are found in paraaraph
9·Si.
1.
If the ntaclinc is the .am. u the cal-
ciliated value. proceed
to
part b.
2. If :eadinC is lIlueh hieber (hlfinite)
than the c.lculated. value. proceed to pan b.
3. If Nadine is zero. cheek for a .bort
between "NEG" aad "FLO" Ie", or for
a
crounded "FLO" 1 .... Circuit trac. _ill be
burned open
between
points A.A.
B.S. or C·C,
Fipre 9-26.
4.
If re.dinl i. low, altemator field
windinl is shorted. Circuit trace may be burned
between points A.A.
B.a. or C.C. Filunt
~26.
!
D
/Ii
C
D
PIPER COMANCHE SERVICE MANUAL
lllGUIE '.26. IEGUL.4TOR
CHECKS
•
MOTE
To expo.e the printed circuit for riewinl,
NIlOYe
the bottom plate
from the replator. the three p.... l
board .ttacbinc scre.... the
traa.istor attacbinc screw•• and then seperate th. heat sink from
the puel board.
b. With switcb turned ON. COMect voltmeter u .bown in Step.2, FilUre 9-24. Make
Sute
posi-
tive
(+)
and necative (.) voltmeter lead. are connected .. shown.
c. If meter reads battery volt••• cliscOMect Ie.:! at altemator "Fl" (field) terminal.
1. If readinl is still battery volt'Ce. -iriac is not defective. and no lIlore wirinl tests need
be
made.
2. If volt'Ce readinl is
,ero.
the "NEG" and "FLO" leads are reversed. Circllit trace
will be burned open between points A.A.
B.a. or C-C, Filure 9-26.
d. If meter ntads :rero volt..... discoanect lead at altemator "Fl" (field) terminal. and connect
a jumper lead from this lead to the battery po.itive
(+)
pa.t. See FiCUfe
~2S.
1. If meter now read. battery votta•• the "POS" ad "FLO" leads are reversed. This
lUisconnection alone will not cause the cizeuit trace to be
burDed open.
2. If meter now reads backward•• altamator tield terminal i. connected to reculatornelatin
terminal. the positive line is connected to telUlator field terminal. aDd recu1ator positive terminal
is connected to nelative side of circuit. Eith.r the circuit trace will
be
bumed between points
C·C. 0-0, or E.E. Fipre
~26;
or the driver transistor .ill
be
open. In either ca.e. the driver
bias resistor will have been overbeated.
e. If voltmeter reads backwards. discOftnect lead at altemator "Fl" (tield) terminal.
1. If meter still reads backwards. the "POS" IU.ld "NEG" leads .re reversed. The circuit
trace may be bumed between points C.C. 0.0. E.E. or F.F. Fipre 9.26. The transient suppres-
sion diode always will be open or shorted.
2. If meter now reads zero, the pclsitive Une is connected to reculator
"~EG"
terminal. the
nelative line is cOMected to the reculator "FLO" terminal, and the alternator 'FI" (field)
ELECTRICAL SYSTEM
ISSUED: 8/18n2
3 818
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