Mooney M20K - Page 140

SERVICE
AND
MAINTENANCE
MANUAL
M20K
MOONEY
AIRCRATT
CORPORATION
TROUBLE
SHOOTING
CHART-PROPELLER
DE-ICE
(con’t~)
TROUBLE
PROBABLE
CAUSE
REMEDY
Ammeter
shows
excess
Power
lead
shorted
to
ground.
Teminal
C
(28V).
Disconnect
current over
entire
cycle.
harness
at
brush
assembly
and
repeat
check
for
applicable
brush
assembly
hamess
connections.
(See
Section
30-60-01).
If
ground
is
indicated,
locate
and
correct.
Ammeter
faulty.
Test
ammeter
per
Section
30-62-00.
Ammeter
indicates
normal
Short
to
ground
or
short
Disconnect
leads
at
brush
block
current
part
of
cycle,
excess
between
adjacent
circuits,
timer
assembly
timer.
With
"Megger",
current
remainder
of
cycle.
to
brush
block
check
insulation
resistance
from
(12V
aircraff
only)
power
leads
to
groung
and
between
adjacent
circuits.
If
shorted
or
grounded,
locate
8
repair.
Short
between
slip
rings.
Clean
slip
ring
assembly
with
MEK.
Short
to
ground
or
between Eledn’cally
isolate
brush
assembly
adjacent
circuits
in
brush
block.
and
test
per
Section
4-6,
B.F.
Goodrich
Report
68-04-7128.
Short
to
propeller
or
short
Isolate
brush
assembly.
WRh
between
two
adjacent
"Megger",
check
insulation
circuits-slip
n’ngs
to
De-leers.
resistance
from
one
rign
of
slip
n’ng
assembly
to
bare
prop.
Reading
should
be
as
least
.5
Megohoms
after
one
minute.
If
not
OK,
disconnect
the
slip
ring
leads one
set
at
a
time
to
trace
short.
If
OK,
disconnect
slip
n’ng
leads
and
check
insulation
resistance
between
slip
rings;
reading
should
be
at
least
.5
megohms
after
one
minute.
If not
OK,
clean
assembly
thoroughly
with
standard
solvent
and
wipe
clean
with
MEK
and
retest.
Replace
as
required.
Timer
faulty.
Test
timer
per
Section
30-63-00.
Ammeter
does
not
cycle
Timer
ground
open;
timer
not
Disconnect
harness
at
timer
and
("flicker")
each
90
seconds,
cycling.
check
ground
connection
with
ohmmeter
from
Pin
A
(12V)
or
TerminalG
(24V).
Timer
contacts
welded
together
Test
timer
per
Section
3063-00.
If
(caused
by
short
in
electn’cal
timer
is
faulty,
repair
or
replace
it,
system).
but
insure
that
short
causing
original
failure
has
been
located
and
corrected.
Ammeter
flickers
between
90
Loose
connection
between
Trace
win’ng
from
power
source
to
second
phase
periods.(l2V)
aircraft
power
supply
and
timer
timer
input.
Insure
that
good
input,
electrical
contaets
are
made
at
each
connection
in
the
circuit
30-61-02
OLDWILLWAYNE