Mooney M20K - Page 102

SERVICE
AND
MAINTENANCE
MANUAL
M20K
MOONEY
AIRCRAFT
CORPORATION
12 VDC
r2
UDC
i
LP~P
DS-x
I
R89
F1BB
11Bb2~r
9r~
DIMOUTPUT
RB5
R98
PB7
xtnPUt
CR3~
2BUDC
~Y4DsS
R91
I
,I
U9
CR35
I i
DI~INPUT
471(
RB1
~-i,
915
I
yl,.-nclYI1
CR36
b.D((
213819
DI~LcBmS
1(4SIS
TeST+
FIGURE
8
T/PICAL
POSITIVE.APPLY
W/DIM
9.0
TYPICAL
POSITIVEAPPLYW/DIM
A
typical
Positive
Apply,
Dimmable
circuit
is
shown
in
Figure
8.
This
channel
is
designed
to
accept
a
+28
VDC
signal
to
illuminate an
indicator
channel
and
Drovide
for
dimming
of that
channel,
as
well.
Dimming
is
accomplished
in
a
manner
similar
to
that
descn’bed
for
low
fuel
channel
above.
The
input,
XINPUT,
is
CR
313
applied
through
CR35
and
R84
to
drive
015
into
YINPUT
saturation
and
light
DS-X.
TEST+
is
applied
through
CR36
and
R84
to
also
dn’ve
015
into
saturation
and
INSb(jg
light
DS-X.
These
5
channels
may
be
dimmed
by
depressing
the
DIM
switch
to
dim
the
active
channels.
CR37
DS-Y
Depressing
the
TEST
switch
returns
the
active
dimmed
TESTt
7327
channels
to
bright.
V\hen a
dimmed
channel
is
extinguished
and
then
reactivates
a
will
readivate
INSbbS
bright.
Each
channel
to
be
dimmed
is
dn’ven
by
a
transistor,
in
this
case
015
which
returns
the
lamp
to
ground
through
two
parallel
paths.
The
path
to
provide
a
dim indication
is
through
resistor
R85
which
reduces
Y
the
brilliance
of
the
lamp.
In
the
bn’ght
mode
R85
is
shorted
by
014
and
CR34
which
provide
a
low
impedance
path
to
ground.
Transistor
014
is
controlled
in
conduction
by
a
latch
composed
of
U9
and
its
F
IGURE
9
associated
resistors
R86,
R87,
R88,
R89,
R90
and
R91
as
well
as
the
signals
DIMBIAS
and
DIMINPUT.
If the
GJ
O
D
I
channel
is
active
DIMINPUT
willbeneargroundand
YP1CRZ,
POSITIVE
APPtY
with
DIMBIAS
near
3
VDC,
the
output
of
U9
will
be
high,
thus
driving
014
into
conduction.
When
the
DIM
Switch
is
depressed
momentarily,
DIMBIAS
goes
high
to
12
VDC
and
U9
switches
its
output
low
and
latches
through
R87.
This
low
output
removes
the
dn’ve
from
014
and
DS-X
dims.
When
the
TEST
Switch
is
depressed
momentan’!y,
DIMBIAS
goes
Low and
U9
switches
its
output
high,
latches
through
R87,
and
+28
VDC
s~nal
to
illuminate
an
indicator channel,
but
drives
014
into
conduction.
When
the
channel
does not
provide
for
dimming
of
that
channel.
deactivates,
015
opens
the
retum
to
ground
and
DIMINPUT
n’ses
which
retums
latch
U9
to
a
high
output
The
input,
YINPUT,
is
applied
through
CR38
to
light
state.
DS-Y.
TEST+
is
applied
through
CR37
to
also
light
DS-Y.
10.0
TYPICAL
POSITIVE
APPLYWIOIDIM
A
typical
Positive
Apply,
Non-Dimmable
circuit
is
shown
in
Figure
9.
This
channel
is
designed
to
accept
a
24-39-06
23
OLDWILLWAYNE