Raytheon Beech Baron E55 - Page 687

Raynleon
nircraft
Company
BARON
55
AND
58
SHOP MANUAL
STROBE
LIGHT,
BULLOCK
UNIT
The
system
consists
of
a
solid
state
power
supply
unit,
a
circuit
breaker switch
on
the
instrument
panel,
a
shielded
power
cable
and
a
single,
ventral-mounted
xenon
gas
light.
System
operation
is
based
on the
capacitance
discharge
principle.
A
DC
converter
steps
up
the
aircraft
battery voltage
to
approximately
400
volts
to
charge
the
capacitor.
The
trigger
circuit
consists
of
a
unijunction
oscillator
and
a
silicon controlled
rectifier
which
applies
a
pulse
of
negative
voltage
to
the
trigger
transformer
in
the
lamp.
The
trigger
transformer
produces
an
ionization
voltage
of
approximately
4,000
volts
to
ignite
the
xenon
gas
in the
lamp.
As
the
lamp ignites,
the
energy
stored in the
capacitor
is
discharged
through
the
lamp
to
produce
a
peak light
intensity
of
over
a
million candle
power.
When
the
capacitor
voltage drops
below
50
volts,
the
lamp
will
go
out
and the
capacitor
begins
recharging
for
the
next
cycle,
System
operational
cycle
will
repeat,
until the strobe
light
is
turned
off,
at
a
flash
rate
of
45
flashes
per
minute.
TROUBLE ANAL
YSIS
Whenever
trouble
occu
re,
check
all
primary
power
lines,
external
circuit
elements,
fuses
and
wiring
for
a
malf unction
before
troubleshooting
the
strobe
light
system.
System
electrical failure
may
be
traced
to
any
of
three
general
areas:
power
unit,
lamp
assembly
or
wiring.
A
quick
method
of
isolating
the trouble
source
is
to
remove
the
lens
of
the
xenon
lamp
and
test
the
lamp. Inspect
the
lamp
to
see
if
it
is
broken
or
loose in
its
socket. If
the
lamp
is
intact,
use
a
DC
voltmeter
to
check
for
approximately
350 volts
at
the
top
of
the
lamp
with
the
system
turned
on.
The
rate
that
the
voltage
peaks
should
be
between
40
to
55
times
per
minute. If
no
voltage
is
present,
the
fault is
probably
located
in
the
power
unit.
TROUBLESHOOTING
POWER
UNIT
Disassemble
the
power
unit
by
removing
the
screws
securing
the end
plates
to
the
power
unit.
Remove
the
end
plate
which
has
the
power
plug
and
slide
the
bottom
heat
sink
forward
until
it
can
be
separated.
The
large
capacitor
may
be
attached
to
the
rear
end
plate
by
thermal
epoxy
for
efficient
heat transfer
and
care
should
be taken
to
avoid
breaking
this
bond.
The
upper
heat sink
(with
transistors
mounted
on
it)
can
be
slid
forward,
exposing
the
component
board
and
capacitor
bracket.
Remove the
nuts
securing
the
board
to
the metal
bracket
and the
component
board
will
be
completely
accessible.
CONVERTER
TROUBLESHOOTING
a.
if
the fuse
keeps
blowing,
check
transistor
21\13055 for
a
possible
short.
It
will
be
necessary
to
remove
the
emitter
wire,
and
unsolder
the base wire
before
an
ohmmeter check
can
be
made.
Many
times
only
one
transistor
will
fail.
Failure
of
Capacitor
CI
will also
cause
the fuse
to
blow.
I
b.
If
the
converter
won’t
start
when
voltage
is
first
applied,
a
small current
kick
is
noted
and then
no
current
is
drawn;
look for
a
poor
solder
joint
in
the
starting
circuit,
R2
2.7K
and
R1 82 ohms.
The
converter
may
be
started
by
applying
about
2
volts
to
the
junction
of R I
and R2.
c.
Low
or
no
output
voltage,
but
converter
operates
otherwise.
Using
an
ohmmeter,
look
for
a
shorted
diode
in
the
bridge
circuit.
In
extreme
cases,
the
transformer could
have
a
shorted
winding.
As
a
check,
disconnect
a
lead
from
the
transformer
secondary,
if
the
current
remains the
same,
the transformer
should
be
replaced.
d.
Low
output
voltage
can
be
the
result
of
a
faulty
capacitor
C2.
Check
by removing
the
positive
lead from
the
capacitor.
e.
Low
voltage
coupled
with
very
slow
voltage buildup
can
be
traced
to
a
faulty
transistor
2N3055.
An
ohmmeter
check
will
indicate
which
transistor
has
failed.
Select
replacement
transistors
having
a
collector
to
emitter
resistance
of
100
ohms
minimum.
Dec
31/03Page
90
SECTION 13