Olympus
BH
‐
2
(BHT/BHTU)
Electronics
Revision
2
Page
14
of
24
Power
Transistor
Power
transistor
Q101
is
a
Toshiba
2SD867
NPN
power
transistor
in
the
old
TO
‐
3
metal
package
(see
Figure
15
).
This
part,
although
obsolete,
can
still
occasionally
be
found,
but
expect
to
pay
$20
or
more
for
it
when
you
find
it.
If
the
2SD867
cannot
be
found,
this
part
can
be
replaced
with
the
STMicroelectronics
BUX10
part,
which
is
the
same
package
style
and
is
also
obsolete.
The
NTE36
part
in
the
TO
‐
3P
insulated
case
is
a
good
substitute
that
is
available
from
Allied
Electronics
and
from
Amazon.
Whichever
approach
is
taken,
the
replacement
transistor
must
be
installed
using
suitable
mounting
hardware
which
provides
electrical
isolation
of
the
collector
tab
from
the
equipment
chassis,
and
thermal
paste
must
be
used
on
both
sides
of
the
insulator
to
enhance
thermal
conduction.
If
none
of
the
parts
listed
above
can
be
found,
look
for
an
NPN
part
with
a
collector
current
rating
of
at
least
15A,
a
collector
‐
to
‐
emitter
voltage
rating
of
at
least
100V,
and
a
current
gain
of
at
least
40,
in
a
suitable
power
package.
Figure
15
‐
Power
Transistor
Mounted
to
BHT/BHTU
Electrical
Base
(100/115V
Version)
AC
Inlet
Jack
For
safety,
always
replace
the
AC
inlet
jack
with
an
equivalent
part,
when
available
(see
Figure
16
).
Make
sure
that
the
chassis
‐
bonding
screw
for
the
ground
(middle)
terminal
of
the
jack
is
present
and
secure
and
that
the
grounding
wire
is
undamaged
before
operating
the
equipment.
This
connection
keeps
the
chassis
at
a
safe
potential
in
the
event
of
any
electrical
faults
within
the
equipment.
If
a
suitable
replacement
jack
cannot
be
located,
a
filler
plate
could
be
fabricated
to
take
the
place
of
the
AC
inlet
jack,
with
a
suitable
hole
drilled
to
allow
an
AC
line
cord
to
be
installed
with
a
strain
‐
relief
grommet.
If
this
approach
is
chosen,
be
sure
to
securely
bond
the
ground
conductor
of
the
power
cord
to
the
unit
chassis
to
maintain
equipment
safety.