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Section
VIE
Model 1821A
c.
If
a
component
is
obviously
damaged
or
faulty,
clip
the leads
close
to the
component
and
then un-
solder
the
leads
from
the
board.
d.
Large components such
as
potentiometers
may
be
removed
by rotating
the
soldering iron
from
lead
to
lead
and
applying steady
pressure
to
lift
the
part
free
(the
alternative
is
to clip
the
leads
of
a
damaged
part).
e.
Since
the
conductor portion
of
the
etched
circuit
board
is
a
metal
plated surface
covered
with solder,
use care
to
avoid overheating
which causes
the
con-
ductor
to
lift
away from
the
board.
A
lifted
conductor
may
be
cemented back
in
place with
a
quick-drying
acetate
base
cement
(use
sparingly)
having good
insu-
lating
properties.
Another method
of
repair
is
to
solder
a section
of
copper wire
along
the
damaged
area.
f.
Clear
the
solder
from
the
component
hole
be-
fore inserting a
new component
lead.
Heat
the
solder
in
the hole,
remove
the iron,
and
quickly insert a
pointed non-metallic
object,
such
as a toothpick.
g.
Shape
the
new component
leads
and
clip
to
proper
length.
Insert the leads
into
the holes,
apply
heat
and
solder (preferably on
the
side opposite the
component).
Table
8-1.
Schematic
Diagram
Notes
Refer
to
MIL-STD-
15-
lA
for
schematic symbols
not listed
in
this table.
L
a-
p/o
cw
N.C.
V
<7
*
=
Etched
circuit
board
=
Front panel
marking
=
Rear
panel
marking
=
Front
panel control
=
Screwdriver adjustment
=
Part
of
=
Clockwise
end
of
vari-
able resistor
=
No
connection
=
Waveform
test
point
(with
number)
=
Common
electrical point
(with
letter)
not
necessarily
ground
=
Single pin
connector
=
Pin
of
a plug-in
board
(with
letter
or
number)
=
Primary
signal flow
=
Secondary
signal
flow
=
Optimum
value selected
at
factory,
average
value shown; part
may
have been
omitted.
0
I
. 1 .
=
Field
effect
transistor
(N-channel)
=
Breakdown
diode
Tunnel
diode
Step
recovery
diode
=
Circuits
or
components drawn
with
dashed
lines
(phantom)
show
function only
and are
not
intended
to
be complete.
The
circuit or
component
is
shown
in
detail
on
another schematic.
Unless otherwise
indicated:
resistance
in
ohms
capacitance
in
picofarads
inductance
in
microhenries
Wire
colors are given by
numbers
in
parentheses
using
the
resistor color
code
[
(925)
is
wht-red-grn
],
0
-
Black
1
-
Brown
2
-
Red
3
-
Orange
4
-
Yellow
5
-
Green
6
-
Blue
7
-
Violet
8
-
Gray
9
-
White
Switch
wafers are
identEied
as
follows:
IF
I
3F
3R
IF,
IR
2F
2R
8-2
02591-2
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