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Section
V
f.
Replace
the top
cover and two
phillips
head
screws
in
photochopper
block.
g.
Reconnect
the cable to pins
2,
3,
4
and
5.
The
larger black lead
in
the cable
connects
to pin
2.
Other
leads
identifications
are as
follows:
White
lead
to
pin
3
Green
and red
lead
to
pin 4
Thin
black lead
to pin
5.
h.
Replace chopper
amplifier board.
5-43.
SERVICING ETCHED
CIRCUIT
BOARDS.
5-44.
The
-hp-
Model 3400A
has
five
etched
circuit
boards.
Use
caution
when removing them
to
avoid
damaging mounted components.
The
assembly and
-hp- Part No. are
silk
screened on
the interior
of
the
circuit
board
to identify
it.
Refer
to
Section VTI
for
parts
replacement and -hp-
part
number
information.
5-45.
The
etched
circuit
boards are a
plated-through
type.
The
electrical
connection
between
sides
of
the
board
is
made
by a layer
of
metal
plated
through
the
component
holes.
When
working on
these boards,
observe
the following
general
rules:
a.
Use
a low-heat
(25 to
50 watts)
small-tip
soldering iron
and a small diameter
rosin
core
solder.
Model 3400A
b.
Circuit
components can
be
removed
by plac-
ing the
soldering iron on
the
component
lead
on
either side
of
the
board and
pulling
upon
lead.
If
a
component
is
obviously
damaged,
clip
leads as close
to
component
as possible
and then remove.
Excess
heat
can cause
the
circuit
and board
to
separate or cause
dam-
age
to the
component.
c.
Component
lead hole
should be cleaned be-
fore inserting
new
lead.
d.
To
replace components, shape
new
leads
and
insert
them
in
holes.
Reheat
with iron
and
add
solder as required
to
insure a
good
elec-
trical
connection.
e.
Clean excess
flux
from
the
connection and
adjoining area.
CAUTION
UUUUUUUMUU
V
WATER,
COMMERCIAL
CLEANERS,
OR DETERGENTS
WILL CAUSE PER-
MANENT DAMAGE TO PHOTOCHOPPER
ASSEMBLY
A5.
To
avoid surface contamination
of
the print-
ed
circuit,
clean with
weak
solution
of
warm
water and mild
detergent
after repair.
Rinse
thoroughly with clean water.
When
complet-
ely dry,
spray
lightly
with
Krylon
(#1302 or
equivalent).
Table
5-7.
Factory
Selected
Components
DESIGNATOR
FUNCTION
VALUE
LOW
NORMAL
HIGH
C205
Adjust low frequency
(10
Hz) response.
100
ixF
(selected)
C302
Adjust high frequency
(10
MHz)
of
Second
Attenuator
on
0.
001
V
and
1
V
ranges.
5
pF
12
pF
15
pF
C304
Adjust high frequency
(3
MHz
to 10
MHz)
of
Second
Attenuator on
0. 3
V
and
300
V
ranges.
24
pF
39
pF
C305
Adjust high frequency
(10
MHz)
of
Second
Attenuator
on
0.
01
V
and
10
V
ranges.
5
pF
12
pF
C427
See
NOTE
on schematic.
200
nF
(selected)
---
R3
Adjust
the
range
of
R4
(CAL).
820
n
1200
ft
2.
16
kfi
R8
Adjust
the
range
of
R7
(1/10
SCALE
ADJ).
390
ft
(selected)
R419
Adjust voltage
at
collector
of
Q406
(no signal
input,
1.5
to
2.
5
Vdc).
270
300
5-16
01768-3

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