Servicing Etched Circuit Boards; Factory Selected Components - HP 3400A Operating And Service Manual

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