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Mod€ls
461A/462A
A
5-29. Reg"rdless which
type ot
erched-circuit
board
-
is
usFd. lhe
loltowDs rules
should
be
followFd:
a.
Avoid applying
exc€ssive
heat
when soldering
on
the
circuit board.
Use
a
3?
to
50
watt pencil
tip
soldering iron.
b.
To
remove
a
damaged
component,
clipthecom-
ponent
lead near the
component.
Then
apply
heat
and
remove the lead
with
a
straieht
uward
motion.
c.
Use
a
toothpick
to free
eyelet
of solder
before
instauing
a
nw
component.
d.
Solder
flom the
conductor side of the board
to
insure
good
connections
betw€en
the eyelet
and the
conductor.
5.3
O.
IROUBLISHOOTING
PROCEOURE.
a.
Start
v,/ith a thorough
visual
inspection.
Look
Iorburned
o'rt
or loos€
components,
loose
comections,
or
any
other
similar
condition
which suggests a source
of
trouble.
b.
Inspect
the
test
setupbeingusedwhen symptoms
of
mauunction
were
obselved
tobe
cetain
the
source
of
trouble is
not
exlernal
to
Amplifier.
Pamgraphs
5-29
to
5-30
c.
Check pon
er supply
as
outlined
in Paxagraph
5-
22.
d.
Check
dc levels identilied
on the
schematic
diagnm,
Figure
5-13.
e.
Pedormprocedure
outlined
in Pangraph
5-23,
f.
UsinganAc voltm€ter
Ghp-
Moder
400L),
check
the
gain oI
transistors
Q4
thru Q9, typicaUy
I
db
per
NOTE
Gain of Q4
is
controlled
by the
!?lue
of R18+
(4.
?
to
10
ohms).
g.
RotateModel
461A
GAIN
control
to
20
db
to de-
termiDe
if
marunction
is
isolat€d
to
Attenutori
Amplitude
of
signal
at
base
of
Q3
should decrease by
h.
TheR-L
feedback
Networkand
tlansistors
are
responsible
for
the high
lrequency
perlormance
and
should
be checked iJ
difficulty is
encountered at high
i.
Perform Calibration
and
Pe?formance
Check
Procedures
alter repair is
completed.
01358-2
5-9/5-10
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