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54.
Adjust
R71
to
set
the lower
peak
of
the sawtooth
wave
for
—10
mV
and
R75
to
set
the
upper peak
of the sawtooth
wave
for
+5.100
volts at
SWP/GCV
OUT
connector.
55.
Check
for
less
than
100
mV
shift
of the lower
peak
pf
sawtopith
hs^h^fpen
10
mS/1
mS
100
mS/10
mS
ranges^
56.
Set
MODE
selector
to
CONT
SWP,
SWEEP
TIME
selector
to
OFF,
and frequency
dial
to
10.
57.
Adjust
R22
to^ ^dtitaln
+5
V
±50
mV
at
SWP/GCV
OUT
cwtnectofl.
58.
Connect
a
cable
biitoffien
SWP/GCV
OUT
and
TRIG
IN
connectors.
59.
Set
SWEEP TIMi
selector
to
1
mS/100
ns; variable
tolly
MQDE
selotor to
TRjG;
frequency
range
to
X
kh^
^
^
on
dial;
OUTPUT ATTEN
to
0
dB;
vari^>le aitoitoabM*
to
fully
CW;
and waveform
to
\
.
60.
Adjust
R4
(on
mainboard)
to
set
the base
line
of the
triangle
wave
to
0 ±25
mV
at
50^2 out connector.
61
.
Set
frequency
dial tolly
CW
and frequency
VERNIER
fully
CCW,
adjust
R85
to
set
the base
line
to
0
V.
Check
that
the base
line
should remain within
±50
mV
at
all
frequency
dial settings.
62.
Set function
selection
to
^
and frequency
dial
at 10.
63.
*"
Adjust
the base
line
to
0 ±20
mV
by
R153
on
mainboard.
4.3
CORRECTIVE MAINTENANCE
If
the instrument appears to
be
operating abnormally,
and
an
investigation
of input/output connections, as
well as
a
calibration
check,
do
not
cure the
problem; follow the
trouble-shooting
procedure
outlined below. Localize the
fault
to a
specific stage
by
following the outline
in
Table
4-2.
Then
check
the
dc
operating voltages
at
the pins of
the
solid-state
devices,
and check
passive
components
with
a
high
input
impedance
ohmmeter
(power
off)
before
replacing a
suspected
semiconductor
element.
Table
4-2.
TROUBLE-SHOOTING GUIDE
Symptom
Corrective
Action
Blown
Line.Fuse
Replace FI with
a
slow
blow
fuse of
the proper amperage.
If
fuse
blows
again,
check
the
following:
a)
Q45
or
Q47 may
be
shorted
between
the
collector
and
emitter.
b|
Q1,
Q8,
Q10,
or
Q16
on power
supply board
may
be
shorted to the heat
sink bracket.
c)
A
capacitor or
transistor
may
be
shorted.
d)
Check
for loose
wires or
solder bridges
on each
printed
circuit
board.
Power Supply
MalfunctiorK
If
there
is
a
symptom
of
power
supply malfunction,
discon-
nect
alt
wires
between
die
power
supply board to the
main
board and
sweep
board
and check
the following:
a)
All
power
supply output
voltages.
If
all
are either
too
high or
too
low, the trouble
is
probably
in
the
+15
V
supply
as
all
supplies are directly or
indirectly
referenced
to
it.
b)
Check
CR9
through
CR
12.
A
defective or incorrectly
polar-
ized
diode
will
cause the
integrated
circuits
to
latch
up.
c)
Reference
voltage
at
collector
of
Q9
should be +6.6
V
±0.3
V
with
+15
V
in
normal
condition.
No
Output
Signal
a)
Power
Supply
Malfunctions
b)
For
MODE
switch
at
CONT
position,
disconnect the wire
4-5
4/73
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