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i
O'
UJ
Symptoms
Instrument oper
-
ating
but meter
indicator action is
unstable or
erratic
(cont
~
d)
.
Possible Cause
Trouble
in input cir
-
cuit
(incident
or
re
-
fleeted)
(cont'
d)
.
Defective
filter.
Test Procedure
6
.
b
(cont'd)
(2)
Check DC
v
olta
ges;
levels should
be
with
i
n
±10% of those shown in
the schematic
.
7
.
If
voltages
at V2 and C25 outputs are
correct and voltages at
C27
and
C41
incorrect,
probably one of the filters
is defective.
a.
To test
F
ilt
er
1
,
disconnect
the
re
-
flected
input cable
,
and leave the
i
n-
cide
nt inpu
t
cable (Fig. 18). With test
vo
lta
ge
incoming
,
the
meter should
i
nd
i
cate steadily on zero.
If
Filter
1
i
s
defectiv
e
,
i
ndicator
will
be
v ery
un
-
stable
around the
0
point
.
b
.
To test
F
ilter
2
,
both input
cables
should be
connected
.
Under
conditions
of
100%
reflection
,
if a
low
reflection
voltage
i
s
ind
icate
d by
the
instrument
meter
,
Filter
2 is
defective.
c. Before
re
placing the filters
,
check
the
defective
filter
for
a
poss
ib
le open
in
the wirrng
.
The filters
are identified
in
F
ig.
20
.
(Before the cover
of Filter
1
can
be
removed,
the tuni
n
g
eye
[V9]
must
be
freed
from
its
holder
and
moved out
of
the way.)
Less
than
25 ohms
should
be measured
:
Filter 1 From output (outs
i
de terminal)
of R
11 to ground
.
Across Rl2
Filter 2 From input to
ground,
(This
measurement may be from the
output side of C25 to
ground.
[Qutput terminal of C25 is iden
-
tified in step 6b
,
abovg )
dAoq-e pu-e
6L
1-e~.rds
SS/92/01
I
-:
1700V<Ht
Remedies
(2)
Checkres
i
stors
and
capacitors
of stage
in
trouble
.
Replace
any
not
within
tolerances
given
in
Table of
Replaceable Par ts.
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