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g
CJ°'
N
,
.
Instrument op
er
-
ating
but meter
indicator action is
unstable or
erratic
(con
t
'
d)
.
·
416A004-l
10/26
/
55
Seria:l 7() a~d abo~e
Trouble
in instrument
( cont
1
d
}o
Traub le
in
input
cir
-
cuit (incident
or
re-
flected
).
5
.
(con
1
d)
capacitors C27 and C41
,
as described
in
Electrical
Full Scale Adjustment
.
a. If
v
oltages at C27
and/or
C41
are
not
at
levels
specified
i
n Electrical Full
Scale Adjustments
,
trouble
is in in-
put circuit
(s
ee
steps 6
and
7).
b
.
If voltages at
C27
and
C41
are at spec-
ifie
d le
vels
9
trouble
is in
a subse-
quent
circuit (see steps 8 and 9),
6
.
Under a test
conditi
on of
100% reflec-
tion (attenuator #2 at
0 db)
:
a.
From
pin
3
of V2 to
ground
,
AC
voltage
should be
approximately
0
035
volt.
If
.
035
volt
±10%
is
not
obtained
,
trouble probably
is
in
the
incident
channel
input cirucit
:
(
1) Check
Vl
and
V2.
(2)
Check DC
voltages;
levels should
be
within ±10%
of those
shown
in
the schematic
.
b. From
the
output
side
of C25 to
ground,
AC
voltage
should be approximately
.
25
volt.
( C25
is
mounted on resistor
board RB 1 [Figs
.
21 and 22]
.
The C25
output connection
is
made at the term-
inal
on the
inner edge
of RB 1 [he side
nearest the
vacuum
tube socket!]
.
) If
.
25 volt ±10%
is not obtained
,
trouble
probably
is
in the
reflected channel in
-
put circuit:
( 1)
Check
V2
,
V3, and
V4
.
( 1) Replace
Vl or
V
2
,
if
defective
.
(2)
Check resistors
and capacitors
of stage in
trouble. Re
-
place any
not
within
toler
anc
es
given in Table of
Rep
lac
eab le
Parts
.
( 1) Replace
V2
,
V 3
,
or V4,
if
defe
c-
tive.
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