Section
V
5.72.
TBOUBLESHOOTING.
5-73.
This
portion
of
Section V
contains infoflnation and
procedures
desigled to
assist in thc isolation of ntalfunc-
tions. The information prescntcd
is based on
a systematic
analysis of
the
instrument
circuits and, if
followed,
will
rninirnize
troubleshooting
time.
5-74. Guidelines.
5-75. Before troublcshooting the 35754, obscrve the fol-
lorving
guidelines:
a. Pcrforrn thc adjustrnents
outlined in
Paragraphs
5-25
through 5-48. Some
apparent
rrallunctions
oan bc cor-
rected
by thcse adjustmcnts or the inability to obtain
correct
adjustnrent
will often
reveal the source of trouble.
b. Check
thc
power
supplies
(Pafagraph
5-27) before
troubleshooting
other
sections.
c.
Check
lor
burned or loose
cornponents,loose
connec-
tions or
any other obvious
condition that might
be a source
of
trouble.
5-76. Symptoms.
5-77. Obtair as mrny front
panel
symptoms
as
possible.
Check the
perforruance
ol the 3575A and obtain the
lcrllorving failure information :
a. Does
the trouble affect
arnplitude readings?
If
yes,
disegard
phase
and
refer
to the Arnplitude
Troubleshooting
Tree
(Figure
5-8). The
Amplitude Troubleshootilg
Tree
will help
isolate the trouble
to a stage or component or will
Iead to the Digital
Parel Meter
Troubleshooting
Tree
(Figure
5.9).
b. Does
the trouble affect
pllase
readillgs
only'! lf
yes,
refer
to the Phase Troubleshooting
Tree
(F'igure
5-10).
The
Phase
Troubleshooting
Tree
will help
isolate the trouble
to
a stage or
component or will lead
to the Phase
l,ogic
Troubleshuoring Trcc
(Figurc
5-l l).
5'78. Trouhleshootinq Trees.
5'79. The iour t
rolr blc slt ooling trees, FiBure 5-8
through
5-11,
are located on fold{uts
at tlre cnd oI tl]is seotion.
Mrcn entering
a
troubleshooting trcc,
always start
at the
point
labeled
"START".
Do not attempt
to start
in the
middle of
a tree. Chccks outlined
in
each
troubleshooting
tree
will
lead to anothcr
troubleshooting
tree or to one of
the
following:
"Probable
Cause"
"Recheck
Symptoms"
5-80.
'Probable
Cause." The
"Probable
CaLrse" inftrr-
mation
only indicatcs rhe urost
likell
lailurc areas and
dcsignatcd
components
are not neccssarily
the exact
cause
of
trouble.
The "hobable
Cause" infonuation
should bc
s-t 8
Model
3575A
used
in conjunction
with the voltages
and waveforms
on
the
schematic
diagrams
to
further pinpoint
the source
of
trouble.
5-81.
"Recheck
Symptoms." The "Recheck
Symptoms"
blocks indicate
that
preceeding
checks do not reveal
any
specific malfunction. When
confronted with
a "Recheck
Symptom"
block, recheck
the
performance
of the
instru-
ment
to verify
that the original
symptom is still
present.
If
the original
symptom
persists,
repeat
the checks outlined
in
the
troubleshootillg
trees while watching for
marginal
indications.
If the trouble still
cannot be localized,
trouble-
shoot
using the
yoltages
atd waveforms
on the
schematic
diagrans.
Contact
the
nearest
-hp-
Servicc Office or
(bstomer
Service
facility
if assistance is required.
5-82. Measurement
Conditions.
5-83.
The voltages
and waveforms
shown on
the scllentatics
and
troubleshooting
trees were obtained
with a I V
rms
(+
6 dBV),
I
kllz
sine
wave applied
to
both
inputs.
If
symptoms
do not
appear with
2
Vrms,
I kHz
inputs,
troubleshoot
using
inputs
that
produce
symptoms.
Keep
thc
input level
as high as
possible
and
the input
frequency
as close
to I
kllz
as
possible.
Note
that some of
the
waveshapes
and voltages
may differ when
inputs other
thalr
2
V
mrs, I kllz are
used.
5-84.
Control Settings.
5-85. When
using
the troubleshooting
trees with
2
V
rms,
1 kllz inputs,
the 3575A
controis
should
be set as follorvs;
DISPLAY
....AMPLITUDE
(for
arnplitude
problem)
DISPLAY
...... ...PHASE
(for
phase probtem)
AMPLTTUDE
FUNCTION.., ......
. A
(or
as
specified)
Voltage
Range
. 0.2 mV
-
2 V
(both
channels)
FREQUNECY
RAh\GE . l0 tlz
-
100 kHz
PHASEREFERENCE,....
-......+A
(or
as specified)
5-86. Power Supply
Troubleshooting.
5-87.
The
3575A
contains six major
power
supplies that
lirrnish
regulated voltage
to thc
various
assemblies through-
out
the
instrument.
The raw
supplies
a-re located
on the
Power
Supply
Mother
Board,
A15, and
the regulator
circuits for
these
supplies
are located on
the Power
Supply
Asscmbly,
Al,+. ln
addition,
the IJ)g
Converter
Assemblies,
A3
and A4, contain
separate
regulator
circuits
which supply
+
2
Vdc
to the Hybrid
lrg
Amplifiers.
The
+
2
V regulators
receive preregulated
voltage from
the
+
3.8 Vdc
supply on
A14.
5-88.
Before
troubleshooting
the 3575A, perform
the
+
12 V
Reference
Adjustnent
(Paragraph
5-25)
and check
the
power
supply
voltagcs
as outlined
in Paragraph
5-28.
TBOUBLESHOOTING
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