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Troubleshooting
the
A12
Controller
Troubleshooting
the
A12
Controller
Only
the
+5
V
supply
has
to
be
present
in
order
for
the
A12
controller
to
operate
.
This
supply
is
generated
on
the
A12
from
+8
V
unregulated
supply
(A10TP101-1)
of
the
A10
power
supply/driver
.
If
the
+8
V
unregulated
is
not
present,
refer
to
the
power
supply
section
of
A10
power
supply/driver
troubleshooting.
The
A12
uses
the
+25
V
supply
for
attenuator
switching
drive
.
The
+5
V
supply
is
used
for
attenuator
switching.
When
the
spectrum
analyzer
is
turned
o,
this
supply
sets
the
input
attenuator
to
70
dB
.
This
protects
the
RF
input
of
the
module
from
any
high-power
signals
applied
while
the
spectrum
analyzer
is
o.
The
supply
is
also
used
to
disable
the
output
from
the
ROM
A12U7
during
power
down.
The
A12
controller
receives
information
from
the
HP-MSIB
master
module
and
acts
upon
it
accordingly
.
The
controller
is
responsible
for
the
following
functions
under
the
control
of
the
master
element:
Attenuator
settings
Last
converter
step
gain
on/o
2nd
converter
V
CO
on/o
RF
input
path
switching
IF
input
selection
to
last
converter
321.4
MHz
IF
output
selection
on
last
converter
Track
and
hold
Band
information
(A0,
A1)
Servicing
of
status
detectors
Except
for
the
servicing
of
status
detectors
(error
reporting),
the
controller
does
not
respond
to
any
stimulus
from
the
module
itself.
T
roubleshooting
4-47
Summary of Contents for 70908A
Page 7: ...Servicing at a Glance vi ...
Page 19: ......
Page 44: ...Figure 2 1 Main Menu Softkeys Module Veri cation Software 2 19 ...
Page 45: ...Figure 2 2 Mass Storage Menu and Parameter Menu Softkeys 2 20 Module Veri cation Software ...
Page 47: ...Figure 2 4 Test Menu Softkeys 2 22 Module Veri cation Software ...
Page 55: ......
Page 61: ......
Page 94: ...Troubleshooting the A3 SYTFMD Figure 4 5 Discriminator Output Waveform Troubleshooting 4 33 ...
Page 125: ......
Page 139: ......
Page 205: ......
Page 209: ...Test 01 Flatness Figure 8 2 Equipment Setup for Test 01 Flatness 8 4 Module Veri cation Tests ...
Page 267: ......
Page 271: ...Front Panel Figure 9 2 Front Panel Removal Replacement 1 of 2 9 4 Replacing Major Assemblies ...
Page 272: ...Front Panel Figure 9 3 Front Panel Removal Replacement 2 of 2 Replacing Major Assemblies 9 5 ...
Page 274: ...Rear Panel Figure 9 4 Rear Panel Removal Replacement 1 or 2 Replacing Major Assemblies 9 7 ...
Page 275: ...Rear Panel Figure 9 5 Rear Panel Removal Replacement 2 or 2 9 8 Replacing Major Assemblies ...
Page 284: ...A3 SYTFMD Figure 9 10 A3 SYTFMD Removal Replacement Replacing Major Assemblies 9 17 ...
Page 294: ...A7 2nd Mixer Figure 9 17 A7 2nd Mixer Removal Replacement Replacing Major Assemblies 9 27 ...
Page 329: ......