MAINTENANCE
TROUBLESHOOTING
AND
REPAIR
4D-6. VCO
PCA, A2A2
The VCO
assembly comes
with its associated
VCO
Calibration
EPROM.
This
EPROM
replaces the
old
one installed on
the Controller PCB,
A2A7.
After
installing
the new VCO
assembly,
the FM
CAL and VCO
CLAMP adjustments
should be
done.
These
adjustments
are
presented under
the Synthesizer
Adjustment
Procedure.
A plug-in
coupling
capacitor
is used to
interconnect
the VCO and
Output PCBs,
thus
eliminating
the need for a
soldering iron when
replacing this
assembly.
4D"7.
Output PCA,
A2A4
The Output
assembly comes
with
its associated Output
Calibration
EPROM.
This
EPROM
replaces the old one
installed on the Controller PCB.
After installing
the new
Output assembly,
perform the level
DAC offset, the RF Level,
the HET level, and
the FM
CAL adjustment
procedures given
in
the Calibration
Adjustment
Section of this
manual.
A
plug-in coupling capacitor
is
used to interconnect
the VCO and
Output
PCBs,
eliminating
the
need for a soldering iron
when replacing this
assembly.
If
the Generator is
equipped with the Low-Rate FM
option, then it is
necessary
to add a
jumper
around
C401 and C402 on
the
new Output assembly
before
installing it.
4D-8.
Controller
PCA, A2A7
The
Controller
assembly
comes without the three
calibration
EPROMs.
Therefore, it is
necessary
to move these
EPROMs from the old to the new
Controller.
Remember
to set
the
option
status switch. No
adjustments are required.
4D-9.
Display
PCA, A1A1
After
installing
a new Display
PCA,
the Modulation
Indicator
adjustment
should be
done. The
procedure is presented
under the Display
Adjustment
Procedure.
4D-10.
Attenuator/RPP PCA,
A2A5
The Attenuator/RPP PCA
comes
complete with the
housing, Relay
Driver PCA and
matching Attenuator
Calibration EPROM, and
comes ready to
install. The
matching
EPROM
replaces the Attenuator
calibration
EPROM on
the Controller PCA.
After the
new Attenuator
assembly is
installed, perform the
RF Level
Adjustment
procedure
on
the A2A4
Output
PCA in the Calibration
Adjustments
section
of this manual
4D-11. IEEE-488
PCA, A3A3
The IEEE-488
assembly comes complete with
panel, frame, and
connector and is ready
to
plug
in. No adjustments
are required after installation.
4D-12. Non-Volatile Memory
PCA,
A2A8
The
Non-Volatile Memory assembly
comes
ready to plug in, and
requires no
adjustment
after
installation.
4D-13.
PARTS
REPLACEMENT
An
experienced
technician
should be able to isolate the
defective component
and replace
it after reading
the information presented in
Section
3,
the Theory of
Operation and
the
troubleshooting
information
contained
in
this section. The
Schematics are
presented
in
Section
8
(Section
6
for the options) of this
manual.
Most parts
are replaced using
ordinary methods. The parts
requiring
special
attention are
the
chip
components
located
on the A2A2 VCO
PCA.
The chip
components should
be
4D-3
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