HP 8508A - Page 123

Service
ERROR
CODES
300
SERIES
Errors
in
this
series
indicate
a
problem
in
the
A3
IF
Assembly.
IF
ASSEMBLY
A3
Summary
Description
.
we
The
two
20
kHz
IF
signals
produced
by
the
RF
Input
Module,
are
passed
to
the
IF
Assembly
which
operates
under
Processor
control.
The
IF
assembly
measures
the
amplitude
of
these
two
signals
and
the
phase
difference
(B-A)
between
them.
The
results
of
this
measurement
are
expressed
as
DC
voltages,
which
are
digitised
by
the
on
board
A-D
Convertor,
for
further
manipulation
by
the
Processor
(A5).
The
IF
Assembly
also
provides
real
time
outputs
for
the
Amplitude
and
Phase
values.
Troubleshooting
the
A3
IF
Assembly
A
fault
in
the
IF
Assembly
will
be
indicated
by
an
Error
Code
display
in
the
300
series.
Check
that
the
assembly
and
all
cable
connections
are
securely
in
place
and
also
that
there
are
no
obvious
defects.
An
IF
Assembly
error
report
may
be
caused
by
a
damaged
sampler.
Carry
out
the
appropriate
adjustments
for
the
IF
Assembly,
if
neces-
sary
replace
the
sampler
assemblies
and
re-run
the
Self
Test
procedure.
Should
the
Error
Code
persist,
the
IF
Assembly
should
be
replaced
with
a
new
one.
Disassembly
and
Reassembly
Procedures
Removing
the
IF
Assembly
To
remove
the
IF
Assembly
from
the
Vector
Voltmeter:
a.
Wear
a
wrist
strap
for
ESD
protection.
b.
Remove
the
tipi
Module
from
the
instrument.
c.
Remove
the
instrument
top
cover.
"
d.
Disconnect
the
cable
connections
from
the
IF
Assembly.
e.
Remove
the
10
Pozidriv
screws
that
secure
the
IF
circuit
board
to
the
main
deck.
£.
The
IF
Assembly
can
now
be
removed
from
the
instrument.
E1089
8-13