HP 3455A - Page 127

Model 3455A
TROUBLESHOOTING
Section
VIII
2. Plug the
Inguard/Outguard
Service Cable
from one
instrument’s
outguard connector (A1J7)
to the
other instrument's
Inguard/Outguard
cable
assembly
(Wl). The
instruments are
now effec-
tively half-split
with
one
unit’s inguard
section
connected
to the other unit’s
outguard section
(see
(Figure
8-45)
3. Turn
on the
instrument with the
active in-
guard section and
then turn on the
instrument
with the
active outguard section. The
display from
the unit
with
the
active outguard
should become
energized. If the
instrument
malfunction has
disappeared, then
the portion of
the
defective
in-
strument used
(inguard or
outguard) is
working.
Consequently, if the
malfunction remains, the sec-
tion
of the
defective instrument
used is in-
operative.
4. The
defective section can be
verified by
reversing the
Inguard/Outguard
Service Cable
and
repeating steps 2 and 3.
Make sure the
3455A’s are turned off,
when
switching
connec-
tions.
Reversing
the
service cable should
verify the
defective
section
of the
inoperative 34SSA and
also the
working section.
NOTE
Make
sure the
power supplies
of
the in-
operative 34S5A
are
good.
b. Once
it has been
determined in
what section the
defective
is
located (Inguard or
Outguard), the correct
Service
Group
can be used for
component isolation (see
Paragraph
8-198
for a
summary of the
Service
Groups).
8-197. If an extra 34SSA or an
Inguard/Outguard Ser-
vice Cable is not
available, use the method
described in
Service Group H,
Figure 8-H-2. This
method is not as
complete as the
half-split technique.
Figure B-4S.
Inguard-Outguard
Connections.
8-198. Service Group Summarv.
8-199.
The
following is a summary
of
the
various ser-
vice groupsand
should be used in
conjunction
with
Table
8-3.
a. Turn-On
Circuitry
(Service
Group A):
Turn-on
failures
show
up as an
inoperative front panel
"and” a
blank display, at
turn on. Use this
service
group
if both
of these symptoms are
observed. The turn-on
circuitry is
working
properly, if there is any
indication on the
display and the
front panel is
operative.
b. Auto-Cal
and DC
Troubleshooting
(Service
8-37