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Model 3455A
2. Plug the Inguard/Outguard
Service Cable
from one instrument's outguard connector (A1J7)
to the other instrument's Inguard/Outguard cable
assembly (W1). 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
TROUBLESHOOTING
Section VIII
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 3455A
and
also the working section.
NOTE
Make sure the power supplies of the in-
operative 3455A 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 3455A 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 8-45. Inguard-Outguard Connections.
8-198. Service Group Summary.
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
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Table of Contents
Troubleshooting
