Agilent Technologies 78581B, Installation And Service Manual

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Troubleshooting Resources, Tools, and Equipment
3-12
Miscellaneous Items
The preceding troubleshooting procedures provide a general methodology
which captures the majority of electronic hardware failures. However,
several problems can be identified which will not be caught, and are
elaborated below.
a. Cable checking was not always explicitly stated as a possible problem
source. However, cables should be checked for continuity and shorts
when suspect using the cable verification procedure specified on page
3-13.
Cable intermittents: Moving cables with intermittent connections can
cause symptoms to disappear or reappear unpredictably.
b. Excessive noise on one branch can impair communications on all
branches. This can occur if a raw cable with no wall box connector is
wired to the ACC and the raw ends are shorting to each other or to
conduit. This can also occur if the wall box connections are loose or
LDCs are loosely connected. The FIRE AXE LED will usually be
illuminated. Instruments may disappear and reappear on the Network
Test, or their status may change from 001 C. Noisy branches can be
identified by low voltage levels below ground and high levels above 5V.
Proceed with cable verification procedure specified on page 3-13.
c. Hospital ground may not meet the system specification. If this is
suspected, refer to the ground check procedure on page 3-13.
d. The hospital has installed cables (other than Agilent Technologies SDN
or Agilent Technologies Analog cables) in violation of Agilent
Technologies distance and shielding specifications. The new cables are
causing interference.
e. Overloaded system — Constant or intermittent overflow: In an
overloaded system some branch will be transmitting at the end of the
32 ms poll cycle. All higher numbered branches get no chance to
transmit. The OVERFLOW LED will be illuminated or flickering in the
ACC. True chronic overflow is highly improbable with the current set
of products in a fully loaded system (24 monitor/terminals, 6 ICs, and
PDMS).
Recap of Troubleshooting Procedures:
STEP #1: Review System Architecture
STEP #2: Examine System — gather symptoms
• Determine if the problem involves SDN connected equipment
• Error codes and INOPs
• ACC LEDs