IBM i 830, Repair Manual

Page: 347 / 1000

b. Set the voltage monitor to start recording at a voltage slightly higher than
the normal incoming AC voltage.
Does the system fail again with the same symptoms?
Yes No
↓
This ends the procedure.
4. Look at the recording and see if the voltage monitor recorded any noise when
the failure occurred.
Did the monitor record any noise when the failure occurred?
Yes No
↓
Perform the next INT-PIP listed in the INT-PIP column.
This ends the procedure.
5. Review with the customer what was happening external to the system when
the failure occurred. This may help you to determine the source of the noise.
Discuss with the customer what to do to remove the noise or to prevent it from
affecting the iSeries 400 system.
This ends the procedure.
INT-PIP5 External Noise on Twinaxial Cables
DANGER
To prevent a possible electrical shock when adding or removing any devices
to or from the system, ensure that the power cords for those devices are
unplugged before the signal cables are connected or disconnected. If possible,
disconnect all power cords from the existing system before you add or
remove a device. (RSFTD203)
DANGER
To prevent a possible electrical shock during an electrical storm, do not
connect or disconnect cables or station protectors for communications lines,
display stations, printers, or telephones. (RSFTD003)
Electrical noise on twinaxial cables that are not installed correctly may affect the
twinaxial workstation I/O processor card. Examples are: Open shields on twinaxial
cables and station protectors that are not being installed where necessary.
1. Check for the following on the system:
v
There must be no more than 11 breaks in a twinaxial cable run.
v
Station protectors must be installed (in pairs) where a cable enters or leaves a
building.
v
There can be only two station protectors for each twinaxial run.
v
There is a maximum of seven devices (with addresses 0-6) for each cable run.
v
There is a maximum cable length of 1524 meters (5000 feet) for each port.
v
All cable runs must be ended (terminated).
v
Disconnect all twinaxial cables that are not used.
v
Remove any cause of electrical noise in the twinaxial cables.
v
All workstations must be grounded.
Intermittent PIPs
Chapter 3. Problem Isolation Procedures (PIPs), Failing Items, and Symbolic FRU Isolation
333