Troubleshooting Display Messages - IBM 6400 Maintenance Information Manual

Troubleshooting Display Messages

If a fault condition occurs in the printer, four things happen:
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The LCD displays two kinds of printer conditions:
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DANGER
<3> Hazardous voltages are present in the printer with the
power cord connected to the power source. Switch off
printer power and unplug the printer power cord before
proceeding.
<4> Do not connect or disconnect any communication port,
teleport, attachment connector, or power cord during an
electrical storm.
<5> Power off the printer and disconnect the power cord before
connecting or disconnecting any communication port,
teleport, or attachment cable connector.
The Attention indicator on the operator panel flashes on and off.
If enabled, the audible alarm sounds. (Press Stop to silence the alarm.)
A message describing the fault condition appears on the LCD.
Certain Unit Check conditions (see below) are automatically recorded in
the error log. The error log is a buffer in NVRAM that stores up to 50
messages as a list. The most recent message is stored at the top of the
list, the oldest message at the bottom of the list. If more than 50
messages occur before the log is cleared, the oldest messages are
deleted, so the log never contains more than 50 messages. You can print
the error log and clear it. (See page 135.)
An Attention condition halts printing until the operator replenishes
supplies, clears paper jams, corrects a problem of communication
between the printer and host computer, etc.
A Unit Check condition is a failure detected by self-test and fault circuitry.
Unit check conditions are either recoverable or unrecoverable .
Recoverable unit check conditions are errors detected in the
electromechanical print mechanism that may be temporary and
correctable by cycling power. The printer tries a number of times to
correct the condition before posting the message to the operator panel.
The first thing to do in such cases is to power the printer off, wait 15
seconds, then power the printer back on. If the message reappears,
classify the check condition unrecoverable.
Unrecoverable unit check conditions are "hard" failures such as
overcurrent, component failure, or microcode failures that prevent printing
until the conditions are corrected. Unrecoverable conditions require that
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