IBM 6500-V20 Maintenance Manual - Page 42

Chapter 1 Troubleshooting Display Messages Troubleshooting Display Messages If a fault condition occurs in the printer, three things happen: • The status indicator on the operator panel flashes on and off. • 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 non- volatile memory (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. The list can never contain more than 50 error messages, so the bottom message drops away if the count reaches more than 50 error messages before the log is cleared. You can both print the error log and clear it. (See page 213.) The LCD displays two kinds of printer conditions: • 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 unit 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 the printer be powered off and the condition corrected before powering the printer back on. Display Messages Find the message in the Message List below and follow the suggested procedure. After correcting an error, press the START key to clear the message. If an error is not cleared, the printer will try to print again but will display the error message until the error is cleared. 42