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Service Guide ML520/521
Chapter 4 Failure & Repair Analysis
4.6.03 ALARM/LED Display Troubleshooting Tables
CAUTION:
Always check that all connectors on the printer are making good contact.
Reference
Number
Failure Description
Cause
Recommended Action
1
Space Motor Alarm
Space motor IPT does
not occur in specified
time.
Refer to RAP 02.
2
Printhead Detection
Alarm
Printhead does not
home.
Refer to RAP 03.
3
Printhead A/D Alarm
Thermistor is open or +5
vdc shorted.
Check the printhead
connection. Then
replace the main control
board the carriage cable
and the printhead.
4
Printhead Gap Alarm
Self adjustment was not
successful.
Check the printhead
connection. Then
replace the main control
board the carriage cable
and the printhead.
5
Printhead Data
Transfer Alarm
Printhead parity
error<R>was not
recovered or print head
was not seated properly.
Replace the main control
board the carriage cable
and the printhead.
6
Printhead Type
Alarm
24 pin printhead is
connected in a 9 pin
printer.
Replace the printhead
with a 9 pin printhead.
7
Printhead
Connection Alarm
(1)
Overdrive signal is
active but no current is
detected.
Check the printhead
connection. Then
replace the main control
board the carriage cable
and the printhead.