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Service Guide ML520/521
Chapter 4 Failure & Repair Analysis
RAP 11 Serial Interface Problem
START.
Are you using a cable with the proper number of pins?
No Change the interface cable.
Has the problem been resolved?
Yes End of procedure
No Go to A
Yes Is the ALARM LED blinking?
Yes Refer to Section 4.6 of the Service Handbook.
Has the problem been resolved?
Yes End of procedure
No Go to A
No Go to A
A
Check the serial interface parameters for the RS232C (in the Printer Menu): baud rate, word length, parity, protocol, busy signal and parity.
Has the problem been resolved?
Yes End of procedure
No Go to B
B
Check the voltages on the main control board.
Is 10 VAC being supplied to the main control board?
Yes Replace the RS232C board.
Has the problem been resolved?
Yes End of procedure.
No Replace the main control board.
Has the problem been resolved?
Yes End of procedure.
No Contact Technical Support.
No Replace the power supply unit.
Has the problem been resolved?
Yes End of procedure.
