Oki ML420 Maintenance Manual page 116

3. TROUBLESHOOTING FLOWCHART
3.1 Before Repairing a Fault
Before servicing the printer, ask the customer in what situation the trouble occurred and record
the response.
Before starting troubleshooting, operate the printer in the same situation as that at the time of
trouble occurrence to see if the same trouble occurs again. If not, perform the printers self test
and thoroughly test the printers functionality. If the trouble is reproducible proceed to the
troubleshooting section.
3.2 Troubleshooting
(1) The data is not received using a serial interface.
(2) Using a serial interface, the print data is omitted or the print operation is not performed.
1
The data is not received using a serial interface.
(A protocol is set to READY/BUSY state, and BUSY LINE is in SSD + state.)
The RxD of RSDV1 as specified in Figure B-1?
Yes Replace the Main Control PCB.
2
In receiving by serial interface, printing data is omitted or printing operation is not performed.
Are RxD and SSD of RSDV1, RSDV2 as specified in Figure B-1?
Yes Replace the Main Control PCB.
42114131TH Rev.1
RxD
ST bit
SSD
No Replace the RS232C optional board.
No Replace the RS232C optional board.
Figure B-1
Oki Data CONFIDENTIAL
5V
0V
SP bit
5V
0V
116 /