Oki ML420 - Troubleshooting Flow Chart

42113901TH01 Rev.3 102 /
Oki Data CONFIDENTIAL
6.5 Troubleshooting flow chart
1 Power is not supplied.
Is the AC cable connected correctly?
Yes No
Connect the AC cable correctly.
Is fuse F1 on the transformer assy/or F1 on the Power Supply Board blown?
No Yes
Replace fuse (with same type and rating).
Remedied?
No Yes
End
Does DC + 50V out?
No Yes
Remove Printhead. (Turn power off, then on.)
Remedied?
No Yes
End
Replace carriage cable or ribbon feed mechanism.
Remedied?
No Yes
End
Replace Control Board.
Remove CN3 on Power Supply Board.
Measure for any short circuits between + 5V, + 50V, +12V, -8V, 0V in CN2 of Control
Board.
Any short circuit?
No Yes