Lcd Display Error; Lcd Does Not Display Anything - Oki C710 Maintenance Manual

Oki Data CONFIDENTIAL

7.5.2. (1) LCD display error

Memo For the numbers from 1 through 26 after name of the respective connectors,
refer to section 7.5.2 (19) "Wiring diagram".

(1-1) LCD does not display anything.

Check item
(1-1-1) Check the fuse.
F2 (fuse) of the PU Check if F2 has blown out or not.
board
(1-1-2) Check the system connection
Connection between Check if the cable from the low voltage power
the low voltage supply to the POWER connector
power supply unit board is normally connected or not.
and the PU or CU
Check if the connector is connected only in the
board.
half-way or not, and check if the connector is
inserted in slanted angle or not.
Cable assembly Check if the cable is half-open circuit.
connecting the Check if sheath of the cable has not peeled off
low voltage power or not.
supply unit and the Check if the cable assembly is defective such as
PU board. internal wires are disconnected or not.
Connection between Check if the 10-conductor FFC is connected to
the PU board and the OPE connector
Operator Panel or not.
Check if the 10-conductor FFC is connected to
the OPE connector
or not.
Check if the connector is connected in the half-
way only or not, and check if the connector is
inserted in a slanted angle or not.
FFC connecting Check if the cable has open circuit or not with
the PU board and VOM. Check if sheath of the cable has not
the Operator Panel peeled off or not by visual inspection.
board
FFC connecting the Check if the 16-conductor FFC is connected to
PU board and the the CU IF connector
CU board or not. Check the CU board side in the same
way.
43856301TH Rev.3
Action to be taken
Check work
at NG
Replace F2 or
the PU board.
Re-connect the
of the PU cable normally.
Replace the
cable with the
normal cable.
Note!
Re-connect the
of the PU board normally cable normally.
of the PU board normally
Replace the
FFC with the
normal FFC.
Replace the low
of the PU board normally voltage power
supply.
Note!
Check item
(1-1-3) Check the peripherals of the power supplies
Primary AC power Check the supplied voltage of the AC power
source that is source.
connected to the
printer.
Voltage setting of Measure the AC voltage supplied.
the lower voltage Check the power voltage setting of the
power supply unit equipment in use.
(100V system/230V (Check the shorting plug that is used for
system) selection of the voltage power supplies.)
Shorting plug is Used/Not used = 100V system/
230V system.
5V power that is Check for the 5V power supply at pin-7 of the
supplied to the PU POWER connector
board.
3.3V power that Check for the 3.3V power supply at pin-10 of the
is supplied to the CN connector
Operator Panel.
(1-1-4) Check that power supply circuit has no short-circuit.
5V power and 24V Check that power supply circuit has no short-
power that are circuit at the POWER connector no. 10 of the
supplied to the PU PU board. The follow voltage must appear
board. respectively.
pins-4, 5 and 6: 24V
pin-7: 5V
pin-8: 0VL
pins-1, 2 and 3: 0VP
If any voltage does not appear and short-circuit
is detected, locate the source of the short-circuit
as follows:
Disconnect the cables that are connected to the
PU board one cable after another until location
of the short-circuit is found out.
Note! If the PU board, the CU board and the
low voltage power unit are connected one
another differently from the picture given
below, it is regarded as an abnormal, and
the output from the low voltage power unit
stops.
When the output from the low voltage power
unit stops, turn off the power switch, wait
about one minute, and then turn on the
power switch, otherwise, the alarm condition
of the stoppage of the power output is not
cleared.
7. Troubleshooting and repair procedure
Action to be taken
Check work
at NG
Supply the AC
power.
Set the low
voltage power
supply setting.
Replace the low
of the PU board.
voltage power
supply.
Replace F2 or
of the Operator Panel board.
the PU board.
Replace the part
causing short-
circuit.
PU board CU board
low voltage power unit
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