Oki Data CONFIDENTIAL
44158801TH Rev.2
225 /
8.5.2.(1)
LCD Display Malfunction
(1-1) Nothing is displayed in LCD
Confirmation Items
Confirmation Tasks
Action at NG
(1-1-1) Confirm fuse
F5 (fuse) of PU PCB (PRF
PCB)
Check to see if F5 is blown out.
Replace F5 or PRF
PCB.
(1-1-2) Confirm connection systems
Connection between low-
voltage power supply unit
and PU PCB (PRF PCB)
Check to see if the cord from the low-voltage power
supply is connected properly to the POWER connector
of the PU PCB (PRF PCB). Check for any incomplete
connection or skew insertion.
Redo the insertion
of the cord properly.
Cord ASSY interconnecting
the low-voltage power
supply unit and the PU
PCB (PRF PCB)
Check to see if the cord has any wire breakage.
Check to see if the cord has any peel-off of the covering.
Check for any fault in the cord ASSY, such as dislocated
wire, etc.
Replace the cord
with a normal one.
Connection between PU
PCB (PRF PCB) and
operator panel PCB (PRP
PCB)
Check to see if the 7pin FFC is properly plugged into the
OPE connector of the PU PCB (PRF PCB). Check to see
if the 7pin FFC is properly plugged into the CN connector
of the operator panel PCB (PRP PCB). Check for any
incomplete connection or skew insertion.
Redo the insertion
of the cord properly.
FFC interconnecting the
PU PCB (PRF PCB) and
the operator panel PCB
(PRP PCB).
Check for wire breakage with a circuit-tester. Also, check
visually for peel-off of the covering.
Replace the FFC
with a normal one.
FFC interconnecting the
PU PCB (PRF PCB) and
the CU PCB.
Check to see if the 12pin FFC is properly plugged into
the CUIF connector of the PU PCB (PRF PCB). Check
similarly the CU PCB side also.
Replace the low-
voltage power
supply.
(1-1-3) Confirm the power systems
AC power supplied to the
printer
Check the supply voltage of the AC power.
Supply AC power.
Voltage setting of low-
voltage power supply
unit (100V system/230V
system)
Measure the supplied AC voltage. Check the power
supply settings of the printer in use. (Check the short-
circuit plug designed for switching of low-voltage power
setting. Short-circuit plug provided/not provided = 100V
system/230V system.)
Set the low-voltage
power setting to the
proper values.
5V power supplied to the
PU PCB (PRF PCB)
Check the 5V power at pin 7 of the POWER connector of
the PU PCB (PRF PCB).
Replace the low-
voltage power
supply.
5V power supplied to the
operator panel PCB (PRP
PCB)
Check the 5V power at pin 4 of the CN connector of the
operator panel PCB (PRP PCB).
Replace the F5 or
PRF PCB.
(1-1-4) Confirm the power short
5V power and 24V power
supplied to the PU PCB
(PRF PCB)
Check for short-circuiting through the POWER connector
of the PU PCB.
4, 5, 6 pin: 24V
7 pin: 5V
8 pin: 0VL
1, 2, 3 pin: 0VP
If there is any short-circuiting, locate it by isolation.
Unplug the cords connected to the PU PCB (PRF PCB),
one by one, and locate the short-circuited part.
Replace the short-
circuited part.