Oki Data CONFIDENTIAL
43827101TH Rev.2
185 /
7.5.2.(1)
LCD Display Malfunction
(1-1)Nothing is displayed in LCD
F5 (fuse) of PU PCB
Connection between low-
voltage power supply unit and
PU PCB
Cord ASSY interconnecting
the low-voltage power supply
unit and the PU PCB
Connection between PU PCB
and operator panel PCB
FFC interconnecting the PU
PCB and the operator panel
PCB.
FFC interconnecting the PU
PCB and the CU PCB.
AC power supplied to the
printer
Voltage setting of low-voltage
power supply unit (100V
system/230V system)
5V power supplied to the PU
PCB
5V power supplied to the
operator panel PCB
5V power and 24V power
supplied to the PU PCB
Confirmation Tasks
Check to see if F5 is blown out.
Check to see if the cord from the low-voltage power supply is
connected properly to the POWER connector of the PU PCB.
Check for any incomplete connection or skew insertion.
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.
Check to see if the 7pin FFC is properly plugged into the OPE
connector of the PU PCB. Check to see if the 7pin FFC is
properly plugged into the CN connector of the operator panel
PCB. Check for any incomplete connection or skew insertion.
Check for wire breakage with a circuit-tester. Also, check
visually for peel-off of the covering.
Check to see if the 12pin FFC is properly plugged into the CUIF
connector of the PU PCB. Check similarly the CU PCB side
also.
Check the supply voltage of the AC power.
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.)
Check the 5V power at pin 7 of the POWER connector of the PU
PCB.
Check the 5V power at pin 4 of the CN connector of the operator
panel 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, one by one, and
locate the short-circuited part.
Action at NG
Replace F5 or PU
PCB.
Redo the insertion of
the cord properly.
Replace the cord with a
normal one.
Redo the insertion of
the cord properly.
Replace the FFC with a
normal one.
If the FFC is properly
plugged, replace the
low-voltage power
supply.
Supply AC power.
Set the low-voltage
power setting to the
proper values.
Replace the low-
voltage power supply.
Replace the F5 or PU
PCB.
Replace the short-
circuited part.
Confirmation Items
(1-1-1)Confirm fuse
(1-1-2)Confirm connection systems
(1-1-3)Confirm the power systems
(1-1-4)Confirm the power short