1)Lcd Display Malfunction; Lcd Display Malfunction; Nothing Is Displayed In Lcd - Oki C5500 Maintenance Manual

7.5.2.(1)

LCD Display Malfunction

(1-1)Nothing is displayed in LCD

Confirmation Items
(1-1-1)Confirm fuse
F5 (fuse) of PU PCB(PRX
PCB)
(1-1-2)Confirm connection systems
Connection between low-
voltage power supply unit and
PU PCB (PRX PCB)
Cord ASSY interconnecting
the low-voltage power supply
unit and the PU PCB (PRX
PCB)
Connection between PU
PCB(PRX PCB) and operator
panel PCB(PRP PCB)
FFC interconnecting the PU
PCB (PRX PCB) and the
operator panel PCB (PRP
PCB).
FFC interconnecting the PU
PCB (PRX PCB) and the CU
PCB.
(1-1-3)Confirm the power systems
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 (PRX PCB)
5V power supplied to the
operator panel PCB (PRP PCB)
(1-1-4)Confirm the power short
5V power and 24V power
supplied to the PU PCB (PRN
PCB)
43085101TH Rev.1
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(PRX 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(PRX 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.
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 (PRP 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 (PRX PCB).
Check the 5V power at pin 4 of the CN connector of the operator
panel PCB (PRP 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 (PRX PCB), one by
one, and locate the short-circuited part.
Oki Data CONFIDENTIAL
Action at NG
Replace F5 or PRX
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.
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 PRX
PCB.
Replace the short-
circuited part.
179 /