Oki Data Confidential; Lcd Display Trouble; Lcd Displays Nothing - Oki MC561 Maintenance Manual

Oki Data CONFIDENTIAL

7.5.4.(1) LCD Display Trouble

(1-1) LCD displays nothing

Check item
(1-1-1) Checking fuse
Fuse on SU PCB Check whether F2 has blown.
(1-1-2) Checking connections
Connection between low- Make sure the low-voltage power
voltage power supply unit and supply unit is connected to the
SU PCB POWER connector on the SU
PCB properly.
Cable assembly connecting
Check whether the cable
low-voltage power supply unit
connector is half-connected
to SU PCB
or tilted, or whether wires are
broken.
Check whether there is any
fault in the cable assembly, e.g.,
missing wires.
Connection between SU PCB Make sure the 16-pin FFC is
and operation panel connected to the OPE connector
on the SU PCB properly.
Make sure the 16-pin FFC is
connected to the CN1 connector
on the operation panel PCB
properly.
Check whether the cable
connector is half-connected or
tilted.
FFC connecting SU PCB to Check for broken wires using a
operation panel PCB tester.
Check visually whether the
sheath peels.
44473001TH Rev.1
Checking Action in case of fail
Replace F2 or SU PCB.
Connect the cable
properly.
Replace the cable with
a good cable.
Connect the cable
properly.
Replace the cable with
a good cable.
Check item
(1-1-3) Checking power supplies
AC power supplied to the Check the supplied voltage from
printer the AC power source.
5V power supplied to SU PCB Check the 5V power at 3, 4pin of
the POWER connector on the SU
PCB.
3.3V power supplied to Check the 3.3V power at 14pin
operation panel PCB of the CN1 connector on the
operation panel PCB.
(1-1-4) Checking for short circuit of power supply
5V and 24V power supplied to Check for a short circuit using
SU PCB the POWER connector on the SU
PCB.
7, 8pin: 24V
3, 4pin: 5V
5, 6pin: 0VL
9, 10pin: 0VP
If there is a short circuit, locate it.
Disconnect the cables from the
SU PCB one by one to locate the
short circuit.
(1-1-5) Checking LSI operation
I/F signal from SU PCB to Check whether signals are output
operation panel PCB to the OPE connector on the SU
PCB.
9pin: Transmission data (sent
from the SU PCB)
11pin: Clock
13pin: Enabling
15pin: Reset
Signals should be always output
under normal conditions.
7. TROUBLESHOOTING PROCEDURES
Checking Action in case of fail
Supply AC power.
Replace the low-voltage
power supply.
Replace the SU PCB.
Replace the short-
circuited component.
Replace the SU PCB.
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