Lcd Display Trouble; Lcd Displays Nothing; Checking Connections; Checking For Short Circuit Of Power Supply - Oki MB472w Maintenance Manual

Oki Data CONFIDENTIAL

2.5.5.(1) LCD Display Trouble

(1-1) LCD displays nothing

Check item
(1-1-1) Checking fuse
Fuse on SU board (MSU) Check whether F6 or F8 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 board (MSU) POWERCN connector on the SU
board (MSU) properly.
Cable assembly connecting
Check whether the cable
low-voltage power supply unit
connector is half-connected
to SU board (MSU)
or tilted, or whether wires are
broken.
Check whether there is any
fault in the cable assembly, e.g.,
missing wires.
Connection between SU Make sure the 16-pin FFC
board (MSU) and operation is connected to the OPE2
panel connector on the SU board (MSU)
properly.
Make sure the 16-pin FFC is
connected to the CN1 connector
on the OPE board (OPM-2)
properly.
Check whether the cable
connector is half-connected or
tilted.
FFC connecting SU board Check for broken wires using a
(MSU) to OPE board (OPM-2) tester.
Check visually whether the
sheath peels.
45762101TH Rev.1
Checking Action in case of fail
Replace F6 or F8 or SU
board (MSU).
Connect the cable
properly.
Replace the cable with
a good cable.
Connect the cable
properly.
Replace the cable with
a good cable.
Check item
(1-1-2) Checking connections
Connection between SU Make sure the 16-pin FFC
board (MSU) and CU/PU is connected to the OPE1
board connector on the SU board (MSU)
properly.
Make sure the 16-pin FFC
is connected to the OPE
connector on the CU/PU board
(MRM) properly.
Check whether the cable
connector is half-connected or
tilted.
FFC connecting SU board Check for broken wires using a
(MSU) to CU/PU board tester.
(MRM) Check visually whether the
sheath peels.
(1-1-3) Checking power supplies
AC power supplied to the Check the supplied voltage from
printer the AC power source.
5VS and 24V power supplied Check the 5VS power at 1 pin
to SU board (MSU) and 24V power at 3, 4 pin of the
POWERCN connector on the SU
board (MSU).
5VOPE and 3.3VSF power Check the 5VOPE power at 16pin
supplied to OPE board (OPM- and 3.3VSF power at 14pin of the
2) CN1 connector on the OPE board
(OPM-2).

(1-1-4) Checking for short circuit of power supply

5V and 24V power supplied to Check for a short circuit using
SU board (MSU) the POWER connector on the SU
board (MSU).
3, 4pin: 24V
1pin: +5VS
2, 5, 6pin: 0V
If there is a short circuit, locate it.
Disconnect the cables from the
SU board (MSU) one by one to
locate the short circuit.
2. TROUBLESHOOTING PROCEDURES
Checking Action in case of fail
Connect the cable
properly.
Replace the cable with
a good cable
Supply AC power.
Replace the low voltage
power supply or CU
Board (MRM).
Replace the SU board
(MSU).
Replace the short-
circuited component.
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