Lcd Display Trouble; Lcd Displays Nothing - Oki MB461 Maintenance Manual

Oki Data CONFIDENTIAL

8.5.5.(1) LCD Display Trouble

(1-1) LCD displays nothing

Check item
(1-1-1) Checking fuse
Fuse on SU board (MHE) Check whether F1 or F5 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 (MHE) POWER connector on the SU
board (MHE) properly.
Cable assembly connecting
Check whether the cable
low-voltage power supply unit
connector is half-connected
to SU board (MHE)
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 is
board (MHE) and operation connected to the OPE connector
panel on the SU board (MHE) properly.
Make sure the 16-pin FFC is
connected to the CN1 connector
on the OPE board (OPM)
properly.
Check whether the cable
connector is half-connected or
tilted.
FFC connecting SU board Check for broken wires using a
(MHE) to OPE board (OPM) tester.
Check visually whether the
sheath peels.
44871001TH Rev.6
Checking Action in case of fail
Replace F1 or F5 or SU
board (MHE).
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 10-pin FFC
board (MHE) and CU/PU is connected to the GDIIF
board connector on the SU board (MHE)
properly.
Make sure the 10-pin FFC
is connected to the MFPIF
connector on the CU/PU board
(98M) properly.
Check whether the cable
connector is half-connected or
tilted.
FFC connecting SU board Check for broken wires using a
(MHE) to CU/PU board (98M) tester.
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.
5V power supplied to SU Check the 5V power at 3, 4pin of
board (MHE) the POWER connector on the SU
board (MHE).
3.3V power supplied to OPE Check the 3.3V power at 14pin of
board (OPM) the CN1 connector on the OPE
board (OPM).
(1-1-4) Checking for short circuit of power supply
5V and 24V power supplied to Check for a short circuit using
SU board (MHE) the POWER connector on the SU
board (MHE).
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 board (MHE) one by one to
locate the short circuit.
8. 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.
Replace the SU board
(MHE).
Replace the short-
circuited component.
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