OKI MPS4700

LCD displays nothing

Check item	Checking	Action in case of fail
Checking fuse
Fuse on SU board (MSU)	Check whether F5 or F7 has blown.	Replace F5 or F7 or SU board (MSU).
Checking connections
Connection between lowvoltage power supply unit and SU board (MSU)	Make sure the low-voltage power supply unit is connected to the POWERCN connector on the SU board (MSU) properly. Check whether the cable connector is half-connected or tilted, or whether wires are broken. Check whether there is any fault in the cable assembly, e.g., missing wires.	Connect the cable properly.
Cable assembly connecting low-voltage power supply unit to SU board (MSU)		Replace the cable with a good cable.
Connection between SU board (MSU) and operation panel	Make sure the 22-pin FFC is connected to the 7 INCHIF connector on the SU board (MSU) properly. Make sure the 22-pin FFC is connected to the SUIF connector on the touch panel board (TP1) properly. Check whether the cable connector is half-connected or tilted.	Connect the cable properly.
FFC connecting SU board (MSU) to OPE board (TP1)	Check for broken wires using a tester. Check visually whether the sheath peels.	Replace the cable with a good cable.
Connection between SU board (MSU) and CU/PU board	Make sure the 50-pin FFC is connected to the MFPIF connector on the SU board (MSU) properly. Make sure the 50-pin FFC is connected to the MFPIF connector on the CU/PU board (MRM) properly. Check whether the cable connector is half-connected or tilted.	Connect the cable properly.
FFC connecting SU board (MSU) to CU/PU board (MRM)	Check for broken wires using a tester. Check visually whether the sheath peels.	Replace the cable with a good cable
Checking power supplies
AC power supplied to the printer	Check the supplied voltage from the AC power source.	Supply AC power.
5VS and 24V power supplied to SU board (MSU)	Check the 5VS power at 1 pin and 24V power at 3, 4 pin of the POWERCN connector on the SU board (MSU).	Replace the low voltage power supply or CU/PU board (MRM)
5V and 5VS power supplied to OPE board (TP1)	Check the power at pin of the CN1 connector on the OPE board (TP1).	Replace the SU board (MSU).
Checking for short circuit of power supply
5V and 24V power supplied to SU board (MSU)	Check for a short circuit using 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.	Replace the shortcircuited component.

Display of OKI logo

Check item	Checking	Action in case of fail
Operation panel display does not change.
Operation panel display	OKI logo stays on.	Replace the OPE board (TP1).

Error message display

Check item	Checking	Action in case of fail
Error message
Error message display	Check the detail of the error on the error message list.	Follow the instructions.