OKI MB491
Troubleshooting. LCD Display Trouble
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. |