HP 8550 Service Manual - Page 511

E351 Cause Power supply ECO PCB/ AP-IP PCB Step 1 2 Checks Yes/No Action Are the PCBs and connectors NO connected securely? (If the power supply is cut abnormally, the copier can indicate "E351" when it warms up. If this occurs, turn the copier off and then on to reset.) Make the connections secure, and turn the copier off and then on. Are the CO PCB and AP-IP PCB NO connected securely? YES Connect the PCBs securely. Replace the parts in the order indicated: ECO PCB AP-IP PCB E353 E353 is indicated in response to a mismatch of the serial number of the reader controller PCB and that of the EEPROM while the reader controller PCB is being replaced. See "Removing the electrical unit pullout" on page 367. E355 E355 is indicated in response to a mismatch of the serial numbers of the copy module, the reader controller PCB, and the EEPROM while the reader controller PCB is being replaced (as when the wrong serial number is entered). If this code appears, enter the correct serial number of the copy module using OPTION > USER > SERIAL in service mode. E401 The error shown on the touch-screen display is in the ADF. See "ADF troubleshooting" on page 528. This error indicates that either the pick-up motor (M1) fails to rotate or the pick-up roller sensor (S5) is faulty. In normal operation, a flag is attached to the spindle of the pick-up motor (M1), and the rotation of the motor is checked in reference to the flag blocking the pick-up roller sensor (S5). The E401 error is indicated when the sensor does not turn on and off two times or more within one second. EN Copy module troubleshooting 509