Power-on defectsTable 16. Power malfunctions
Item

 

Solution

 

 

 

ADF unit or scan unit does not function.

● Print a print-engine test (see the HP LaserJet 4100

 

 

 

series printer service manual for more information).

 

 

 

This helps to isolate the power malfunction to the print

 

 

 

unit or the scan unit.

 

 

 

● Verify that the power connector from the print unit to

 

 

 

the scan unit is correctly plugged in at both ends. See

 

 

 

“Back view” on page 21.

 

 

 

● Verify that the flatbed intake fan is functioning (the unit

 

 

 

is receiving power). If the fan is not functioning, verify

 

 

 

that the connectors at J1203 (scanner controller PCB)

 

 

 

and J1201 (power supply) are correctly connected

 

 

 

and fully seated.

 

 

 

 

● Check for frayed, pinched, or damaged wires.

 

 

 

● Verify that the flatbed power supply is functioning.

 

 

Printer is functioning (power on, fans running,

● Verify that the control-panel cable connector location

and so forth) but the control-panel display is

J1210 on the scanner controller PCB is correctly

blank or displays garbled text.

connected and fully seated.

 

 

 

● Verify that the control-panel wire harness is correctly

 

 

 

connected to the control-panel door (located behind

 

 

 

the control-panel grounding strip). See “Control-panel

 

 

 

door” on page 79.

 

 

 

 

● Verify that the power supply in the flatbed unit is

 

 

 

functioning.

 

 

 

 

● Check for frayed, pinched, or damaged wires.

 

 

 

● Replace the control panel.

 

 

 

 

 

 

 

 

Hint

The control panel gets its power from the power supply in the scan unit, not

 

 

the power supply in the print unit.

 

 

 

 

 

 

 

 

 

 

No ac power.

 

 

 

 

 

Defective power-supply unit.

● Verify that the power-supply fuse is not blown (power-

 

 

 

supply PCB location F101).

 

 

 

● Verify that all power-supply connectors are fully

 

 

 

seated.

 

 

 

 

● Replace the power supply. See “Scan-unit power

 

 

 

supply” on page 101.

 

 

 

 

No dc power.

 

 

 

 

 

No ac power is supplied.

● Check for ac power.

 

 

The overcurrent/overvoltage detection circuit is

● Turn off the MFP and then turn it back on. If the

activated.

 

problem persists, find the cause of the overcurrent/

 

 

 

overvoltage on the load side of the power-supply

 

 

 

circuits. See “Power supply” on page 63.

 

 

 

 

 

 

 

 

Note

Leave the MFP off for two minutes.

 

 

 

 

 

Defective wiring, dc loads, or scanner

● Turn off the power switch. Check the wiring ahead of

controller PCB.

 

the scanner controller PCB and check the dc loads. If

 

 

 

you discover the problem, replace the wiring and dc

 

 

 

loads. If no problem exists on the wiring or dc loads,

 

 

 

replace the scanner controller PCB. See “Power

 

 

 

supply” on page 63.

 

 

 

 

 

116 Troubleshooting

C9148-90909