HP error 51 code is termed as the beam detected an error.
The beam detected error refers to the laser beam reflected from a spinning hexagonal mirror and scanner across the drum. At the scanning end, the laser is turned on, and the reflected beam is radiated onto the fixed mirror and then darted through an optical fiber onto the DC control board. The electronics on this board detect the pulse from the photodiode and then provide a timing signal for the data sent to the laser. Hence, the fault can be the laser, the scanner motor, assorted optical bits, or the dc controller board
On older models, the error indicates that the label on the bottom of the cartridge will open the missing or broken laser shutter. In comparison, on newer models, the problem may be the laser scanner unit.
Steps to fix the Error 51 (The loss of beam detected error) is as follows:
Let us first proceed with the manual guidelines:
- Start with running the laser/scanner motor component test.
- If you are unable to hear the rotation of the motor, kindly check the DC controller PCA.
- Keep a note that the controllers should be seated in DC controller PCA
- Even after the above steps, if the printer shows an error, unfortunately, the laser/scanner assembly needs to be replaced.
To remove the laser scanner unit, kindly follow the below steps:
- The DIMM cover ell open by sliding the DIMM cover towards the rear of the printer.
- Remove the cover, and then carefully lift it.
- Remove one screw to loosen the formatting cover, and then carefully slide it toward the rear of the printer.
- Slowly open the rear door of the module.
- Now relax the upward hinge arm.
- Remove the two screws.
- Open the lower back door and carefully release the tab.
- Rotate the rear door assembly and carefully remove it.
- Remove one screw on the left cover to release the tab.
- Now carefully twist the back of the lid.
- Remove the first three screws, and then lift the top from the product to remove it completely.
- Press the release button on the cartridge door to open it.
- Disconnect the connector and carefully remove one screw.
- Carefully slide the control panel forward to release the control panel.
- Now gently lift the air duct by releasing the upper tab.
- Carefully remove the antistatic sponge, and then disconnect the connector and FFC (Flexible Flat Cable)
- In the end, the laser/scanner lobe removed from the printer by unscrewing four screws.
The above solution is the most effective and widely used method to correct Error 51 on HP printers. I hope this helps!