(1) If the laser is certainly good, it may short-circuit the charging electrode and the grid;
(2) scan driver circuit logic errors;
(3) cartridge assembly discharge bad;
(4) the signal cables are not properly connected.
Check the location and maintenance methods:
(1) first replace the cartridge components, to see if the fault disappears, and if so, then the problem is the cartridge assembly, replace it.
(2) Then check the charging electrode wire and the grid for short or bad, and if so, should be replaced repaired or cleaned.
(3) If the above checks are intact, then the fault may occurred in the high-frequency laser scanner unit inside the drive circuit or logic circuit, it should check scan logic circuit is damaged, replace the scanning assembly.
(4) Sometimes, because of a printer with multiple computers linked to the signal line plug so check often can first check the signal cable is intact and plugged in, in order to avoid other unnecessary maintenance.
