Brother International HL-2600CN Service Manual - Page 332

I-3 Jitter Phenomenon Uneven optical density appears periodically in the horizontal direction on the printed image as shown in print sample (3) of Fig.8-2. Main Causes Failure of main motor. 1) Irregular rotation of the drive motor. 2) Failure of the gears. 3) Variation of OPC belt running speed due to above reasons. 4) Too much rotational load of the OPC belt. Countermeasures 1) Replace the main motor with a new one. (See Section 4.2.8 of Chapter VII.) 2) Replace the OPC belt cartridge with a new one. (See Section 2.1 of Chapter VI.) I-4 Ribbing Phenomenon Light print occurs on the right or left hand side of the image as shown in print sample (4) of Fig.8-2. Main Causes 1) Slight tilt on the surface of printer installation table. (Tilt should be less than 1 .) 2) Toner amount in the toner cartridge is insufficient. (The amount in a full cartridge should be 175g for Y, M, & C and 275g for K.) 3) Toner cartridge is not laid as level, and as the result, toner concentrates to one side. 1 Fig.8-3 Countermeasures 1) Confirm that the printer installation table is flat and level. 2) Replace the toner cartridge with a new one. 3) Shake the toner cartridge horizontally for several times to remedy the concentration.