If the measurement dose not fall within the tolerance after eight tires, ‘1’ is indicat-ed to ‘LLMT’ (upper limit flag of lamp activation voltage) in service mode (*1*; dis-play mode).c. Controlling the Developing BiasThe light area potential (VL2) for the developing bias is measured in terms of the sur-face potential of the drum occurring when the scanning lamp is turned on based on thelast intensity adjustment signal generated during VL1 control.The DC controller PCB uses the measurement to control the developing bias DClevel control signal (DEVDC) to control the DC bias applied by the high-voltage trans-former on the developing cylinder.3. Potential Measurement CircuitFigure 4-103 is a cross sectional diagram of the potential sensor, and Figure 4-104is a block diagram of the potential measurement circuit.The drive signal from the sensor drive circuit drives the chopper so that the electrodeof the sensor assembly can detect the drum surface potential.The measurement signal of the drum surface signal is amplified by the pre-amplifiercircuit, and is sent to the drum surface potential detection circuit.The drum surface potential detection circuit converts the AC signal to an AC signal,and sends it to the level shift circuit through the 1/300 transformer circuit.The output signal (analog) of the level shift circuit is sent to the microprocessor onthe DC controller PCB.a. Making Checksq LED1 ActivationLED1 is normally on when the main motor rotates.If it does not turn on, you may suspect a fault in the potential measurement unit.Reference:When LED1 is on normally, the potential sensor is operating normally.The sensor and the potential measurement PCB are adjusted to a high precision asa pair, and cannot be adjusted in the field. They are treated as a single entity ser-vice part.CHAPTER 4 IMAGE FORMATION SYSTEM4-4 COPYRIGHT © 1997 CANON INC. CANON NP6560/NP6360/NP6260 REV. 0 NOV. 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)Caution:Caution:
