The RAM on the DC controller PCB keeps count of copies being made; when it hasdetected the hopper toner level detection signal ( =1) for 1 sec or more, it will assumethe presence of toner, thereby cleaning the counter and turning off the Add Tonermessage on the control panel.Reference:The inside of both the developing assembly and the hopper assembly is eachequipped with a piezoelectric oscillator.In the absence of toner, the oscillator oscillates at several kHz, and the output ofthe sensor goes ‘0’. In the presence of toner, on the other hand, the weight of thetoner stops the oscillation, and the output of the sensor goes ‘1’.Figure 4-203If the developing assembly is not set inside the copier, do not install the developingassembly locking assembly. Otherwise, the toner collecting in the path from thehopper to the developing assembly can pour out because of the vibrations causedby inspection/repair work.AMPPiezoelectric oscillatorIntegrationcircuitOutputTEPTEPCOPYRIGHT © 1997 CANON INC. CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)CHAPTER 4 IMAGE FORMATION SYSTEM4-31Caution:Download service manual and resetter printer at http://printer1.blogspot.com
