HP LaserJet 1010 Service Manual - Page 54

There are two overvoltage devices in this product: ● Fuse F101 provides overcurrent protection for the fusing system circuitry. ● Fuse F102 (110V products only) provides overcurrent protection to the printer DC power supply circuitry. You can check or replace the fuses by removing the left cover. If either of these fuses fail, replace the engine power assembly. High-voltage power distribution The high-voltage power supply applies an overlap of DC and AC voltage to the primary charging roller and to the developing roller. This circuit also applies a positive or negative DC voltage to the transfer roller according to the instructions from the engine control unit. This circuit also controls the image density by changing the primary AC voltage and the developing AC bias according to the print density setting (which is set using HP Toolbox). High voltage is disabled when the print cartridge door is open. Engine controller PCB Power supply PCB IC902 CPU PRPWM J902-10 J201-14 PRAC J902-9 J201-15 High-voltage power supply circuit Primary charging bias circuit IC301 IC301 IC301 DC voltage generation circuit Combined AC voltage generation circuit Primary PR1 J304 charging roller Photosensitive J303 drum DVAC J902-8 J201-16 TRPDC J902-6 J201-18 TRNDC J902-7 J201-17 TRCRNT J902-2 J201-22 Developing bias circuit DC voltage generation roller circuit IC301 Combined AC voltage generation circuit Transfer charging bias circuit Positive voltage generation circuit IC501 Negative voltage generation circuit Developing DEV J301 cylinder Transfer TRS J302 charging Figure 4-4. High-voltage power supply circuit 42 Chapter 4 Operational overview ENWW