HP LaserJet 3052 Service Manual - Page 98

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 ECU. 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 by using HP ToolboxFX). High voltage is disabled when the print-cartridge door is open. Figure 4-5 High-voltage power supply circuit on page 78 shows this process. 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 DC voltage generation circuit IC301 IC301 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 4-5 High-voltage power supply circuit 78 Chapter 4 Theory of operation ENWW