HP — HP Color LaserJet Enterprise M750 Service Manual (EN)

Table of contents 1 Theory of operation ....................................................................................................................................... 1 Basic operation ...................................................................................................................................................... 2 Major product systems ........................................................................................................................ 2 Product block diagram ........................................................................................................................

2 Sequence of operation ........................................................................................................................ 3 Normal sequence of operation ......................................................................................... 3 Formatter-control system ..................................................................................................................................... 5 Sleep mode ..........................................................................................................................................

5 Input/output ........................................................................................................................................ 5 CPU ....................................................................................................................................................... 6 Memory ................................................................................................................................................ 6 Firmware ...........................................................................................................................

6 Nonvolatile memory ......................................................................................................... 6 PJL overview ........................................................................................................................................ 6 PML ...................................................................................................................................................... 6 Control panel .......................................................................................................................................

6 Engine-control system .......................................................................................................................................... 7 DC controller ........................................................................................................................................ 8 Motors ............................................................................................................................. 11 Fans .................................................................................................................................

13 Fuser-control circuit ....................................................................................................... 14 Fuser temperature control ........................................................................... 15 Fuser protective function ............................................................................. 16 Fuser failure detection ................................................................................. 17 Low-voltage power supply ............................................................................................. 18 Overcurrent/overvoltage protection ...........................................................

20 Laser scanner system ....................................................................................................................... 23 High-voltage power supply ............................................................................................ 21 Laser failure detection .................................................................................................... 23 Image-formation system .................................................................................................................................... 25 Electrophotographic process ............................................................................................................

25 Image formation process .................................................................................................................. 27 ENWW v