Dell 2135cn Service Manual page 799

Chapter 6 Principle of Operation CONTENTS
1. Telephone System......................................................................................................6 - 1
1.1 Converting and Sending Voice in the Form of Electrical Signals..................................................... 6 - 1
1.2 Analog and Digital Signals ............................................................................................................... 6 - 3
2. Telephone Call Connection Mechanism.....................................................................6 - 6
2.1 Analog Telephone Network.............................................................................................................. 6 - 6
2.2 Telephone Call Connection Mechanism .......................................................................................... 6 - 7
3. Terminology..............................................................................................................6 - 10
4. FAX System (Overview) ...........................................................................................6 - 11
5. Unit Mechanisms ......................................................................................................6 - 13
6. FAX Standards (ITU-T Recommendations)..............................................................6 - 16
7. Fault Isolation Procedure for FAX ............................................................................6 - 17
7.1 Fault Occurs................................................................................................................................... 6 - 17
7.2 Send Fault...................................................................................................................................... 6 - 17
7.3 Receive Fault ................................................................................................................................. 6 - 18
8. Other Problems ........................................................................................................6 - 19
9. Document Scanning .................................................................................................6 - 20
9.1 Document Scanning at Platen (IIT)................................................................................................ 6 - 21
9.2 Document Scanning at ADF .......................................................................................................... 6 - 22
9.2.1 Setting a Document ............................................................................................................... 6 - 23
9.2.2 Preparation for Feed .............................................................................................................. 6 - 23
9.2.3 Prefeed .................................................................................................................................. 6 - 23
9.2.4 Scan Control .......................................................................................................................... 6 - 23
9.2.5 Simplex Document................................................................................................................. 6 - 24
10. Image Data Flow ....................................................................................................6 - 26
11. Drive Torque Transfer Scheme ..............................................................................6 - 27
11.1 ADF Motor.................................................................................................................................... 6 - 27
11.2 Gear Layout ................................................................................................................................. 6 - 28
12. Names and Functions of Components ...................................................................6 - 29
12.1 IIT................................................................................................................................................. 6 - 29
12.2 ADF.............................................................................................................................................. 6 - 31
13. Control ....................................................................................................................6 - 35
13.1 Document Scanning Steps .......................................................................................................... 6 - 35
13.1.1 AOC (Auto Offset Control) ................................................................................................... 6 - 35
13.1.2 AGC (Auto Gain Control): White Level Variation Adjustment .............................................. 6 - 35
13.1.3 Shading Compensation........................................................................................................ 6 - 35
13.2 CCD Image Sensor Overview...................................................................................................... 6 - 36
13.3 System Configuration................................................................................................................... 6 - 37
Version 2 2008.03.31
Chapter 6 Principle of Operation