viii CUSA EXcel Ultrasonic Surgical Aspirator System Service
Section 6. Principles of Operation
How the Handpiece Works 6-2
Electromechanical Operation 6-2
Fragmentation 6-3
Cooling 6-3
How the TissueSelect Feature Works 6-4
Inherent Tissue Selectivity 6-5
Increasing Tissue Selectivity 6-5
TissueSelect Reduces Reserve Power to the Tip 6-6
Benefits of TissueSelect 6-8
A Common Misunderstanding of the Amplitude Setting 6-9
Section 7. Circuit Theory
For Your Information 7-1
Display Board 7-2
General Description 7-2
Fundamentals of Operation 7-2
Detailed Circuit Description 7-3
Machine Control Board 7-4
Introduction 7-4
Irrigation Pump 7-4
Suction Pump 7-4
Cooling Pump 7-6
Suction Valve 7-6
Amplitude Control 7-6
Valve Controls 7-7
Power Control Input and Output Signals 7-7
Voltage Regulators 7-8
Interface Connectors 7-8
Ultrasonics Board–Ultrasonic Generator 7-8
Fundamentals of Operation 7-8
The Main Frequency Loop 7-9
Bandpass Filter (BPF) 7-9
AGC/Error Amplifier Circuit 7-10
Phase Compensator 7-11
Driver Stage 7-11
Feedback Signal 7-12
Bias Circuitry 7-12
Frequency Selection Circuitry 7-12
Ultrasonics Board–Other Circuits 7-13
Audible Alert and Operation Indicator 7-13
Valve Drivers 7-13