Tektronix 7B85 Instruction Manual page 5

7885 Instruction
TABLE OF CONTENTS (cont)
Page
Section 3 THEORY OF OPERATION (cont)
ii
Trigger Generator ................ 3-6
External Source. . . . . . . . . . . . . . . 3-6
Internal and Line Source ........ 3-6
Trigger Source Selector and
Amplifier. . . . . . . . . . . . . . . . . . . . . 3-6
Peak-to-Peak Auto ............ 3-8
Slope Selector and Trigger
Generator. . . . . . . . . . . . . . . . . . . . 3-8
Gate Generator . . . . . . . . . . . . . . . 3-9
Logic .......................... 3-10
Sweep Modes . . . . . . . . . . . . . . . . 3-10
Hold Off Timing . . . . . . . . . . . . . . . 3-11
Lockout Buffer Amplifier . . . . . . . . 3-11
Hold Off Generator . . . . . . . . . . . . 3-11
Hold Off Output Amplifier . . . . . . . 3-11
Delay Pickoff Inhibit. ........... 3-12
Delay Mode Control. . . . . . . . . . . . 3-12
Auxiliary Y-Axis Generator . . . . . . 3-12
Sweep Generator. . . . . . . . . . . . . . . . 3-13
Timing Current Source. . . . . . . . . . 3-13
Ramp Generator . . . . . . . . . . . . . . 3-13
Output Preamplifier . . . . . . . . . . . . 3-13
Sweep Gate Generator . . . . . . . . . 3-16
Pickoff Amplifiers and Delay
Gate Generator. . . . . . . . . . . . . . . . . . 3-16
Delay Time Comparison
(SI\! B088750 & Up) ............ 3-16
Delay Time Comparison
(SN B088749
&
Below) ......... 3-16
~
Time Comparison
(SN B088750 & Up) ............ 3-16
~
Time Comparison
(SN B088749 & Below) ......... 3-18
Delay Bias and Second Delay
Pickoff Clamp ................. 3-18
Delay Comparison Voltage
Switch . . . . . . . . . . . . . . . . . . . . . . 3-18
Delay Gate Generator . . . . . . . . . . 3-18
~Symbol Enable ............... 3-19
Digital Voltmeter ................. 3-19
Delay Comparison Voltage to Ramp
Converter (SN B088750 & Up) ... 3-20
Delay Comparison Voltage to Ramp
Converter (SN B088749 & Below) 3-21
Page
Comparator (SN B088750 & Up) . 3-21
Comparator (SN B088749 &
Below) ...................... 3-21
Ramp Control ................ 3-21
Divide by 4 Counter ............ 3-21
Timer ....................... 3-21
Reference Current Source
(SN B088750 & Up) ............ 3-22
Reference Current Source
(SN B088749 & Below) ......... 3-22
Reference Current Inverter
(SN B088750 & Up) ............ 3-22
Reference Current Inverter
(SN B088749 & Below) ......... 3-22
Reference Current Switch. . . . . . . 3-22
Counter and Encoder
(SN B088750 & Up) ............ 3-22
Counter and Encoder
(SN B088749 & Below) ......... 3-22
Counter Transfer Control. ....... 3-23
Zero Count Correction .......... 3-23
Time/Division and Readout
Switching . . . . . . . . . . . . . . . . . . . . . . 3-23
Basic Readout System . . . . . . . . . 3-23
Time/Division and Readout . . . . . . 3-23
Delay Time Readout ........... 3-23
Interface Connectors and Power
Supply. . . . . . . . . . . . . . . . . . . . . . . . . 3-24
Section 4 MAINTENANCE
Preventive Maintenance ............. 4-1
Cleaning . . . . . . . . . . . . . . . . . . . . . . . 4-1
Exterior . . . . . . . . . . . . . . . . . . . . . 4-1
Interior ...................... 4-1
Switch Contacts . . . . . . . . . . . . . . 4-1
Visual Inspection ................ 4-1
Lubrication . . . . . . . . . . . . . . . . . . . . . 4-2
Cam Switch Lubrication ......... 4-2
Semiconductor Checks. . . . . . . . . . . . 4-2
Adjustment After Repair ........... 4-2
Troubleshooting ................. 4-3
REV AUG 1981