Equipment information

Fairchild Instrumentation 74-13A Oscilloscope
Manufacturer:
Model:
74-13A
Date:
1965
Category:
Group:
Description:
Calibrated Delaying Sweep

Information

PLEASE NOTE IMPORTANT INITIAL ADJUSTMENTS MUST BE MADE BEFORE OPERATING THIS Plug-In MODULE. See Paragraph 21 entitled "First Time Operation” in Section 2 for instructions. The Type 74-13A Dual Time Base Calibrated Delaying Sweep is designed for use with the Fairchild Type 765/765H Series of Transistorized Oscilloscopes. To simplify circuit description, the following abbreviations are employed to describe the dual time base delaying sweeps. Abbreviation Description NDT The NDT sweep refers to Normal Sweep operation and Delaying Triggered operation (i.e., the delayed sweep starts immediately after the delay pick-off trigger is generated). DA The DA sweep refers to Delayed Armed operation (i.e., the delaying sweep (NDT) generates a delay pick-off trigger which arms the DA sweep). An input trigger signal is then required to fire the DA sweep. 1-2. TECHNICAL SUMMARY The performance specification of this Plug-In module is given in the technical summary which follows. TIME BASE SYSTEM Calibrated Sweep Range (NDT & DA) Calibrated linear sweep rates from 0.1 /¿sec/div to 2 sec/div in 23 steps of 1, 2, and 5 sequence Uncalibrated Sweep Range The Sweep Vernier control provides a continuous uncaiibrated range of sweep rates between ranges and extends the 2 sec/div range to 5 sec/div (50 seconds full scale). The UNCAL lamp serves as an indicator of uncaiibrated or vernier operation Sweep Accuracy ±3% measured over the centered 8 div portion of the CRT screen Sweep Range Indicator Push-pull clutch knob permits simultaneous or independent control of the NDT and DA sweep rates Sweep Expander A calibrated XI0 sweep expander in the X output Amplifier will expand the sweep about screen center; extends fastest sweep rate to 10 nano-seconds/div. Expander accuracy is ±5% for speeds faster than 200 nanoseconds/div and ±3% for slower sweeps. Neglect the first 50 nanoseconds Sweep Calibration A front-panel screwdriver SWP CAL control Is provided to permit normalization of the Plug-In unit to the Main Frame and standardizing the sweeps to an external time standard Gate Out (NDT & DA) Two front-panel banana ¡acks each provide a positive-going pulse of 2.5 volts nominal. Output impedance is 500 ohms. For optimum performance, load impedance should be greater than 100K ohms and shunted by less than 15 pf. Gate is referenced directly to ground and is time-coincident with the sweep Saw Panel banana jack provides a positive saw output of approximately 25 volts and is coincident with the NDT Sweep. Output impedance is nominally 1 OK ohms, and load impedance should be greater than 100K ohms shunted by less than 15 pf Other Controls Internal controls optimize settings of automatic strobe intensity and strobe transition. This normalizes the Plug-In to the CRT of the Main Frame and avoids having to reset the intensity control when observing strobed display modes SWEEP MODES Normal Sweep Operation Conventional sweep display. Internally or externally applied trigger signals drive the NDT time base circuit Delayed-Triggered Strobe Delaying sweep display showing the delayed sweep as a brightened sector. The delayed sweep starts immediately after the delay pick-off trigger is generated Delayed-Armed Strobe Delaying sweep display showing the delayed sweep as a brightened sector, but delayed sweep (brightened sector) is armed by the delayed trigger and initiated by a sync trigger The delayed sweep automatically shuts off when the delaying sweep is terminated. This prevents brightening of the sweep retrace in either STROBE position Delayed Triggered or Delayed Armed The brightened sector of the strobe sweep displays are expanded to full scale in either of the DELAYED modes. Automatic provision is made for shut-off of the delaying sweep (NDT) when the delayed sweep (DA) is terminated. This permits maximum duty cycle performance in the DELAYED mode Single Sweep The single sweep mode permits but one driven sweep of the time base to appear on the screen until the delayed sweep (DA) is reset or rearmed The single sweep may be rearmed with a single external trigger pulse, by turning the NDT Trigger Level control or by switching the NDT trigger polarity switch The SWP READY indicator is lit whenever the delayed sweep gate multivibrator is armed and ready to be triggered X Amplifier (for X-Y Displays) When the DISPLAY LOGIC switch is set to X AMP, X Input signals may be applied to X Amplifier via EXT setting of the Trigger SOURCE switch and preferably " — Slope" CALIBRATED DELAY TIME SYSTEM Delay Vernier Control A ten-turn precision potentiometer determines the on-screen distance from the delaying sweep (NDT) start at which the delayed sweep is either triggered or armed CALIBRATED DELAY TIME SYSTEM (Concluded) The DELAY VERNIER control is calibrated to read from zero to 1 0 divisions. This control functions as a Delay Multiplier when used in conjunction with the Delayed TIME/D IV control Accuracy Incremental accuracy of the ten-turn calibrated control is within ±0.25% Delay Zero Control Zero delay is adjustable from the front panel. For extreme accuracy, any or all steps can be adjusted to an external standard from the front panel Delay Range From a minimum of '/4 microsecond to more than 20 seconds TRIGGERING SYSTEM (Separate facilities for each Time Base are provided) HF Recur A unique high-frequency stability switch may be used to improve count down and lock-in of signals having repetition rate of 5 Me or greater. It provides stable synchronization of signals of 1 cm deflection to beyond 50 Me Internal Trigger Signals will trigger from 0.5 div of Y signal up to 1 Me; from 1 div of Y signal up to 10 Me with Types 76-01 A, 76-02A, 76-03 and 76-08 Modules in Y cavity. With the HF STAB control set to RECUR, adjustment of the Trigger LEVEL and HF STAB controls will produce a stable display with 0.2 division of Y signal at 1 Me and 2 divisions of Y signal at 30 Me External Trigger (XI) 0.5 volt peak-to-peak from dc to 1 Me will trigger the sweep; 1 volt peak-to-peak will trigger the sweep to 10 Me. Trigger leveling, slope selection and ac or dc coupling are included. With the HF STAB control set to RECUR, adjustment of the Trigger LEVEL control will produce a stable display with 0.2V to 10V input at 1 Me External Trigger (X10) Same frequency limits as external trigger XI; a 10:1 attenuator is provided to extend the dc leveling capability to ±100 volts dc Trigger Level A range of ±10 volts (nominal) with respect to ground on external triggering Trigger Slope Selection of positive or negative slopes on Internal, Line, or External triggering is available Line Trigger Line frequency triggering can be selected in either polarity and the triggering point may be shifted with the Trig LEVEL control Ext Trig Input Impedance 1 megohm shunted by 40 pf (nominal) AC Coupling High-pass Filter with low-frequency cutoff of 80 cycles DC Coupling Direct coupling is provided to optimize trigger sensitivity when very slow waveforms are applied; to maintain the initial reference position of the trace with respect to the CRT scale at a given trigger level setting; and to avoid trigger point variations due to random repetition rate trigger signals ACF Differentiated trigger input; high-pass Filter is provided to reject hum and low-frequency amplitude modulation; low-frequency cutoff nominally 10 Kc. Signals should rise or fall in less than 100 /¿sec to pass the LF reject Filter Automatic Triggering Visible base line on all sweep ranges when there is no signal input. The sweep free runs until a trigger signal of 10 cps to 10 Me is applied. Application of a trigger signal switches the sweep to the triggered mode immediately HORIZONTAL DEFLECTION SYSTEM Bandwidth Direct Coupled: DC to 2 Me; down 3 db at 2 Me Capacitively Coupled: Low-frequency cutoff is 80 cycles Sensitivity (XI0 Expansion) EXT/X1 Range: 0.1 volt/div EXT/X10 Range: 1 volt/div X Vernier: A ten-to-one attenuator is provided in the horizontal deflection channel to extend the input signal range to 10 volts/div Sensitivity (XT Expansion) Reduces all above sensitivities by 10:1 (Restricted scan) HORIZONTAL DEFLECTION SYSTEM (Concluded) Input Impedance 1 megohm shunted by 40 pf (nominal) Input Connector X AMR front-panel connector is provided to permit use of the horizontal deflection Amplifier for X-Y displays. (DA EXT TRIG connector serves this dual purpose) X Positioning ' A front-panel control permits coarse and fine positioning of the X Input signal or any portion of the sweep to within two divisions of screen center Beam Position Indicator* Two indicator lamps are located on the front panel to alert the operator as to the direction of the beam when it is positioned off the screen

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Service and User Manual
Manual Type:
Service and User Manual
Pages:
80
Size:
4.00 Mbytes (4189174 Bytes)
Language:
english
Revision:
Manual-ID:
67043234
Date:
1965 01 01
Quality:
Scanned document, reading partly badly, partly not readable.
Upload date:
2017 05 07
MD5:
3d4b17c45967a35e0849be7e2bb75a8d
Downloads:
516

Information

1. TECHNICAL SUMMARY - 1.3 1-] Introduction ... - ... ; ... 1-2 Technical Summary (Specifications) ... 2. OPERATING INSTRUCTIONS 2-1 First Time Operation ... 2-1 2-2 Sweep Triggering ... f 2-5 Trigger Source Selection ... 2-4 Trigger Coupling Selection ... 2-5 Trigger Slope Selection ... 2-6 Trigger Level Selection ... 2-7 Sweep Operational Modes ... ¿-JO 2-8 Sweep Expander ... ... 2-11 2-9 Sweep Calibration Adjustment ... £-11 2-10 X-Y Displays ... 2-12 2-11 Gate Output ... 2-12 Sawtooth Output ... 2-13 Time Measurements ... 2-14 Phase-Shift Measurements ... - ... *'15 2-15 Pulse Width Measurements Using the CRT Scale ... : ... 215 2-16 Pulse Width Measurements Using the Delay Vernier Control ... 2-14 2-17 Pulse Jitter Measurements ... 2-14 3. CIRCUIT DESCRIPTION 3-1 Introduction ... 3-2 Trigger Circuit Description ... 3-3 Circuit Description of Normal Sweep ... 3-3 3-4 Circuit Description of Triggered- Strobe Mode ... 3-5 Circuit Description of Delayed- Triggered Mode ... 3-8 3-6 Circuit Description of Armed- Strobe Mode ... 3-8 3-7 Circuit Description of Delayed- Armed Mode ... 3-10 3-8 Horizontal Deflection Circuit Description ... 3-10 4. PERFORMANCE ASSURANCE TEST 4-1 Maintenance Check to Assure Performance ... 4-2 Checking Sweep Calibration ... 4-1 4-4 Checking Normal, Triggered and Armed Sweep Displays ... 4-2 4-5 Delay Calibration Check ... 4-2 4-6 NDT Gate Out Check ... 4-2 4-7 NDT Saw Out Check ... 4-2 4-8 Dual Trace Switch Triggering Check ... 4-2 4-9 Beam Positioning Indicator Check ... 4-3 Section Title P°Se 5. MAINTENANCE AND RECALIBRATION 5-1 Introduction ... •>'} 5-2 Removal and Replacement of Parts ... 5-1 5-3 Servicing Hints ... jj-l 5-4 Gaining Access to Chassis ... 5-5 Test Equipment Required for Service Adjustments ... 5-6 NDT & DA Trig Sens Adjustment ... o-i 5-7 Trig Bal Adjust ... - ... 5-3 5-9 NDT Sweep Length Adjustment ... 5-3 5-11 DA Sweep Length Adjustment ... 5-3 5-12 Sweep Rate Bal Adjustment ... 5-5 5-13 X10 Registration ... 54 5-14 X Amplifier High-Frequency Adjustment ... £-4 5-15 X Ampl DC Balance Adjustment ... 5-4 5-16 Fast Sweep Calibration Adjustment ... 5-& 5-17 Strobe Intensity and Pattern Correction Adjustment ... o-5 5-18 Delay Zero Adjustment ... 5-5 5-19 Delay Cal Adjustment ... 6. PARTS LISTS AND SCHEMATICS 6A Electrical Parts List ... 6-1 6B Spare Parts List ... “-7 List of Recommended Vendors ... 6-9 CHART Sweep Check Calibration Chart ... 4-2

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