Theory of Operation
TDS 340A, TDS 360 & TDS 380 Technical Reference
3–15
A26 Monitor Assembly
The A26 Monitor Assembly displays all information (waveforms, text, grati-
cules, and pictographs). It generates the high voltages necessary to drive the
display tube. It also contains the video amplifier, horizontal oscillator, and the
vertical and horizontal yoke driver circuitry.
The 640 by 480 pixel raster scan cathode-ray tube (CRT) display has 60 Hz
frame and 31.5 kHz line rates. This CRT display circuitry is similar to a
television monitor.
Inputs, Video, and Vertical Deflection.
The +12 V regulator is a three-terminal
regulator (U130).
The Vertical Yoke Winding Driver provides the scan current (ramp) for the
vertical (field) deflection coil. A vertical sync signal, a negative pulse at the
deflection rate, causes the ramp to “retrace” to the top of the CRT screen.
A large pulse is generated during vertical retrace. A portion of this signal drives
the G1 grid 50 V more negative than normal during the retrace period. This
keeps retrace lines blanked even when the background is visible.
The Video Amplifier amplifies the input video signal, and drives the cathode of
the CRT.
Horizontal Deflection, CRT, and High Voltage.
The Horizontal Oscillator Control
generates the “switch” controlling signal and synchronizes the scan to the
horizontal sync input signal. IC U370 includes a horizontal oscillator, a phase
detector, and an output shaper
The circuit is a phase-locked loop. The differentiated horizontal sync is the
reference signal, and the retrace or flyback pulse (U370 pin 4) is the feedback
signal to be locked to the horizontal sync (HORIZONTAL YOKE) signal.
Horiz Yoke Winding Driver transistor Q160, along with Q260 and T170,
provides the deflection coil currents.
Transformer T210 generates the CRT high voltage from the large voltage pulse
that occurs during horizontal retrace (flyback pulse). Other secondary voltages
are also derived from the flyback pulse.
Summary of Contents for TDS 340A
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Page 12: ...Contents viii TDS 340A TDS 360 TDS 380 Technical Reference ...
Page 16: ...Service Safety Summary xii TDS 340A TDS 360 TDS 380 Technical Reference ...
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Page 42: ...Operating Information 2 10 TDS 340A TDS 360 TDS 380 Technical Reference ...
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Page 49: ...Theory of Operation 3 6 TDS 340A TDS 360 TDS 380 Technical Reference ...
Page 59: ...Theory of Operation 3 16 TDS 340A TDS 360 TDS 380 Technical Reference ...
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Page 82: ...Performance Tests 4 22 TDS 340A TDS 360 TDS 380 Technical Reference ...
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Page 91: ...Adjustment Procedures 5 8 TDS 340A TDS 360 TDS 380 Technical Reference ...
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Page 140: ...Troubleshooting 6 48 TDS 340A TDS 360 TDS 380 Technical Reference ...
Page 142: ...Repackaging Instructions 6 50 TDS 340A TDS 360 TDS 380 Technical Reference ...
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Page 206: ...Electrical Parts List 8 58 TDS 340A TDS 360 TDS 380 Technical Reference ...
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Page 210: ...TDS 340A 360 380 OPTION BOARD BLOCK DIAGRAM A2 0 ...
Page 211: ......
Page 212: ...OPTION BUS AND GPIB A2 TDS 340A 360 380 1 ...
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Page 214: ...TDS 340A 360 380 ROM PRINTER AND RS 232 A2 2 ...
Page 216: ...PRINTER POWER A3 1 TDS 340A 360 380 OPTION 14 ...
Page 218: ...A5 1 FLOPPY INTERFACE TDS 340A 360 380 ...
Page 222: ...CPU A6 TDS 340A 360 380 1 ...
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Page 224: ...A6 TDS 340A 360 380 2 FPP POTS ...
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Page 226: ...LEDS DRIVER A6 TDS 340A 360 380 3 ...
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Page 228: ...SWITCHES A6 TDS 340A 360 380 4 ...
Page 233: ...9 26 TDS 340A TDS 360 TDS 380 Technical Reference ...
Page 234: ...ROOT SHEET A11 A12 TDS 340A 360 0 ...
Page 235: ......
Page 236: ...TRIGGERS A11 A12 TDS 340A 360 1 TDS 340A ...
Page 237: ......
Page 238: ...ATTENUATORS A11 A12 TDS 340A 360 2 TDS 340A TDS 340A ...
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Page 240: ...TRIGGER LOGIC AND TIME INTERPOLATOR A11 A12 TDS 340A 360 3 ...
Page 241: ......
Page 242: ...TIME BASE CONTROLLER A11 A12 TDS 340A 360 4 ...
Page 243: ......
Page 244: ...SAMPLER A11 A12 TDS 340A 360 5 ...
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Page 246: ...CPU A11 A12 TDS 340A 360 6 TDS 340A ...
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Page 248: ...DISPLAY A11 A12 TDS 340A 360 7 ...
Page 252: ...MAIN BLOCK DIAGRAM A13 TDS 380 0 MAIN BOARD 671 3753 00 389 2154 00 ...
Page 253: ......
Page 254: ...TRIGGERS A13 TDS 380 1 ...
Page 255: ......
Page 256: ...ATTENUATORS A13 TDS 380 2 ...
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Page 258: ...TRIGGER LOGIC AND TIME INTERPOLATOR A13 TDS 380 3 ...
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Page 260: ...TIMEBASE A13 TDS 380 4 ...
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Page 262: ...SAMPLER A13 TDS 380 5 ...
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Page 264: ...CPU A13 TDS 380 6 ...
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Page 266: ...DISPLAY A13 TDS 380 7 ...
Page 269: ...9 62 TDS 340A TDS 360 TDS 380 Technical Reference ...
Page 270: ...MONITOR BLOCK DIAGRAM A26 TDS 340A 360 380 0 ...
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Page 272: ...INPUTS VIDEO AND VERTICAL DEFLECTION A26 TDS 340A 360 380 1 ...
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Page 286: ...Mechanical Parts List 10 12 TDS 340A TDS 360 TDS 380 Technical Reference ...
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