Section 4
Theory of Operation
4-12
Figure 4-8. Detector Circuits Block Diagram.
4-63.
Following U7 (TP6) are the low-pass filter selec-
tions. Analog switches U9a through d select the various
filter values for the 30 kHz, 80 kHz, 220 kHz or 500 kHz
low-pass filters. Unity gain buffer U10a completes the
selected filter (TP8). The output of U10a (TP8) is AC
coupled to a final programmable attenuator consisting of
analog switch U11a through d and R27 thorugh R33.
Amplifier U12 is an identical clamped gain stage as U3
and U7 with a gain of 20 dB. The combination of the at-
tenuator and amplifier form a programmable gain stage
with gain selections of X1, X2, X5, and X10.
4-64.
Amplifier U10b and associated components form a
5 Hz high-pass filter which determines the low frequency
bandwidth of the Model 1121A. Buffer amplifier U17 and
CR14, CR15 and R55 present the detector output signal
to the rear panel MONITOR output connector for external
analysis (TP13).
4-65.
The complete detector amplifier and attenuator
chain is programmable for a gain change of 0 to 60 dB in
1X, 2X, or 5X increments. In the distortion and SINAD
modes the 20 dB amplifier on the notch filter plug-in board
increases the chain to a total combined gain of 80 dB. The
programmable gain is required to maintain a constant
level of between 1.2 and 3 volts at the rms, average and
quasi-peak detectors to preserve the resolution and
accuracy of the analyzer over a wide dynamic range. The
rms detector consists of U18 and associated
components. The output of the rms detector (TP15) is a
DC level equal in amplitude to the rms value of the input
signal.
4-66.
The quasi-peak detector consists of U16 and U19
and associated components. U16 forms an integrator with
an attack time of less than 2 ms and decay time of 400
ms. U19 forms an integrator with an attack time of 200 ms
and decay time of 600 ms. The average detector consists
of U15a and b and associated components. U15a forms a
full wave rectifier circuit and C56 filters the output to a DC
level representing the average value of the input signal
(TP14). Analog switch U21 selects either the average or
quasi-peak detector for measurement by one channel of
the A/D converter on the counter plug-in board. Resistors
R37 and R37 balance the gain of the average and rms
detectors to be equal for a sine-wave input waveform.
Inverting amplifier U13b presents a positive 0 to 3 volt
level to the A/D converter (TP7).
Содержание 1121A
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Страница 12: ...VIII MODEL 1121A AUDIO ANALYZER ...
Страница 18: ...Section 1 General Information 1 6 This page intentionally blank ...
Страница 21: ...Installation Section 2 2 3 Figure 2 1 Packing and Unpacking Diagram ...
Страница 22: ...Section 2 Installation 2 4 This page intentionally blank ...
Страница 24: ...Section 3 Operation 3 2 Figure 3 1 Model 1121A Front View Figure 3 2 Model 1121A Rear View ...
Страница 25: ...Operation Section 3 3 3 ...
Страница 26: ...Section 3 Operation 3 4 ...
Страница 27: ...Operation Section 3 3 5 ...
Страница 30: ...Section 3 Operation 3 8 ...
Страница 37: ...Operation Section 3 3 15 TABLE 3 9 ERROR CODES ...
Страница 38: ...Section 3 Operation 3 16 TABLE 3 8 OPTION SWITCH A4S1 ...
Страница 39: ...Operation Section 3 3 17 TABLE 3 9 ERROR CODES ...
Страница 41: ...Operation Section 3 3 19 ...
Страница 42: ...Section 3 Operation 3 20 ...
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Страница 50: ...Section 4 Theory of Operation 4 4 Figure 4 3 CPU Circuits Block Diagram ...
Страница 62: ...Section 4 Theory of Operation 4 16 This page intentionally blank ...
Страница 64: ...Section 5 Maintenance 5 2 ...
Страница 71: ...Maintenance Section 5 5 9 TABLE 5 3 ANALYZER DC LEVEL ACCURACY TEST RECORD ...
Страница 73: ...Maintenance Section 5 5 11 TABLE 5 4 ANALYZER AC LEVEL ACCURACY TEST RECORD ...
Страница 74: ...Section 5 Maintenance 5 12 TABLE 5 5 ANALYZER AC LEVEL FLATNESS TEST RECORD ...
Страница 76: ...Section 5 Maintenance 5 14 TABLE 5 9 SOURCE LOW LEVEL ACCURACY TEST RECORD ...
Страница 77: ...Maintenance Section 5 5 15 TABLE 5 12 FILTER ACCURACY TEST RECORD ...
Страница 78: ...Section 5 Maintenance 5 16 TABLE 5 14 RESIDUAL SIGNAL TO NOISE TEST RECORD ...
Страница 79: ...Maintenance Section 5 5 17 ...
Страница 80: ...Section 5 Maintenance 5 18 TABLE 5 17 CCIR FILTER ACCURACY TEST RECORD ...
Страница 81: ...Maintenance Section 5 5 19 TABLE 5 18 A WEIGHTING FILTER ACCURACY TEST RECORD ...
Страница 82: ...Section 5 Maintenance 5 20 ...
Страница 83: ...Maintenance Section 5 5 21 ...
Страница 84: ...Section 5 Maintenance 5 22 ...
Страница 90: ...Section 5 Maintenance 5 28 TABLE 5 23 DIAGNOSTIC ERROR CODE DESCRIPTION ...
Страница 92: ...Section 6 Parts List 6 2 Figure 6 1 Model 1121A Programmable Audio Analyzer ...
Страница 93: ...Parts List Section 6 6 3 ...
Страница 94: ...Section 6 Parts List 6 4 Figure 6 2 1121A Frame Assy Sheet 1 of 2 ...
Страница 95: ...Parts List Section 6 6 5 Figure 6 2 1121A Frame Assy Sheet 2 of 2 ...
Страница 97: ...Parts List Section 6 6 7 Figure 6 3 PWA 1121A Input A0 ...
Страница 100: ...Section 6 Parts List 6 10 Figure 6 4 PWA 1121A Main Filter A1 ...
Страница 102: ...Section 6 Parts List 6 12 Figure 6 5 PWA 1121A Notch A2 ...
Страница 105: ...Parts List Section 6 6 15 Figure 6 6 PWA 1121A Detector A3 ...
Страница 109: ...Parts List Section 6 6 19 Figure 6 7 PWA 1121A Freq Counter ...
Страница 111: ...Parts List Section 6 6 21 Figure 6 8 PWA 1121A CPU A5 ...
Страница 113: ...Parts List Section 6 6 23 Figure 6 9 PWA 1121A Source A6 ...
Страница 114: ...Section 6 Parts List 6 24 ...
Страница 115: ...Parts List Section 6 6 25 ...
Страница 116: ...Section 6 Parts List 6 26 Figure 6 10 PWA 1121A Output A7 ...
Страница 119: ...Parts List Section 6 6 29 Figure 6 11 Front Bezel Assy A17 ...
Страница 120: ...Section 6 Parts List 6 30 Figure 6 12 PWA 1121A Keyboard A13 ...
Страница 122: ...Section 6 Parts List 6 32 Figure 6 13 Bezel Sub Assy ...
Страница 123: ...Parts List Section 6 6 33 Figure 6 14 PWA 1121A Display A12 ...
Страница 126: ...Section 6 Parts List 6 36 Figure 6 15 Front Panel Assy ...
Страница 127: ...Parts List Section 6 6 37 Figure 6 16 Rear Panel Assy A21 Sheet 1 of 2 ...
Страница 128: ...Section 6 Parts List 6 38 Figure 6 16 Rear Panel Assy A21 Sheet 2 of 2 ...
Страница 129: ...Parts List Section 6 6 39 Figure 6 17 Heat Sink Assy A20 ...
Страница 131: ...Parts List Section 6 6 41 Figure 6 18 Power Amplifier A24 ...
Страница 132: ...Section 6 Parts List 6 42 Figure 6 19 Transformer Assy T1 ...
Страница 133: ...Parts List Section 6 6 43 Figure 6 20 1121A Card Cage Assy A18 ...
Страница 134: ...Section 6 Parts List 6 44 Figure 6 21 PWA 1121A Mother A10 ...
Страница 137: ...Parts List Section 6 6 47 Figure 6 22 PWA 400 Hz High Pass Filter ...
Страница 138: ...Section 6 Parts List 6 48 ...
Страница 139: ...Schematic Diagrams Section 7 7 1 SECTION VII SCHEMATIC DIAGRAMS TABLE 7 1 LIST OF SCHEMATICS ...
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Страница 141: ...Schematic Diagrams Section 7 7 3 Figure 7 1 Main Frame Schematic ...
Страница 142: ...Section 7 Schematic Diagrams 7 4 Figure 7 2 Input Board A0 Parts Location Diagram ...
Страница 143: ...Schematic Diagrams Section 7 7 5 Figure 7 3 Input Board A0 Schematic ...
Страница 144: ...Section 7 Schematic Diagrams 7 6 Figure 7 4 Filter Board A1 Parts Location Diagram ...
Страница 145: ...Schematic Diagrams Section 7 7 7 Figure 7 5 Filter Board A1 Schematic ...
Страница 146: ...Section 7 Schematic Diagrams 7 8 Figure 7 6 Notch Board A2 Parts Location Diagram ...
Страница 147: ...Schematic Diagrams Section 7 7 9 Figure 7 7 Notch Board A2 1Schematic ...
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Страница 149: ...Schematic Diagrams Section 7 7 11 Figure 7 8 Notch Board A2 2 Schematic ...
Страница 150: ...Section 7 Schematic Diagrams 7 12 Figure 7 9 Detector Board A3 Parts Location Diagram ...
Страница 151: ...Schematic Diagrams Section 7 7 13 Figure 7 10 Detector Board A3 1 Schematic Figure 7 11 Detector Board A3 2 Schematic ...
Страница 152: ...Section 7 Schematic Diagrams 7 14 Figure 7 12 Counter Board A4 Parts Location Diagram ...
Страница 153: ...Schematic Diagrams Section 7 7 15 Figure 7 13 Counter Board A4 Schematic ...
Страница 154: ...Section 7 Schematic Diagrams 7 16 Figure 7 14 C P U Board A5 Parts Location Diagram ...
Страница 155: ...Schematic Diagrams Section 7 7 17 Figure 7 15 C P U Board A5 Schematic ...
Страница 156: ...Section 7 Schematic Diagrams 7 18 Figure 7 16 Source Board A6 Parts Location Diagram ...
Страница 157: ...Schematic Diagrams Section 7 7 19 Figure 7 17 Source Board A6 1 Schematic ...
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Страница 159: ...Schematic Diagrams Section 7 7 21 Figure 7 18 Source Board A6 2 Schematic ...
Страница 160: ...Section 7 Schematic Diagrams 7 22 Figure 7 19 Output Board A7 Parts Location Diagram ...
Страница 161: ...Schematic Diagrams Section 7 7 23 Figure 7 20 Output Board A7 Schematic ...
Страница 162: ...Section 7 Schematic Diagrams 7 24 Figure 7 21 Mother Board A10 Parts Location Diagram ...
Страница 163: ...Schematic Diagrams Section 7 7 25 Figure 7 22 Mother Board A10 Schematic ...
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Страница 165: ...Schematic Diagrams Section 7 7 27 Figure 7 25 Power Supply A11 2 Schematic ...
Страница 166: ...Section 7 Schematic Diagrams 7 28 This page intentionally blank ...
Страница 167: ...Schematic Diagrams Section 7 7 29 ...
Страница 168: ...Section 7 Schematic Diagrams 7 30 Figure 7 26 Display Board A12 Parts Location Diagram ...
Страница 169: ...Schematic Diagrams Section 7 7 31 Figure 7 27 Display Board A12 Schematic Sheet 1 ...
Страница 170: ...Section 7 Schematic Diagrams 7 32 Figure 7 28 Key Board A13 Parts Location Diagram ...
Страница 171: ...Schematic Diagrams Section 7 7 33 ...
Страница 172: ...Section 7 Schematic Diagrams 7 34 ...
Страница 173: ...Schematic Diagrams Section 7 7 35 ...
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Страница 176: ...Section 7 Schematic Diagrams 7 38 Figure 7 35 CCITT Board A1A31 Schematic ...
