Tektronix 7844 Instruction Manual
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Tektronix 7844 Instruction Manual

Tektronix 7844 Instruction Manual

Dual-bea oscilloscope
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Table of Contents

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THE FOLLOWING SERVICING INSTRUCTIONS
ARE FOR USE BY QUALI FI ED PERSONNEL ONLY.
TO
AVOID
PERFORM ANY SERVICING OTHER THAN THAT
CONTAINED IN OPERATING INSTRUCTIONS
UNLESS YOU ARE QUALI FI ED TO DO SO.
Tektronix, Inc.
500
P.O. Box
97077
Beaverton, Oregon
070-1676-02
Product Group
42
WARNING
PERSONAL
INJURY,
PLEASE CHECK FOR CHANGE INFORMATION
AT THE REAR OF THIS MANUAL.
7844/R7844
DUAL-BEA
OSCILLOSCOPE
INSTRUCTION
COMMITTED TO EXCELLENCE
DO
NOT
I TH OPTIO S
SERVICE
MANUAL
Serial Number
First Printing SEP
Revised OCT
1974
1981

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Summary of Contents for Tektronix 7844

  • Page 1 INJURY, PERFORM ANY SERVICING OTHER THAN THAT CONTAINED IN OPERATING INSTRUCTIONS UNLESS YOU ARE QUALI FI ED TO DO SO. PLEASE CHECK FOR CHANGE INFORMATION AT THE REAR OF THIS MANUAL. 7844/R7844 DUAL-BEA OSCILLOSCOPE I TH OPTIO S SERVICE INSTRUCTION MANUAL Tektronix, Inc.
  • Page 2 Products of Tektronix, Inc. and its subsidiaries are � covered by U.S. and foreign patents and/or pending patents. TEKTRONIX, TEK, SCOPE-MOBILE, and registered trademarks of Tektronix, Inc. TELEQUIP­ MENT is a registered trademark of Tektronix U. K. Limited. Printed U.S.A. Specification price change privileges are reserved.

  • Page 3: Table Of Contents

    THEORY OF OPERATION Tektronix Field Service ... 4-1 Block Diagram ....3-1 Using This Procedure .

  • Page 4: Introduction

    7844/R7844 Service TABLE OF CONTENTS (cont) Page Page Section 5 ADJ USTMENT PROCEDURE Troubleshooting . . . Troubleshooting Equipment . . 6-3 Preliminary Information . . Adjustment Interval Troubleshooting Techniques Tektronix Field Service . 5-1 Corrective M aintenance . Using This Procedure . .
  • Page 5 Detailed block diagram of the Beam 1 Hori­ 3-20 1 -1 7844 dimensional drawing ....1 -1 3 zontal Amplifier circuit (for instruments 7844 1 -2 R7844 dimensional drawing ... . 1 -1 4 SN B1 09999-below;...
  • Page 6 Readout display with Q2225 removed ..5-35 9-23 A28-Cap-Rectifier circuit board assembly 7844/R7844 troubleshooting chart ..6-4 9-24 A29-Low-Voltage Regulator circuit board Power unit securing screws ... . 6-8...
  • Page 7 1 -1 1 -2 7844/R7844 Oscilloscope System Vertical Adjustment Summary ....Specification ......
  • Page 8 7844/R7844 Service OPERATORS SAFETY SUMMARY The general safety information in this part of the summary is for both operating and servicing personnel. Specific warnings and cautions will be f ound throughout the manual where they apply, but may not appear in this summary.
  • Page 9 7844/R7844 Service SERVICING SAFETY SUMMARY FOR QUALIFIED SERVICE PERSONNEL ONL Refer also to the preceding Operators Safety Summary. Disconnect power before removing protective panels, Do Not Service Alone soldering, or replacing components. Do not perform internal service or adjustment of this...
  • Page 10 7 844 / R78 44 Se rvic e 784 4 DU AL- BE AM OSC ILL OSC R78 44 OPT IO N DU AL- BE AM O SCI LL OSC 167 5-1 2 viii REV JUN 198 1...
  • Page 12 RIGHT LEFT LEFT RIGHT RIGHT RIGHT R IGHT LEFT 7844/R7844 Option 21 only Within 0.5 div of graticule center Vertical Centering Beam 1 trace can be positioned Vertical Separation Control Range at least 4 and 4 div with (deleted by Option 2 1 )
  • Page 13 M inimum Photographic After 5 minutes phosphor delay time Writing Speed with Type 47 Polaroid Film (without film fogging) P-l l phosphor Tektronix with 1 .5 cm/ns fl .2 Lens and 1 :0.5 Object- to-Image Ratio (with 3000 ASA Polaroid Film)
  • Page 14 R7844 40 mA Available through CALI BRATOR output with optional bnc-to-Current Loop Adapter, Tektronix Part No. 01 2-0341 -00. CALIBRATOR Switch must be set to the 4 V position for 40 mA output Amplitude Accuracy Within 1 % (p-p voltage and current) Repetition Rate 1 kHz within 0.25%...
  • Page 15 Specification-7844/R7844 Service Table 1 - 1 (cont) Supplemental Information Characteristic Performance Requirement B SAWTOOTH Time-base unit in B HORIZ Compartment Source Positive-going with baseline at 0 V Polarity within 1 V (into 1 Mn) Output Voltage Rate of Rise Into 50 n...
  • Page 16 HIGH, LOW, OFF The three-position switch is located on plug-in units only) the left side-panel of the R7844 and on the rear panel of the 7844 SINGLE SWEEP RESET (rear Bnc connector; remote single-sweep panel) reset (A and B HORIZ) with compatible...
  • Page 17 Specification-7844/R7844 Service Table 1 - 1 (cont) Supplemental Information Performance Requirement Characteristic SING LE SWEEP RESET (cont) Switching from the high level ( + 50 V Signal Required to + 1 0 V ; low level (+0.5 V to -5 V ; sink less...

  • Page 18: System Electrical Specification

    SYSTEM ELECTRICAL SPECIFICATION S-Sampling unit T -Sampling time-base unit Your TEKTRON I X 7844/R7844 oscilloscope system pro­ vides exceptional flexibility in operation with a wide choice The third and fourth digits of the plug-in type number of general and special purpose plug-in units. The type num­...
  • Page 19 Specification-7844/R7844 Service Table 1-2 7844/R7844 OSCILLOSCOPE SYSTEM VERTICAL SPECIFICATION Accuracy· EXT CAL INT CAL Amplifier O°C to SO°C O°C to SO°C Ri5etime Bandwidth Plug-In Probe (MHz) (n5) Unit 1 .S 7A1 1 Integral None 1 05 7A1 3 1 .5...
  • Page 20 Specification-7844/R7844 Service Table 1 -�3 lists the horizontal specifications that are sys­ Table 1 -4 tem dependent. For more complete specifications on plug-in SPECIAL PURIf'OSE AND SAMPLING PLUG-IN UNITS units for thE! 7000-Series Oscilloscope System, refer to the Tektronix Products Catalog.
  • Page 21 Specification- 7844/R7844 Service Table 1 -5 ENVIRONMENTAL Information Characteristic NOTE This instrument will meet the electrical characteristics given in the Perform,mce Requirement column of T able 1 - 1 over the following environmental limits. Temperature Range O°C to +50°C Operating Non-Operating - 55°C to + 75°C...

  • Page 22: Standard Accessories

    1 6.3 f,g 1 5.0 kg NOTE See Fig. 1 - 1 for 7844 dimensional drawing. Refer to Fig. 1-2 for the R7844 o' i mensional drawing. STANDARD ACCESSORIES are given in the Heplaceable Mechanical Parts list in this manual. For optional accessories available for use with this Standard accessories supplied with the 7844 and R7844 instrument, see the Tektronix Products Catalog.
  • Page 23 000000 0 DODO • 0 000 ot U ..· 0 '- N ' c:i�"" Mil) !lIu .-� ... u ·co ID U Mil) N O ' r=ltt Fig. 1 - 1 . 7844 dimensional drawing. 1 - 1 3...

  • Page 24: R7844 Dimensional Drawing

    Specification-7844/R7844 Service 000 00 � 00 0 00 ��[[J] �II o� - - - -t- ' : I � . Fig. 1-2. R7844 dimensional drawing. 1 - 1 4...

  • Page 25: Operating Information

    The This instrument has a three-wire power cord with a 7844/R7Ei44 operates from a 1 1 5 V or 230 V (50 Hz to three-terminal polarized plug for connection to the 400 Hz) nominal line source.

  • Page 26: Front-Panel Controls And Connectors

    Operating Illforrnation-7844/R7844 Service 1 6 7 5·9 Fig. 2- 1. Front-panel controls and connectors. REV JUN 1 981...

  • Page 27: Front-Panel Controls, Connectors, And Indicators

    BEAM 1 FOCUS Control-Provides optimum defini­ tion of beam 1 display. Current Loop (not marked) 7844-Provides 40 rnA square-wave current (1 kHz) when the CALIBRATOR switch is set to 40 rnA CALI BRATOR Connector-Provides 1 kHz calibrated position. square-wave voltages.

  • Page 28: Rear-Panel Controls And Connectors

    Operating Inforrnation-7844/R7844 Service ® RE AR- PANEL CONTROLS AND ENHANCER PRESET Adjustment 1 (Option 22 only; CONNECTORS not sI10wn). ® MAIN and DLY'D (A GATE) Switch-Selects between B TF:IG SOU RCE Control-Selects LEFT V ERT or main and delay gates from time base unit in A HORIZ compartment.

  • Page 29: Rear-Panel Controls And Connectors

    Operating Information-7844/R7844 Service • • • 1 6 7 5· 1 0 Fig. 2-2. Rear-panel controls and connectors. REV JUN 1 98 1...

  • Page 30: Operating Temperature

    The 7844 is cooled by air drawn in through holes in the compartment. Insert the plug-in unit into the compartment side and bottom panels and blown out through the fan until it locks into place.

  • Page 31: Theory Of Operation

    INTRODUCTION This section of the manual decribes the circuitry used in the 7844/R7844 Oscilloscope. The description begins with a discussion of the instrument, using the block diagram shown in the Diagrams section at the back of this manual. Next, each circuit is described in detail with supporting illustrations, when appropriate, to show the relationship between the stages in each major circuit.

  • Page 32: Detailed Circuit Operation

    This section provides a description of the electrical oper­ device. ation and relationships of the circuits in the 7844/R7844. Circuits commonly used in the electronics industry are not described in detail. If more information is desired on these...

  • Page 33: Crossover Mode Switch

    Theory of Operation-7844/R7844 Service mately 0.6 V more negative than the level at its base, 0908 Crossover Mode Switch becomes forward biased and its emitter rapidly rises posi­ The Crossover Mode Switch circuit includes front-panel tive. Since C902 cannot change its charge instantaneously,...

  • Page 34: Detailed Block Diagram Of Crossover Mode Switch Circuits

    Theory of Operation-7844/R7844 Service S3161 A T R I G S3163 B TR IG SOURCE R3185 V E R T SEP ( 1 ) V E R T SEP TO BEAM 1 CONTROL V E RTICAL AMPLI F I E R...

  • Page 35: Logic Stage

    Theory of Operation-7844/R7844 Service VERT SEP ( 1 ) Control End of AS Mode. The End of AB Control stage detects End of AS operation. A complete discussion of End of AB Logic The front-panel VERT SEP ( 1 ) control provides vertical...
  • Page 36 Theory of Operation-7844/R7844 Service BEAM D I SP LAYED OUTPUT AT P31 29 � � V E RTICAL � � � � � MODE MODE f -S � o -S A.. � A.. � � � -S � -S o:r A..

  • Page 37: Dedicated Mode Switch (Option 21 Only)

    Theory o f Operation-7844/R7844 Service VERT compartment is dedicated to the vertical deflection of Readout Display Logic beam 2 . The Dedicated Mode Switch circuits operate in con­ The Readout Display Logic stage produces vertical and junction with the Logic circuits (diagram 5) to develop con­...

  • Page 38: Detailed Block Diagram Of Dedicated Mode

    Theory of Operation-7844/R7844 Service S 1 6 1 A TR I G SOU RCE TRIGGER S163 SE LECTOR B TR I G S 1 59 <3>0 � BEAM 2 HOR IZONTAL HOR IZONT AL MODE MODE HO R I ZONTAL...
  • Page 39 The trace separa­ tion current is added to the beam 1 and beam 2 vertical amplifiers in the 7844/R7844 Oscilloscope. Separate Y-axis When the A Horizontal time base is selected for beam 2 amplifiers are provided for four display possibilities: ( 1 )
  • Page 40 Theory of Operation-7844/R7844 Service reverse biased. The level at pin 1 4 also drops negative to or selected. A block diagram of the Logic circuit is shown in complete the cycle. Once again, C21 0 begins to charge the Diagrams section.
  • Page 41 Theory of Operation-7844/R7844 Service 2 MHz F R E E-RUNNING OSC I L LATOR PIN 1 3 PI N 1 4 DE LAY RAMP ( 8) <y (A) U205 - 1 5 V 1 6 .,6- 1 2 Fig. 3·6. (A) Diagram o f Clock Generator stage; ( B ) Idealized waveforms for Clock Generator stage.
  • Page 42 5 V level through R240 to pin 1 0. The direct-clear 11.1 , At the end of A Horizontal sweep, the HI holdoff level at input, at pin 1 3, is held inactive when the 7844/R7844 is not circuit board pin is inverted by U233A and inverted again operating in the X-Y mode.

  • Page 43: Nate Switching

    Integrated circuit U265 provides alternate sation signal at circuit board pin G is LO, the 7844/R7844 is operating in the X- Y mode. That is, either an amplifier unit is switching for the Left Vertical plug-in unit and U275 pro­...
  • Page 45 3-9.) The Horizontal Logic stage (U285) provides the alternate switching signal when the 7844/R7844 is operating in the X­ Y mode. That is, either an amplifier unit is operating in a A HI level at U265 pin 13 indicates that the Left Vertical...

  • Page 46: Logic

    Logic. When base units installed in the A HORIZ and B HORIZ 7844/R7844 is operating in an intensified mode, with a de­ compartments. laying time-base unit in the A HORIZ compartment and a delayed time-base unit in the B HORIZ compartment, cur­...

  • Page 47: Functional Diagram Of Beam 2 Z-Axis Logic

    Theory of Operation-7844/R7844 Service V ERT compartment, to modulate the display intenSity. Di­ be operating at a time. When the A Horizontal time-base odes CR331 and CR332 limit the maximum voltage change unit has been selected for beam 1 display, the LO level (ap­...
  • Page 48 When A LO level is present at circuit board pin V when the time­ 7844/R7844 is operating in an intensified mode, with a de­ base unit in the A HORIZ compartment is operating in the laying time-base 'unit in the A HORIZ compartment and a independent mode.

  • Page 49: Crossover Vertical Interface

    Theory of Operation-7844/R7844 Service FROM B TR I G SOURCE B T R I G G E R T R I G G E R S I GNAL AMPLI F I E R SW ITCH TR IGG E R SIGNAL...

  • Page 50: Detailed Block Diagram Of The Crossover Ver

    Theory of Operation-7844/R7844 Service signals to the Beam 1 Vertical Amplifier and to the Beam 2 Emitter follower transistors 03702 and 03704 form the Vertical Amplifier (four total). The Readout Inhibit stage dis­ input buffer stagE! for the vertical signal from the RIGHT ables the Beam 2 Preamplifiers during the readout display.
  • Page 52 Theory of Operation-7844/R7844 Service BEAM 1 V E RTICAL SIGNAL V E RTICAL SIGNAL V E RTICAL F R OM PR EAMP L I F I E R BEAM 1 L E F T V E RTICAL U6 1 5...
  • Page 53 T heory of Operation-7844/R7844 Service V E RTICAL SI GNAL H I G H TO BEAM 1 BEAM 1 V E RTICAL OUTPUT DE L AY - L I N E F R EOU ENCY V E RTICAL SIGNAL F R OM...

  • Page 54: Beam 2 Vertical Amplifier

    Theory of Operation-7844/R7844 Service The signal at the output collectors of U 1 745 is connected accepts the auxiliary Y-axis input from the Main Interface circuit (diagram 4). Figure 3-1 7 shows a block diagram of directly to the beam 1 vertical deflection plates of the crt. A...

  • Page 55: Detailed Block Diagram Of The Horizontal In

    Theory of Operation-7844/R7844 Service � Horizontal Int,erface The beam 2 auxiliary Y-axis signal originates from dual time-base units with altornate sweep switching and vertical The Horizonltal I nterface circuit determines whether the positioning. Refer to the Auxiliary Y-Axis Switching portion...
  • Page 56 SIGNAL FROM BEAM 1 BEAM FINDER (1 676-1 77)1676-195 Fig. 3- 1 9. Detailed block diagram of the Beam Horizontal Amplifier circuit (for instruments 7844 SN B 1 1 GOGO-above; R7844 SN B 1 00000-above). 3-26 REV JUN 1 981...
  • Page 57 'Theory of Operation-7844/R7844 Service � through R481 0. This occurs when the same horizontal plug­ Beam 1 Hori4�ontal Amplifier in compartment is selected by the BEAM 1 and BEAM 2 R7844 7844 SN HORIZONTAL MODE switches. The Horiz Ctr adjustment, (For instruments B 1 09999-below;...

  • Page 58: Detailed Block Diagram Of The Beam 1 Hori

    BEAM F I N O E R 0 0 0 16 7 6 ·9 1 Fig. 3-20. Detailed block diagram of the Beam 1 Horizontal Amplifier circuit (for instruments 7844 SN B 1 09999-below; R7844 SN B099999-below). Similarly, to prevent the Right Output Amplifier from be­...

  • Page 59: Horizontal Interface

    R5809 BEAM 2 BEAM FINDER (1 676-1 78)1676-196 Fig. 3-2 1 . Detailed block diagram of the Beam 2 Horizontal Amplifier circuit (for instruments 7844 SN B 1 1 0000-above; R7844 SN B 1 00000-above). REV JUN 1 981 3-29...

  • Page 60: Detailed Block Diagram Of The Beam 2 Hori

    Theory of Operation-7844/R7844 Service within the Beam 2 Horizontal Amplifier. Also, the Beam 2 justment R5804 to ground. Grounding the center tap of Horizontal Amplifuer component numbers are in the 2000- R5804 allows R5804 to horizontally position the readout series whereas the Beam 1 Horizontal Amplifier component display on the crt.

  • Page 61: Z-Axis Amplifiers

    'Theory of Operation-7844/R7844 Service � U231 5. The applied voltage to the input of U231 5 from the Z-Axis Amplifiers � high-voltage secondary of T 1 3 1 0 is approximately 3 k The Beam 1 and Beam 2 Z-Axis Amplifier circuits provide peak to peak.
  • Page 62 Theory of Operation-7844/R7844 Service � BEAM CURRENT SENSE (I SENSE) TO CONVERTER/RECT I F I E R S ANODE +21 kV V2425 VOLTAGE CATHODE-RAY M U LT I P L I E R TUBE U23 1 5 TRACE ROTATION FROM...
  • Page 63 Theory of Operation-7844/R7844 Service Control Grid DC Restorer Circuits. The dc restorer circuits are bias supplies for the beam 1 and beam 2 focus grids. The outputs of these stages are The Beam 1 and Beam 2 Control Grid DC Restorer cir­...

  • Page 64: Output Signals

    Theory of Operation-7844/R7844 Service The Beam 2 Auto Focus Amplifier includes 02488, the negative-goin9 gate signal turns 01 01 2 off. Then 01 01 8 02486, 02480, and 02490 connected as a non-inverting turns on and a positive level is produced at the collector of operational amplifier to drive the focus-grid electrode of the 01 01 8.
  • Page 65 'Theory of Operation-7844/R7844 Service Display Format Up to eight words of readout information can be dis­ LEFT VERT RIGHT VERT A HaRIZ B HaRIZ CHANNEL CHANNEL 1 CHANNEL 1 CHANNEL played on the crt. The position of each word is fixed and is directly related to the plug-in unit from which it originated.
  • Page 66 � � " C '() C - l C -2 C -3 C -4 C -6 C -8 C - l 0 NUMBER O· � � ..C U R R E NT � (M I L L I - 0 .
  • Page 67 Theory of Operation-7844/R7844 Service The analog outputs of the Column Data Switch and Row necting resistors between them and the time-slot input lines. Data Switch are connected to the Column Decoder and The resultant output is a sequence of 1 0 analog current Row Decoder stages, respectively.

  • Page 69: U21 26

    Theory of Operation-7844/R7844 Service The Z Readout output at pin 1 2 is produced next. This current is connected to the crt circuit to unblank the crt to the intensity level determined by the READOUT INTENSITY CHARAt:TER control. The Character Scan ramp at pin 1 6 started to go SC.ll , N...

  • Page 70: Timer Stage Operation When Display-Skip

    Theory of Operation-7844/R7844 Service positive voltage switches the stage to the same conditions as were present under the Display-Skip condition. There­ fore, the crt display is not interrupted to present characters. However, time-slot pulses continue to be generated. PIN I;...
  • Page 72 Theory of Operation-7844/R7844 Service Readout CClintrol Single-Shot Lockout I ntegrated circuit U21 20 makes up the Single-Shot The primary readout controls, located on the front panel, Lockout stage. This stage allows a single readout frame are shown on the Calibrator board (diagram 1 ). In the follow­...

  • Page 74: Idealized Current Waveforms Of (A) Row Ana

    Theory of l:)peration-7844/R7844 Service The final data output is provided from time-slot 9 by R 1 90 connected to the column output and R90 to the row output. These resistors encode two units of column current and four units of row current to cause a V (volts) to be displayed.

  • Page 77: Typical Output Waveforms For Zeros Logic And Memory Stage Operation

    Theory of Operation-7844/R7844 Service T I M E -SLOTS I N PUT P I N OF U2232 ACT I VATED COMMAND I ... I . I I . , 'T I . I • I I 09 1 0l 1 � 1...
  • Page 78 Theory of Operation-7844/R7844 Service be shifted from m (1 00 /lA column current, column 1 ) to no the characters shown in the Character Selection Matrix can be displayed by correct addressing of the row and column. prefix (0 column current, column 0) so only the unit of mea­...

  • Page 79: Converter/Rectifiers

    Theory of Operation-7844/R7844 Service DECIMAL�O I NT LOCATION ENCODED D U R I N G THIS TlME .sLOT -- NO DISPLAY F I RST POSSI BLE CHARACTE R DIS­ TION F I RST NUMBER OF MEASUR EM EN T NORMALL Y DISPLAYED A T TH IS LOCATION .

  • Page 80: Flow Chart For Character Generation By The Readout System

    Theory of Clperation-7844/R7844 Service GENERATE DISPLAY -SKIP OUTPUT (SHORTENS TIM E-SLOT PERIOD) UNBLANK CRT �� �� � LEVEL RESET CHARACTER POSITION COUNTE R AND ZEROS LOGIC AND MEMORY SWITCH BEAM 2 CRT DISPLAY SOURCE FROM PLUG·INS ADVANCE CHANNEL TO READOUT...

  • Page 81: Low-Voltage Regulators

    Theory of Operation-7844/R7844 Service S1 2 1 2: SEM I-REGU LATED LOW-VOL TAG E VOLTAGES TO L I N E R ECT I f i E RS L I N E I NPUT START LOW-V O LTAGE INVE RTE R...
  • Page 82 Theory of Operation-7844/R7844 Service Inverter The Inverter operates on the low side of the resonant frequency of L1 237 and C1 237, which is approximately The Inverter stage converts the dc output of the Line 29 kHz. Pre-regulation is achieved by varying the hold-off I nput stage to a sine-wave current to drive Power Trans­...
  • Page 83 (' 0 ' Theory of Operation-7844/R7844 Service ",230 C R 1234 � C 1 237 01234 �> U N R E G U LAT E D ( A ) I N PUT V O LTAGE 01241 C R 1241 I t (S)
  • Page 86 Theory of Operation-7844/R7844 Service S E M I - R E G U LA T E D R 1 428 -54 V O LTS S E M I - R E G U LA T E D -50-VOLT +54 VOLTS...
  • Page 87 Theory of Operation-7844/R7844 Service in an opposite change at the collector of 01 4368 and at the tween ground and the - 50 V Sense voltage. The divider base of 01 451 . This change is connected to the + 1 5 V...

  • Page 88: Enhancer (Option 22)

    Theory of Clperation-7844/R7844 Service � Enhancement Level Enhancer (Option 22) The 20 ms gate from pin 1 of U41 1 5 turns 041 1 2 off and The Enhancer circuit effectively increases the writing rate 041 24 on. Then, Enhancer Preset adjustment R935 con­...

  • Page 90: Performance Check

    PERFORM A NCE CHECK This procedure is to be used for the 7844/R7844 as a check of instrument performance. Completion of each step in the procedure ensures that the instrument is correctly operating within all given tolerances. Refer to the following discussion for instructions on complete or partial performance checks.

  • Page 91: Signal Connections

    0.5 to 4 V ; amplitude accuracy, constant within 1 % of refer­ ence as output frequency changes. TEKTRONIX 7 A 1 9 Amplifier unit. Used throu9hout procedure Amplifier unit TEKTRONIX 7 A-Series (500 to provide vertical input to the M H z bandwidth required for instrument being checked.
  • Page 92 Tektronix Part No. 1 03-0030-00. T connector bnc-to-bnc operation check. 50 n; accuracy, Output termination for signal Tektronix Part No. 01 1 -0049-01 . Termination Impedance, generators, if amplifier is not within 2%; connectors, bnc. 50 n input impedance. Cable (2 required) Impedance, 50...
  • Page 93 Performance Check-7844/R7844 Service Table 4-2 PERFORMANCE CHECK SUMMARY Performance Check Characteristic Performance Requirement Procedure Title Deflection Factor Compatible with all 7000-Series plug-in F1 . Check Beam 1 and Beam 2 Vertical units. Amplifier Gain. (Option 21 only). Accuracy 1 % or less difference between vertical F2.
  • Page 95 Performance Check-7844/R7844 Service Table 4-2 (cont) Performance Check Performance Requirement Procedure Title Characteristic CALI BRATOR Risetime, Check CALI BRATOR Waveshape Square wave Falltime, and Duty Cycle. Positive going with baseline near ground. Polarity Output Voltage CALIBRATOR Output B1 . Check Into 1 00 kr! or greater 4 mV, 40 mV, 0.4 V, 4 V...
  • Page 96 Performance Check-7844/R7844 Service Table 4-2 (cont) Performance Check Procedure Title Performance Requirement Characteristic A GATE B5. Check A GATE MAIN/OLY'D Output Main of OLY'd gates from time-base unit Source Signals. installed in the A HORIZ compartment. MAIN OLY ' O Output Voltage Substantiated at the factory.

  • Page 97: Perf O Rmance Check Procedure

    PERFORM ANCE CH ECK PROCEDURE Introduction Page The following procedure checks the 7844/R7844 to meet B. CALI BRATOR AND OUTPUT SIGNALS the performance requirements given in Table 4-2. 1 . Check CALIBRATOR Output Voltage ..4-1 3 2.

  • Page 98: Setup Procedure

    5. Check Beam 1 and Beam 2 Vertical Amplifier Titles for external controls of the 7844/R7844 are cap­ 400 MHz Gain ......4-25 italized in this procedure (e.g.,...

  • Page 99: Z-Axis And Crt Display

    Time-mark generator Medium-frequency signal generator Mainframe standardizer calibration fixture Control Settings Set the 7844/R7844 front-panel controls as follows: e. CHECK-Graticule illumination occurs only after the beam 2 horizontal system has completed a sweep (adjust POWER switch GRAT I LLUM PR ESET, if necessary).

  • Page 100: Check Beam 1 Focus Range

    Performance Check-7844/R7844 Service c. Set the BEAM 2 FOCUS control for a well-defined Check BEAM 1 Focus Range display. a. Move time-base unit HORIZ compartment. d. CH ECK-Position the 0.5 div display to the top and then to the bottom graticule divisions and check for a well­...

  • Page 101: Check External Beam 2 Z-Axis Operation

    Performance Check-7844/R7844 Service g . Set the BEAM 2 I NTENSITY control for the brightest d. Set the time-base unit variable time/division control to obtain 1 marker for each major graticule division. trace without defocusing. e. Set the time-mark generator for 0 . 1 ms.

  • Page 102: Calibrator And Output Signals

    (use a bnc T connector). Connect the 7844/R7844 4 V CALIBRATOR signal to the other verti­ d. Set the test oscilloscope for a stable display, internal­...

  • Page 103: Check A And Bsawtooth Output Signals

    Performance Check-7844/R7844 Service h. Set the test oscilloscope triggering for auto mode with b. Set the rear-panel A GATE MAIN/DLY'D selector ac coupling from the internal source at a sweep rate of switch to MAIN. 0.1 ms/div. Set the triggering control so that the display starts at the 50% point on the rising edge of the waveform.

  • Page 104: Trigger Selection

    Calibration fixture signal standardizer h. Move time-base unit HORIZ Control Settings compartment. Set the 7844/R7844 front-panel controls as follows: LEFT A TRIG SOURCE i. Set BEAM 1 and BEAM 2 HORIZONTAL MODE B TRIG SOURCE RIGHT switches to B. BEAM 1...

  • Page 105: Check Trigger Gain

    Install the plug-in extender in the A HORIZ compart­ oscilloscope ; ± 10% (0.6 div). ment of the 7844/R7844 and set A TRIG SOURCE to LEFT. g. CH ECK-Dc level remains within 50 mV of ground reference (± 1 div). 4. Check Trigger Response h.

  • Page 106: Check Triggering Bandwidth

    Performance Check-7844/R7844 Service h . On the sampling unit, set the DELAY I NG Sweep to CH 1 I NT 10 /ls/div, the DELAYED Sweep to 1 ns, and the SWP con­ S LOPE trol to DELAYED (OUT). AUTO TRIG...

  • Page 107: Horizontal System (For Instruments 7844 Sn B1 1 Dodo-Above; R7844 Sn B1 00000-Above)

    Performance Check-7844/R7844 Service D. HORIZONTAL SYSTEM (For instruments 7844 SN B OOOO-above; R7844 SN B OOOOO-above) EquipmE!nt Required Calibration fixture signal standardizer Dc voltmeter Amplifier plug-in 42-inch, 50 Q cable with bnc connectors (two required) Time-base plug-in unit Time-mark generator...

  • Page 108: Check Beam 1 High-Frequency Timing

    Performance Check-7844/R7844 Service k. CHECK-High-frequency timing over the center 8 div d. Move the time-base unit to the RIGHT VER T compartment. within 0 . 3;2 div (4%). Set the time-mark generator for 2 ns markers and the e. Set BEAM 1 I N TENSITY control fully counterclock­...
  • Page 109 Performance Check-7844/R7844 Service k. CH ECK-H igh-frequency timing over the center 8 d iv n. CHECK-H igh-frequency timing over the center 8 div (one cycle every two divisions) within 0.32 div (4%). within 0.32 div (4%). o. Disconnect all cables.

  • Page 110: Check Beam 1 And Beam 2 Horizontal Amplifier Low-Frequency Linearity

    Performance Check-7844/R7844 Service E. HORIZON TAL SYSTEM (For instruments 7844 SN B 1 09999-below; R7844 SN B099999-below) Equipment Required Calibration fixture signal standardizer 18-inch. 50 Q cable with bnc connectors Amplifier plug-in unit 18-inch cable with bsm female and bnc male connectors Time-base plug-in unit TimE�-mark generator...

  • Page 111: Check Beam 1 High-Frequency Timing

    Performanc:e Check-7844/R7844 Service e. Set the BEA 1 I NTEN SITY control fully counter­ j. CHECK-Refer to the time-base unit instruction man­ ual for performance check or calibration procedures for clockwise and BEA 2 I NTENSITY control for a usable display.

  • Page 112: Vertical System

    H igh-frequency signal generator Amplifier plug-in unit Calibration fixture signal standardizer ContrOl Settings f. Move the calibration fixture to the RIGHT VERT compartment. Set the 7844/R7844 front-panel controls as follows: CALI BRATOR (1 kHz) 4 V (push button in) g. Move time-base unit...

  • Page 113: Check Low-Frequency Linearity

    Performal n ce Check-7844/R7844 Service g. Position the display with the VERT SEP (1) control to d. CHECK-Vertically position the display and check for align the bright center trace with the center horizontal less than 0.1 div of compression or expansion within the graticule l ine.

  • Page 114: Check Beam 1 And Beam 2 Vertical Amplifier

    Performance Check-7844/R7844 Service 5. Check BEAM 1 and BEAM 2 Vertical Amplifier m. Move the calibration fixture to the RIGHT VERT com­ 400 MHz Gain partment and the time-base unit to A HORIZ compartment. a. Insert the calibration fixture in the RIGHT VERT com­...

  • Page 115: Check Vertical Trace Separation Operation

    Performanc:e Check-7844/R7844 Service o. CHECK-Crt display for 0 .08 div or less of 150 MHz i. Move amplifier unit LEFT VERT compartment. signal (verifies beam 1 channel isolation at least 100: 1 from dc to 150 M Hz). j. Set the high-frequency generator for 8 div of deflection at 1 50 M H z.

  • Page 116: Readout System

    Time-base plug-in unit Control Settings c. CH ECK-Set the time-base unit for several sweep rates throughout its range. Check that the readout charac­ Set thl� 7844/R7844 front-panel controls as follows: ters are presented independent of the sweep. READOU T EXTERNAL-BEAM 2 d.
  • Page 117 To maintain instrument accuracy, check the adjustment zontal timing with 7000-Series real-time plug-in units and of the 7844/R7844 every 1000 hours of operation, or every the 7844/R7844 calibrator signal. six months if used infrequently. Before complete adjust­...
  • Page 118 Applicable Test Equipment Description Minimum Specifications Usage Range, - 7S to + 1S0 Calibrator output accuracy a. TEKTRONIX DM S01 A Digital Precision de voltmeter Multimeter. a check and adjustment. Power volts; accuracy, within 0.2%. supply voltages, check and adjustment. Z-Axis and Dis- play check and adjustment.
  • Page 119 P6053B Probe. an inverting input and both added and alternate verti- cal modes. b. TEKTRONIX 475 Oscillo- scope with P6053B Probe. c. Refer to the Tektronix Cats log for compatible oscilloscope system. T connector bnc-to-bnc External Z-axis operation Tektronix Part No. 1 03-0030-0 check.
  • Page 120 Applicable Test Equipment Des cription Minimum Specifications Usage Output termination for signal Tektronix Part No. 01 1 -0049-01 . Termination Impedance, 50 Q; accura- cy, within 2%; connectors, generators, if amplifier is not 50 Q input impedance. Impedance, 50 Q; type, U sed throughout procedure Tektronix Part No.
  • Page 121 Adjustment Procedure-7844/R7844 Service Table 5-2 ADJUST MENT SUMMARY Adjustment Procedure Title Performance Requirement Characteristic VERTICAL Compatible with all 700D-Series plug-in units. G3. Adjust Beam 1 and Beam 2 Deflection Factor Vertical Amplifier Gain. (Option 21 only.) G4. Check Beam 1 and Beam 2...
  • Page 122 Adjustmenli Procedure-7844/R7844 Service Table 5-2 (cont) Adjustment Procedure T itle Characteristic Performance Requirement HORIZONTAL (cont) Horizontal Display Modes Plug-in compartment controlling horizontal Does not normally require customer deflection of electron beam. verification; substantiated at the factory. · BEAM 1 BEAM 2 Phase Shift Between Vertical and Hori­...

  • Page 123: Connect The Instrument To A Power Source Tha Meets

    ........5-1 6 Setup Procedure 1 7 A. Adjust Beam 1 and Beam 2 CRT Centering 1 . Remove the side and bottom covers from the 7844 or (R498E:, R5988) (For...

  • Page 124: Allow At Least 20 Minutes Warmup Before Proceeding

    3. Allow at least 20 minutes warmup before proceeding. NOTE Titles for , g xternal controls of the 7844/R 7844 are cap­ italized in this procedure (e.g., B TRIG SOURCE ). In­ ternal ad justments are initial capitalized (e.g., Beam 2 Horiz Gain).
  • Page 125 Ex­ pose the 7844 Power Supply adjustments and test pOints by removing the power unit from the rear of the 7844 3. CHECK REMAINING POWER·SUPPLY (interconnecting cables remain connected). See the Mainte­...
  • Page 126 Adjustmentt Procedure-7844/R7844 Service e. Install the power unit and connect the line cord. tolerance. Connect meter common lead to TP Gnd Sens (see Fig. 9-27). b. INTERACTION-If the power supplies are not within Table 5-3 the tolerances given in Table 5- 3 , repeat steps A 1 , Adjust POWER SUPPLY TOLERANCE - 50 Volt Power Supply and A2, Adjust Inverter Control.
  • Page 127 Connect a 1 0X probe to the input of the test oscillo­ scope and set the input coupling to ac. Check the probe d. Check-Total pulse signal amplitude (displayed on compensation using the 7844 CALIBRATOR signal . the test oscilloscope) must be at least 64 V. 5-11...

  • Page 128: Switch (Option 21 Only)

    (see Fig. 9- 3 0). For easy access to TP2086 and the Beam 2 Z-Axis c. Set the 7844/R7844 HORIZONTAL MODE to: adjustments, remove the power unit (on the R7844, Beam 2 BEAM ·1...

  • Page 129: Below

    Set the Beam 2 I NTENSITY fully counterclockwise ADJU:ST BEAM 1 AND BEAM 2 SYMMETRY and set a base line reference on the test oscilloscope. & (R 1 838 a nd R2838) (7844 SN B 1 09999 Below; & R7844 SN B099999 Below only) e.
  • Page 130 Adjustment Procedure-7844/R7844 Service 8. ADJUST BEAM 2 FOCUS RANGE (R2436, R2576) b . Set the Signal Standardizer Test switch to Vert or Horiz + Step Resp and the Rep Rate switch to 1 MHz. a. Set tl1e time-base unit sweep rate for 1 ms/div.
  • Page 131 Adjustment Procedure-7844/R7844 Service 1 1 . ADJUST BEAM 2 EDGE FOCUS (R2576, R2552) I. Check-Repeat parts b through d. a. Move the Calibration Fixture Signal Standardizer to the RIGHT VERT compartment and the time-base unit to m . Replace the Calibration Fixture Signal Standardizer, the B HORIZ compartment.

  • Page 132: Sn B1 1 0000-Above; R7844 Sn B1 00000

    Set the time-mark generator for 1 ms markers. 1 5. ADJUST BEAM 1 GEOMETRY (R2568, R 1 985, R 1 976, R2!;60) (R4985, R4976 For instruments 7844 SN B 1 1 0000-above; R7844 SN B 1 00000-above) c. Set the amplifier unit deflection factor and position a.

  • Page 133: Sn B1 09999-Below; R7844 Sn B099999

    1 7B. ADJUST BEAM 1 AND BEAM 2 CRT source. CENTERING (R 1 988, R2988) (For instruments 7844 SN B 1 09999-below; R7844 SN B099999-below) a. Move the time-base unit to the LEFT VERT compart­...
  • Page 134 Adjustment Procedure-7844/R7844 Service d. Check-Vertical trace must be within 0.1 div of the Remove the jumper wire. beam 1 recommended setting noted on the crt centering data label (label located on crt shield). 1 8. ADJUST Y-AXIS ALIGNMENT (R386) e. ADJUST -Beam 1 Crt Ctr adjustment R 1 988 to align the vertical trace with the recommended setting indicated on a.
  • Page 135 1 . ADJU ST CALIBRATOR OUTPUT VOLTAGE nel of the test oscilloscope (use a bnc T connector). Connect (R9 1 5) the 7844/R7844 4 V CALIBRATOR signal to the other verti­ cal channel. a. Set both the 4 V and 0.4 V CALI BRATOR push but­...
  • Page 136 BEAM FINDER Push button out HOF: IZONTAL MODE f. Set the 7844/R7844 A TRIG SOURCE to LEFT. g. Using the POSITION and AMPLITUDE controls of the ADJUST TRIGGER RESPONSE signal standardizer and the TRIGGER ING LEVEL and SCAN controls of the sampling unit, set up a stable, 6 div display on the test oscilloscope.
  • Page 137 Adjustment Procedure-7844/R7844 Service t. Move the signal standardizer to the LEFT VERT o. ADJ UST -R546 for aberrations of � 1 5% (0.9 div). compartment. p. Move the plug-in extender to the HORIZ compartment. u. Set B TRIG SOURCE to LEFT.
  • Page 138 Adjustment Procedure-7844/R7844 Service E. HORIZONTAL SYSTEM (For instruments 7844 SN B 1 1 0000-above; R7844 SN B 1 00000-above) Equipment Required Calibration fixture signal standardizer Dc voltmeter Amplifier plug-in unit 42-inch, 50 cable (two required) with bnc connectors Three-inch screwdriver...
  • Page 139 Adjustment Procedure-7844/R7844 Service 2. ADJ UST BEAM 1 HORIZONTAL AMPLIFIER f. Set B TRIG SOURCE to LEFT and the time-base unit triggering controls for a stable display. GAIN (B4820) a. Install the calibration fixture in the B HORIZ compart­ ment and set the BEAM 1 HOR IZONTAL MODE switch g.
  • Page 140 Adjustment Procedure-7844/R7844 Service 4. ADJUST BEAM 2 HORIZONTAL CENTERING Check-One trace per graticule division within 0.08 div over the center 8 vertical graticule divisions. (R5840, R:58 1 6) a. Install a time-base unit in the RIGHT VERT compart­ ment. Install the calibration fixture in the A HORIZ g.
  • Page 141 Adjustment Procedure-7844/R7844 Service o. Check-High-frequency timing over the center 8 div j . Set the time-base triggering controls for a stable display. (one cycle every two divisions) within 0.32 div (4%). k. Check-High-Frequency timing over the center 8 div within 0 . .32 div (4%).
  • Page 142 Adjustment Procedure-7844/R7844 Service F. HORIZONTAL SYSTEM (For instruments 7844 SN B 1 09999-below; R7844 SN B099999-below) Equipment Required Calibration Fixture Signal 1 8-inch, 50 cable with bnc connectors Standardizer Amplifier plug-in unit Three-inch screwdriver Time-base plug-in unit 1 8-inch cable with bsm female and bnc male connectors...
  • Page 143 Adjustment Procedure-7844/R7844 Service p. ADJU ST -Beam 1 Horiz Gain R 1 81 6 for 1 div be­ k. Disconnect the time-mark generator and remove the tween each of the 9 displayed traces (see Fig. 9-36). amplifier unit. q. INTERACTION-Significant adjustment of the Beam I.
  • Page 144 Table 5-4 to the amplifier unit. HOmZONTAL SYSTEM HIGH-FREQUENCY COMPENSAT ION (Fol' instruments 7844 SN B 1 09999-belowj f. Set the B TRIG SOURCE switch to RIGHT and the R7844 SN B09999-below) time-base unit triggering controls for a stable display.
  • Page 145 Adjustment Procedure-7844/R7844 Service r. ChElck-High frequency timing. Repeat part i. s. INTERACTION-If the high-frequency timing param­ eters cannot be met, repeat parts j through p. t. Remove all test equipment. 5-29 REV JUN 1 ' 9 81...
  • Page 146 Adjustment Procedure-7844/R7844 Service G. VER TICAL SYSTEM Equipment Required Time-base plug-in unit Low-capacitance screwdriver Amplifier plug-in unit bnc female to dual clip leads Calibration fixture signal standardizer nylon tuning tool Hi!�h-frequency signal generator Three-inch screwdriver ADJUSTMENT LOCATIONS 5 BEFORE YOU BEGIN, see in the Diagrams section.
  • Page 147 Adjustment Procedure-7844/R7844 Service Check-One trace graticule division within g. CH ECK-(delete with Option 2 1 ) Trace remains with­ 0.01 div over the center 6 horizontal graticule divisions. in 0.5 div of the center horizontal graticule line while switch­ ing the BEAM 2 V ERTICAL MODE switch from RIGHT to LEFT.
  • Page 148 Remove the CALIB RATOR signal. q. Move time-base unit HORIZ compartment. NOTE (Effective Serial Number B050000-up; 7844) (Effective Serial Number B040000-up; R7844) Refer r. Position the display with the VERT SEP (1 ) control to Recalibration After Repair in the Maintenance section align the bright center trace with the center horizontal for an input compensation ad justment procedure.
  • Page 149 Adjustment Procedure-7844/R7844 Service 7. ADJUST BEAM 2 VERTICAL HIGH-FREQUENCY e. ADJ U ST -LF Camp 1 adjustment R 1 749 and LF Camp 2 adjustment R 1 764 for flat top within 0.06 div (see COMPENSATION (R2764, R2749, R2743, R2758, Fig.
  • Page 150 Adjustment Procedure-7844/R7844 Service Table 5·6 BEAM HIGH· FREQUENCY COMPENSATION Primary Area of Best Sweep Adjustment Pulse Affected Rate R2743 First 1 00 ns 1 0 ns/div R2758 L2667 First 2 ns 2 ns/div C2658 2 ns/div R2658 First 5 ns...
  • Page 151 Three-inch screwdriver in the Diagrams section. BEFORE YOU BEGIN, see ADJUSTM E N T LOCATI ON S Control Settings Set the 7844/R7844 front-panel controls as follows: R EADOUT B EA M 2 GAT E D EXTERNAL-BEAM 2 GAT E D...
  • Page 152 50 mv/div. tion. Release the amplifier unit trace-identify button. b. Set the time-base unit triggering for a free-running trace at 1 rns/div. This completes the 7844/R7844 Adjustment procedure. 5-36 REV JUN 1 981...
  • Page 153 7844/R7844. breakdown and will improve the reliability of this instrument. The severity of the environment to which the 7844/R7844 is sut)jected determines the frequency of maintenance. A con­ Panel RE!mOval venient time to perform preventive maintenance is preceding recalibration of the instrument.
  • Page 155 7844/R7844, check that the equipment used with this in­ strument is operating correctly. Check that the signal is Description: 1 0 MQ input impedance and 0 to 500 volts properly connected and that the interconnecting cables are range, ac and dc;...

  • Page 156: Trig Source )

    C I R C U I T ISOLAT I ON T R O U B L ESHOOT I N G C H A R T � S· Connect the 7844/R7844 to correct power source. Turn POW E R ON. Set �...
  • Page 157 Check readout display with all Check Readout Logic correct - combinations of the 7844/R7844 on Mode Switch board mode switches < '­ Check readout display for Operating correctly all plug-in switch combinations Set R EADOUT INTENSITY to the clockwise detent position. Check that one frame of read-...
  • Page 158 (0.1 % accuracy), and correct ripple with a test oscilloscope. Vary the autotransformer throughout the regu­ Disconnect the power source before removing or re­ lating range of the 7844/R7844 and check that it is within placing semiconductors. the power supply tolerances given in Table 6-1 . The voltages in Table 6-1 are measured between the power sup­...
  • Page 159 Inc. to satisfy particular requirements, or are manufactured need to bH replaced unless the measured value varies wide­ for Tektronix, Inc. to our specifications. Most of the me­ ly from th3 specified value. chanical parts used in this instrument have been manufac­...
  • Page 160 6-2. Fig. Power unit securing screws. 7844/R7844 to gain better access to the Logic board, Beam 2 Z-Axis board (7844 only), Low-Voltage board, or for pow­ er-unit maintenance. To remove the power unit, first remove W A R N I N G the four screws that hold the power unit to the rear frame of the instrument (see Fig.
  • Page 161 Maintenance-7844/R7844 Service Remove and replace chas­ 1 . Slid out the power unit as described previously. Chassis-Mounted Boards. sis-mounted boards as follows. 2. Disconnect the crt anode plug from the jack located at the front of the power unit. Ground this lead to the chassis 1 .
  • Page 162 Maintenan(:e-7844/R7844 Service 1 . Slide out the power-unit as described previously. The Signals Out board i s part A-25 Signals Out Board. of a subassembly. Remove and replace the Signals Out board as follows. 2. Disconnect the pin connectors from the Main Inter­...
  • Page 163 Maintenance-7844/R7844 Service 1 1 . Replace the power unit in the instrument. 7. Apply silicone grease to the base of the Output IC. Insert the IC into its socket with the pin alignment tab orient­ ed as previously noted. To remove and re­...
  • Page 164 Maintenan(:e-7844/R7844 Service 2. Remove the power unit from the instrument as de­ Cap-Rectifier board, away from A27, Power Supply Inverter scribed under Power Unit. board, until the interconnecting pins are cleared . Remove A28, Cap-Rectifier board , and the high-voltage supply box as a unit.
  • Page 165 Maintenance-7844/R7844 Service 27. Place the power-unit ground lead and power-switch A28-Cap-Rectifier Board. Remove and replace the Cap­ cable in the slot in the top of A28, Cap-Rectifier board. Rectifier circuit board as follows. 28. Mount the capacitors with the capacitor bracket to 1 .
  • Page 166 7844/R7844. The Follower board is held in place by a follower spring so the board can 4. Remove the board from the instrument and discon­...
  • Page 167 A circuit-board pin replacement kit Circuit-Board Pins. Replace silicone grease when replacing these including necessary tools, instructions, and replacement transistors. pins is available from Tektronix , Inc. Order Tektronix Part 6- 1 5 REV J U N 1 981...
  • Page 168 Remove and replace the cathode­ multi-layer boards is not recommended; refer such repairs ray tube as follows. to your local Tektronix Field Office or representative. W A R N I N G To replace a pin mounted on a circuit board, first discon­...
  • Page 169 Push Button Switches on the crt base with the other. As the crt starts out of the The push button switches used on the 7844/R7844 are shield, grasp it firmly. Guide the anode lead through the circuit board mounted. Remove the associated circuit board cutout in the crt shield as the crt is removed.
  • Page 170 Power Transformer Replace the power transformer only with a direct re­ After any electrical component has been replaced, the placement Tektronix transformer. Remove and replace the calibration of that particular circuit should be checked, as power transformer as follows: well as the calibration of other closely related circuits. Since the low-voltage supplies affect all circuits, calibration of the 1 .

  • Page 171: Circuit

    P2493 See Fig . 9-31 Pin 8 Note: Adjustment Circuit Numbers in parentheses are for instruments 7844 SN B 1 1 0000-above; R7844 SN B 1 00000-above. Vertical Input Compensation Adjustments Adjust Vertical Input Compensation (R3720, C3720, R3620, R3665, C3665, R3765, and C3765)
  • Page 172 7. Move the Calibration Fixture Signal Standardizer to Instrument Repackaging the LEFT VERT compartment. If the Tektronix instrument is to be shipped to a Tektronix Service Center for service or repair, attach a tag showing: owner (with address) and the name of an individ­...
  • Page 173 Conversion kits, for most options, are available and can OPTION 22 be installed at a later time. For further information on instru­ ment options, see your Tektronix Catalog or contract your This option provides an oscilloscope enhancer to effec­ Tektronix Field Office.
  • Page 174 Instrument Options-7844/R7844 Service Table 7- 1 (cont) Instrument Option Manual Section Location of Information Electrical Specification Vertical specifications in Table 1 -1 include characteristics unique to Option 21 . Features Operating Includes Option 21 features. Information Controls and Connectors Figure 2-1 includes controls and connectors information unique to Option 2 1 .
  • Page 175 Instrument Options-7844/R7844 Service Table 7- 1 (cont) Location of Information Instrument Option Manual Section Instrument Options Option 21 Introductory page contains a description of the (Dedicated Vertical Instrument Dedicated Vertical system (Option 2 1 ). System) Options Replaceable Replaceable parts unique to Option 21 contain the footnote Electrical "...
  • Page 176 P U LSED mode. The major controls required for the operation of the 7844/R7844 Option 22 (Writing Speed Enhancer) are locat­ ENHANCER PRESET Adjustment (PULSED Mode) ed on the front panel of the instrument. However, the...
  • Page 177 THE R E ADOUT CI R C U I T BOA R D I S LOCA­ TED ON T H E R I GH T S I D E OF THE 7844 AND IN THE TOP R I GHT C E NT E R OF T H E R7844.
  • Page 178 Instrument Options-7844/R7844 Service CHECK ENHANCER OPERATION e. Set the time-base unit sweep rate tor 0. 1 s/div. a. Install a time-base unit in the B HORIZ compartment. f. CHECK-The entire crt phosphor is illuminated after b. Set the time-base unit sweep rate for 1 ms/div and the sweep has ended and not illuminated during the sweep.
  • Page 179 E L E CT R I CA L PARTS PARTS O R D E R I N G I N F O R MATI O N Replacement parts are available from or through you r local Tektronix, I nc. Field Office or representative.
  • Page 180 Replaceable Electrical Parts-7844/R7844 Service C ROSS I N D EX- M F R . CODE N U M B E R TO M A N U FACTU R E R C ity, State, Zip Mfr. Code M a n ufacturer...
  • Page 181 Replaceable Electrical Parts-7844/R7844 Service CROSS I N D EX- M F R . CODE N U M B E R TO MAN U FACT U R E R Mfr. Code M an ufacturer Address C i ty, State, Z i p 7 84 8 8 STACKPOLE CARBON CO .
  • Page 183 CKT BOARD ASSY : HORI ZONTAL AMPLI F IER( BEAM 2 ) 80009 6 70-2 7 6 7 - 0 1 ----- ---- ( R 7844 ONLY ) 6 70-2 7 6 7-02 B 1 30636 CKT BOARD ASSY : HORI ZONTAL AMPL IFIER( BEAM 2 ) 80009...
  • Page 184 CKT BOARD ASSY : CAP-REC T I F I E R 80009 6 7 0- 1 6 1 9 - 1 9 - ----- ( R 7844 ONLY ) 6 7 0- 1 6 1 2- 2 2 B 1 4 1 1 90 CKT BOARD ASSY : CAP-RECT IFIER...
  • Page 186 CAP . , FXD , CER D I : 4 70PF , 5% , 500V 7 2 9 8 2 0 8 3 1 08 5 Z5EOO4 7 1 J ( R 7844 OPTION 2 1 ONLY ) - - - - - - 8·8...
  • Page 187 CAP . , FXD , CE R D I : S . 6PF , S% , 200V 7 2 9 8 2 8 1 1 1 B200COGS69C ----- -- ( 7844 OPTION 2 1 ONLY ) ----- - ( NOMINAL VALUE , SELECTED ) C 6 1 8...
  • Page 188 CAP . , FXD , CER D I : 1 PF , 10% , 50V 72982 8 1 0 1 B0 5 7 COK0 1 0 9 B ----- ----- ( R 7844 OPTION 2 1 ONLY ) C 7 2 2 2 8 3-01 58-00 B 0 1 0 1 00 B l l 0 7 94X CAP .
  • Page 189 Replaceable Electrical Parts-7844/R7844 Service M f r Tektr o n i x Serial / Mo d e l N o . & M f r Part Number C kt N o . P a r t N o . Dscont...
  • Page 191 56289 1 9 6D1 04x0050HAl CAP . , FXD , ELCTLT : 0 . IUF , 20% , 50V ----- ----- ( R 7844 ONLY ) C 1 3 7 1 290-0580-00 8090320 CAP . , FXD , ELCTLT : 0 . 2 7 UF , 20% , 50V...
  • Page 192 CAP . , FXD , CE R D I : 2 . 5 PF , 5% , 50V 72982 8 1 0 1 B0 5 7 COK0295B ---- ( NOMINAL VALUE , SELECTED 7844 ONLY) C l 7 3 6 2 8 3-0 1 58-00 B 1 42 3 3 0 CAP .
  • Page 193 B099999X CAP . , FXD , C E R D I : 0 . 00 I UF , + 1 00-0% , 500V -- ----- ( R 7844 ONLY ) C I 82 2 28 3-0000-00 BOI O I OO...
  • Page 195 Replaceable Electrical Parts--7844/R7844 Service M f r Te ktron i x Seri a l / M o d e l N o . & Code M f r Part N u m ber Ckt N o . Part N o .
  • Page 196 Replaceable Electrical Parts-7844/R7844 Service M f r Tektro n i x Seri a l / M o d e l N o . & M f r Part N u m ber Name Description Code Ckt N o . Part N o .
  • Page 198 Replaceable Electrical Parts-7844/R7844 Service Tektro n i x S e r i a l / Mo d e l N o . & Code Mfr Part N u mber Ckt N o . Part N o . Dscont N a m e...
  • Page 199 Replaceable Electrical Parts-7844/R7844 Service Seri a l ! M o d e l N o . Tektron i x & Mfr Part N u mber Code Dscont N a m e Description Ckt N o . Part N o .
  • Page 200 7 2 9 8 2 8 1 0 1 B0 5 7COK0 1 0 9 B ( C 3 60 1 , 7844 / R 7 844 ONLY ) C3605 2 8 3-02 5 1 -0 0 8 1 2 1 B 14 5COG0 870J CAP .

This manual is also suitable for:

R7844

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