Tektronix WFM91 manual

Service Manual WFM 90 and WFM 91 Handheld W aveform, V ector , Pictur e, and Audio Monitor 070-8969-04 This document supports firmware version 1.00 and above. W arning The servicing instructions are for use by qualified personnel only . T o avoid personal injury , do not perform any servicing unless you are qualified to do so. Refer to all safety s[...]

Copyright © T ektronix, Inc. All rights reserved. T ektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supercedes that in all previously published material. Specifications and price change privileges reserved. Printed in the U.S.A. T ektronix, Inc., P .O. Box 1000, W ilsonville, OR 97070?[...]

W ARRANTY T ektronix warrants that the products that it manufactures and sells will be free from defects in materials and workmanship for a period of one (1) year from the date of shipment. If a product proves defective during this warranty period, T ektronix, at its option, either will repair the defective product without charge for parts and labo[...]

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Service Assurance If you have not already purchased Service Assurance for this product, you may do so at any time during the product’ s warranty period. Service Assurance provides Repair Protection and Calibration Services to meet your needs. Repair Protection extends priority repair services beyond the product’ s warranty period; you may purch[...]

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WFM 90 and WFM 91 Service Manual i T able of Contents General Safety Summary vii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Service Safety Summary xi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preface xiii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [...]

T able of Contents ii WFM 90 and WFM 91 Service Manual Fault Symptom T able 6–35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T roubleshooting Flowcharts 6–36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Connector Diagram 6–50 . . . . . . . . . . . . . . . . .[...]

T able of Contents WFM 90 and WFM 91 Service Manual iii List of Figures Figure 2–1: Installing the viewing hood 2–2 . . . . . . . . . . . . . . . . . . . . . . . . Figure 2–2: Installing the desk stand 2–2 . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 2–3: Instrument fr ont panel 2–4 . . . . . . . . . . . . . . . . . . . [...]

T able of Contents iv WFM 90 and WFM 91 Service Manual Figure 6–23: Flowchart for all white display 6–43 . . . . . . . . . . . . . . . . . . . . Figure 6–24: Flowchart for untrigger ed waveform display 6–44 . . . . . . . . Figure 6–25: Flowchart for unlocked vector display 6–45 . . . . . . . . . . . . . . Figure 6–26: Flowchart for ve[...]

T able of Contents WFM 90 and WFM 91 Service Manual v List of T ables T able 1–1: V ertical deflection system 1–6 . . . . . . . . . . . . . . . . . . . . . . . . . . T able 1–2: DC restoration 1–7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T able 1–3: Audio mode 1–7 . . . . . . . . . . . . . . . . . . . . . . [...]

T able of Contents vi WFM 90 and WFM 91 Service Manual[...]

WFM 90 & WFM 91 Service Manual vii General Safety Summary Review the following safety precautions to avoid injury and prevent damage to this product or any products connected to it. Only qualified personnel should perform service pr ocedur es. T o avoid potential hazards, use this product only as specified. T o A void Fire or Shock Hazards: Use[...]

General Safety Summary viii WFM 90 & WFM 91 Service Manual For information on replacing and recharging batteries specific to this product, refer to the detailed instructions provided in this manual. Replace Batteries Properly . Before replacing batteries, turn the instrument of f and disconnect the AC adapter . Use only the size and type of bat[...]

General Safety Summary WFM 90 & WFM 91 Service Manual ix T erms in this Manual. These terms may appear in this manual: W ARNING. W arning statements identify conditions or practices that could r esult in injury or loss of life. CAUTION. Caution statements identify conditions or practices that could r esult in damage to this pr oduct or other pr[...]

General Safety Summary x WFM 90 & WFM 91 Service Manual[...]

WFM 90 & WFM 91 Service Manual xi Service Safety Summary Only qualified personnel should perform service procedures. Read this Service Safety Summary and the General Safety Summary before performing any service procedures. Do Not Service Alone. Do not perform internal service or adjustments of this product unless another person capable of rende[...]

Service Safety Summary xii WFM 90 & WFM 91 Service Manual[...]

WFM 90 and WFM 91 Service Manual xiii Preface This manual provides instructions for servicing the WFM 90 and WFM 91 Handheld W aveform, V ector , Picture, and Audio Monitors. This manual describes features and specifications that are common to all generator modules. These include system configuration and the common control interface. About This Man[...]

Preface xiv WFM 90 and WFM 91 Service Manual[...]

WFM 90 and WFM 91 Service Manual xv Introduction Service Strategy NOTE . Thr oughout this manual, any field-r eplaceable component, assembly , or part of this oscilloscope is r eferr ed to generically as a module. This manual contains all the information needed for periodic maintenance of the WFM90 or WFM91 Handheld W aveform, V ector , Picture, an[...]

Introduction xvi WFM 90 and WFM 91 Service Manual The following services may be purchased to tailor repair and/or calibration of your WFM90 or WFM91 Handheld W aveform, V ector , Picture, and Audio Monitor to fit your requirements: Option M2. When you order option M2, you receive a five year warranty and remedial service agreement. Option M8. When [...]

Introduction WFM 90 and WFM 91 Service Manual xvii Module Repair and Return. This service returns to you within 10 days the same module that you shipped to T ektronix. The module shipped is repaired, tested, and returned to you from the Beaverton, Oregon service center . It is not updated to match current modules of the same type. Again, each modul[...]

Introduction xviii WFM 90 and WFM 91 Service Manual[...]

Specifications[...]

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WFM 90 and WFM 91 Service Manual 1–1 Specifications This section includes the following information: H Product description H Characteristics tables Refer to Performance Requir ements on page 1–5 for the conditions over which the characteristics listed in this section are valid. Product Description The T ektronix WFM 90 or WFM 91 Handheld W avef[...]

Specifications 1–2 WFM 90 and WFM 91 Service Manual The key features of this instrument are described below: Rasterized Color LCD Display . This instrument uses a color, four -inch diagonal, backlit, thin-film transistor (TFT) LCD raster display module. The proprietary rasterizer displays analog waveforms or vectors simultaneously with the approp[...]

Specifications WFM 90 and WFM 91 Service Manual 1–3 The video output will drive a remote monitor or video switcher . The audio signal is output through a mini-headphone stereo jack that outputs the mono input signal to both stereo channels. The audio volume is fixed for each reference level. The larger the displayed signal, the louder the volume.[...]

Specifications 1–4 WFM 90 and WFM 91 Service Manual W aveform-in-Picture Display Mode. The W aveform-in-Picture (WIP) display mode provides a 1/4-screen-sized window over the Picture display for any one of the W aveform, V ector , or Audio displays. The WIP window can be positioned to any one of the four corners of the display . The Arrow Buttons[...]

Specifications WFM 90 and WFM 91 Service Manual 1–5 Characteristics T ables The characteristics tables use the following abbreviations: Performance Requirement. All performance requirements in the characteristics tables are identified with Req and can be assured by performing the procedures in the Performance V erification section. Allow a warm-u[...]

Specifications 1–6 WFM 90 and WFM 91 Service Manual T able 1–1: V ertical deflection system Category Description Frequency Response REF: Specifications apply for full screen height video input signal with V ari- able Gain off. REQ: Flat Filter 1 V Full Scale: 50 kHz to 6 MHz within 2% of response at 50 kHz. REQ: Flat Filter X5 Gain: 50 kHz to 6[...]

Specifications WFM 90 and WFM 91 Service Manual 1–7 T able 1–1: V ertical deflection system (Cont.) Category Description DC Input Impedance (Unterminated) REQ:  15 k W . REF: With input switch in the HIZ position. Video Input Return Loss REF:  40 dB from 50 kHz to 6 MHz with 75 W termination on. Video Out Return Loss (75 W ) REF:  30 d[...]

Specifications 1–8 WFM 90 and WFM 91 Service Manual T able 1–4: Horizontal deflection system Category Description Sweep REQ: Sweep will occur in all horizontal mode settings with or without synchroniza- tion. REF: Sweep Length: T wo Line and Two Field sweep length is nominally 12 divisions. 1LINE Sweep Repetition Rate REQ: Equal to line rate of[...]

Specifications WFM 90 and WFM 91 Service Manual 1–9 T able 1–5: V ector mode (Cont.) Category Description Display Differential Phase REF:  1 ° . REF: Measured with 140 IRE (1 V) linearity signal (5 step, 10 step, or Ramp) with 40 IRE (300 mV) of subcarrier . Display Differential Gain REF:  1%. REF: Measured with 140 IRE (1 V) linearity s[...]

Specifications 1–10 WFM 90 and WFM 91 Service Manual T able 1–6: Synchronization Category Description Input Requirements REQ: Internal Reference: Composite video or black burst with sync amplitudes 40 IRE (300 mV P AL)  6 dB. REQ: External Reference: Sync amplitude between 143 mV and 4 V will synchro- nize sweeps. External Reference Input RE[...]

Specifications WFM 90 and WFM 91 Service Manual 1–1 1 T able 1–8: Environmental characteristics (Cont.) Category Description Vibration — Operating REF: 15 minutes each axis at 0.015 inch, frequency varied from 10 Hz to 55 Hz to 10 Hz in 1-minute cycles with instrument secured to vibration platform. T en minutes each axis at any resonant point[...]

Specifications 1–12 WFM 90 and WFM 91 Service Manual T able 1–10: Safety/EMI Category Description Certifications REQ: Designed to meet or exceed: ANSI/ISA S82 – Safety Standard for Electrical and Electronic T est, Measur- ing, Controlling, and Related Equipment. CAN/CSA C22.2 No. 1010.1-92 – Safety Requirements for Electrical Equip- ment fo[...]

Operating Information[...]

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WFM 90 and WFM 91 Service Manual 2–1 Operating Information This section contains the following information: H Mechanical and electrical installation instructions H Operating instructions that relate to the service of this instrument Installation Before installing the WFM 90 or WFM 91 Handheld W aveform, V ector, Picture, and Audio Monitor , refer[...]

Operating Information 2–2 WFM 90 and WFM 91 Service Manual Figure 2–1: Installing the viewing hood Desk Stand. The optional desk stand provides the user with a stable means to hold the instrument upright on a flat surface. The prongs of the stand are inserted into the holes in the back of the instrument as illustrated in Figure 2–2. Figure 2?[...]

Operating Information WFM 90 and WFM 91 Service Manual 2–3 Follow these instructions when physically installing this instrument: Power Source. This instrument is designed to operate from either six C-cell batteries, alkaline or rechargeable NiCad, or from an AC adapter wall unit producing 12 VDC. CAUTION. T o avoid possible damage to the instrume[...]

Operating Information 2–4 WFM 90 and WFM 91 Service Manual Operating Information This section will acquaint you with the basic principles of operating this instrument so that you can service it. Detailed operating instructions are located in the user manual. The instrument front panel is illustrated in Figure 2–3. Figure 2–3: Instrument front[...]

Operating Information WFM 90 and WFM 91 Service Manual 2–5 Power Switch. Press the ON button to toggle the instrument power on and off. The current instrument keypad and menu selections are saved when the instrument is turned off using this button. NOTE . The instrument configuration is not saved if the power sour ce is r emoved befor e the instr[...]

Operating Information 2–6 WFM 90 and WFM 91 Service Manual Arrow Buttons. The function of the Arrow Buttons is dependent on the current state of the instrument. For the W aveform and Audio display modes, they control signal positioning. For the V ector display mode, they control vector phase, with the Y and B buttons providing fine adjustment, an[...]

Operating Information WFM 90 and WFM 91 Service Manual 2–7 DC IN 11-18V Figure 2–4: Instrument side panels DC Input Power Connector . The DC IN power connector is a 2 mm plug which accepts a 12 VDC power input, ranging from +1 1 V to +18 V , using a negative center lead. CAUTION. T o avoid possible damage to the instrument cir cuitry when using[...]

Operating Information 2–8 WFM 90 and WFM 91 Service Manual The following special operating modes can be activated through the menus: Amplitude Alarm Mode. The Amplitude Alarm mode provides a means to automatically monitor the signal amplitude for the W aveform and Audio displays. This mode is enabled through the Configuration menu. For the W avef[...]

Operating Information WFM 90 and WFM 91 Service Manual 2–9 Calibration Mode. The Calibration mode allows you to adjust the instrument to factory specifications, if necessary . The Calibration mode is entered by pressing and holding the CONFIG button for a few seconds. The instrument adjustments are performed entirely from the front panel with the[...]

Operating Information 2–10 WFM 90 and WFM 91 Service Manual H The instrument software version number is displayed when the Configura- tion menu is open with the DISPLA Y category selected. H The LOW BA T message is displayed when the instrument is battery operated and the remaining battery power has reached a critically low level. The remaining l[...]

Theory of Operation[...]

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WFM 90 and WFM 91 Service Manual 3–1 Theory of Operation This section contains a module-level description of the instrument circuitry . Block Diagram Description The following description is based on the block diagram in Figure 3–1. The signal input and output connectors are located on the Input board. There are receivers for the three inputs, [...]

Theory of Operation 3–2 WFM 90 and WFM 91 Service Manual The Backlight Power Supply board uses the switched DC input voltage from the batteries or external DC input to generate the voltage for the display backlight. The backlight mounts into the display module. The LCD Display module generates the display graphics using input signals generated on[...]

Theory of Operation WFM 90 and WFM 91 Service Manual 3–3 16 Input Board Ref Va r Gain Ext Ref Audio In Video In Video Out Front Panel Keys Part of m P Rasterizer and Graphics V ert Defl Horiz Defl Instrument Control Bottom Board P/O T op Board LCD Display and Backlight Backlight Power Supply Board RGB P/O T op Board Part of m P Timing Subcarrier [...]

Theory of Operation 3–4 WFM 90 and WFM 91 Service Manual[...]

Performance V erification[...]

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WFM 90 and WFM 91 Service Manual 4–1 Performance V erification This section contains the following information: H Summary verification procedure H List of equipment required to perform the procedures H Performance verification procedures Summary V erification The summary verification is listed in T able 4–1 and is intended for those who are fam[...]

Performance V erification 4–2 WFM 90 and WFM 91 Service Manual T able 4–1: Summary verification procedure (Cont.) Procedure Page # Procedure Requirement V ector phase stability Phase Shift with Subcarrier Frequency Change from F SC to F SC  50 Hz (F SC  10 Hz P AL):  2 ° . Phase Shift with Burst Amplitude Change from Nominal to  6 [...]

Performance V erification WFM 90 and WFM 91 Service Manual 4–3 T able 4–2: Equipment required for performance verification (Cont.) Equipment Description Equipment Example Minimum Requirements Frequency counter Range: 10 Hz to 10 MHz; Accuracy:  0.001% T ektronix DC 503A 2 Universal Counter Video amplitude calibrator (V AC) Signal: Adjustable[...]

Performance V erification 4–4 WFM 90 and WFM 91 Service Manual Performance V erification Procedures Perform the performance verification procedures to ensure that the instrument is operating properly and is meeting the performance requirements listed in the characteristic tables of the Specifications section. Throughout these procedures the follo[...]

Performance V erification WFM 90 and WFM 91 Service Manual 4–5 Perform the following steps before beginning the verification procedures: 1. Plug the AC power adapter into the instrument and then plug the adapter into the AC power source. 2. Connect the multiburst signal from the television signal generator through a 75 W in-line terminator and du[...]

Performance V erification 4–6 WFM 90 and WFM 91 Service Manual This procedure verifies the following requirement: Sweep T iming Accuracy: 5 m s/Div . (1 Line), 10 m s/Div . (2 Line), and 1.0 m s/Div . (2 Line + MAG),  2%. 0.2 m s/Div . (1 Line + MAG)  3%. Integral Linearity:  1%. 1. Connect the multiburst signal from the television signa[...]

Performance V erification WFM 90 and WFM 91 Service Manual 4–7 This procedure verifies the following requirement: 1 V olt Full Scale: 1 V input displayed within 1% of 140 IRE (1.00 V P AL). X5 Gain: Gain accuracy within 5% with 1 V input signal. X5 Gain Registration:  1 major division of vertical shift from baseline between unmagnified and mag[...]

Performance V erification 4–8 WFM 90 and WFM 91 Service Manual 4. Set the V AC for a 799.9 mV output. 5. Check by adjusting the V ariable Gain controls that the signal amplitude can be displayed greater than 140 IRE (1000 mV P AL). 6. Select X5 GAIN from the Operating menu. 7. Set the V AC for a 399.9 mV output. 8. Enter the Configuration menu an[...]

Performance V erification WFM 90 and WFM 91 Service Manual 4–9 This procedure verifies the following requirement: X1 Gain Response (Flat filter selected): 50 kHz to 6 MHz within 2% of response at 50 kHz. X5 Gain Response (Flat filter selected): 50 kHz to 6 MHz within 5% of response at 50 kHz. Attenuation of 60 Hz (50 Hz P AL) on Input Signal: SLO[...]

Performance V erification 4–10 WFM 90 and WFM 91 Service Manual 17. Adjust the peak-to-peak detector Plus amplifier and input control fully counterclockwise. 18. Adjust the sine wave generator for a display amplitude of 100 IRE (700 mV P AL). 19. Note the digital multimeter readout level or the oscilloscope dc level. 20. Set the sine wave generat[...]

Performance V erification WFM 90 and WFM 91 Service Manual 4–1 1 This procedure verifies the following requirement: Phase Shift with Subcarrier Frequency Change from F SC to F SC  50 Hz (F SC  10 Hz P AL):  2 ° . Phase Shift with Burst Amplitude Change from Nominal to  6 dB:  2 ° . Phase Shift with V ariable Gain Control V aried [...]

Performance V erification 4–12 WFM 90 and WFM 91 Service Manual 3. Set the leveled sine wave generator frequency to 3.58 MHz (4.43 MHz P AL) and adjust the amplitude control so that the circle overlays the graticule compass rose. 4. Decrease the frequency on the leveled sine wave generator until the edge of the circle display reaches the –3 dB [...]

Performance V erification WFM 90 and WFM 91 Service Manual 4–13 11 . Check that the frequency readout on the leveled sine wave generator is between 3.98 and 4.18 MHz (4.83 and 5.03 MHz P AL). 12. Remove all signals from the WFM 90 or WFM 91 Handheld W aveform, V ector , Picture, and Audio Monitor . This procedure verifies the following requiremen[...]

Performance V erification 4–14 WFM 90 and WFM 91 Service Manual 15. Set the audio generator for a 50 Hz tone output, with an amplitude of +8.0 dBu. 16. Select 8 dBu from the Operating menu. 17. Check that the display amplitude is within 0.5 dB of the reference level graticule lines. 18. Set the audio generator frequency to 5 kHz. 19. Check that t[...]

Adjustment Procedures[...]

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WFM 90 and WFM 91 Service Manual 5–1 Adjustment Procedures This section contains the following information: H Summary adjustment procedure H List of equipment required to perform the procedures H Adjustment procedures Summary Adjustment T able 5–1 is the summary adjustment procedure and is intended for those who are familiar with the complete a[...]

Adjustment Procedures 5–2 WFM 90 and WFM 91 Service Manual Equipment Required T able 5–2 lists the required equipment and accessory items to perform the adjustment procedures. Minimum equipment specifications are followed by an example of equipment that meet these specifications. T able 5–2: Equipment required for performance verification Equ[...]

Adjustment Procedures WFM 90 and WFM 91 Service Manual 5–3 Adjustment Procedures The WFM 90 or WFM 91 Handheld W aveform, V ector , Picture, and Audio Monitor does not have any internal adjustments. Instrument adjustments are made entirely from the front panel by assigning adjustment functions to the Arrow Buttons through the Calibration menu. Th[...]

Adjustment Procedures 5–4 WFM 90 and WFM 91 Service Manual The following information provides you with an overview of how adjustments are made on the WFM 90 or WFM 91 Handheld W aveform, V ector, Picture, and Audio Monitor . Calibration Menu. T o enter the Calibration menu, press and hold the CONFIG button for a few seconds. The Calibration menu [...]

Adjustment Procedures WFM 90 and WFM 91 Service Manual 5–5 Perform the following steps to adjust the sweep timing and horizontal mag registration: 1. Replace the signal on the VIDEO IN connector with the output from the function generator . Be sure to use a 50 W -to-75 W minimum-loss attenuator and a precision (1%) 50 W cable if the generator spe[...]

Adjustment Procedures 5–6 WFM 90 and WFM 91 Service Manual 22. Adjust the Arrow Buttons for a sweep length of 12 major divisions. 23. Select CAL MENU , and then select SA VE . 24. Select 2H SWEEP from the Operating menu. 25. Select MAG REG from the Calibration menu, and then select CAL . 26. Select POS , and then use the Arrow Buttons to position[...]

Adjustment Procedures WFM 90 and WFM 91 Service Manual 5–7 14. Select X5 GAIN from the Calibration menu, and then select X5 POS . 15. Adjust the Arrow Buttons to reposition the signal baseline back to the graticule baseline. 16. Select X1 GAIN from the Calibration menu. 17. Select CAL MENU , and then select SA VE . 18. Remove the signal and termi[...]

Adjustment Procedures 5–8 WFM 90 and WFM 91 Service Manual 16. Set the leveled sine wave generator frequency to 50 kHz, and adjust the generator amplitude for exactly 100 IRE (700 mV P AL) of display . 17. Adjust the peak-to-peak detector Plus amplifier and input control fully counterclockwise. 18. Note the digital multimeter readout level or the[...]

Adjustment Procedures WFM 90 and WFM 91 Service Manual 5–9 Perform the following steps to adjust the vector gain and X5 gain phase: a. WFM 90 ONL Y — V erify that the television signal generator has setup turned on. b. Select VEC GAIN from the Calibration menu, select CAL , and then select TEST ON . c. Adjust the Y and B buttons so that the vec[...]

Adjustment Procedures 5–10 WFM 90 and WFM 91 Service Manual Perform the following steps to adjust the audio gain: 1. Connect the output from the audio generator to the AUDIO IN connector . 2. Set the audio generator for a 1 kHz tone output with an amplitude of +8.0 dBu. Select Signal On from the audio generator . 3. Select the AUDIO display mode [...]

Maintenance[...]

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WFM 90 and WFM 91 Service Manual 6–1 Maintenance This section contains instructions for servicing the WFM 90 or WFM 91 Handheld W aveform, V ector , Picture, and Audio Monitor that include the following information: H Preparation procedures to observe before performing maintenance H Procedures for inspecting and cleaning the instrument H Module r[...]

Maintenance 6–2 WFM 90 and WFM 91 Service Manual This instrument contains electrical components that are susceptible to damage from electrostatic discharge. Static voltages of 1 kV to 30 kV are common in unprotected environments. CAUTION. Static dischar ge can damage any semiconductor component in this instrument. Observe the following precaution[...]

Maintenance WFM 90 and WFM 91 Service Manual 6–3 Inspection and Cleaning Preventive maintenance consists of cleaning, visual inspection, performance checking, and, if needed, readjustment. The preventive maintenance schedule established for the instrument should be based on the environment in which it is operated and the amount of use. Under aver[...]

Maintenance 6–4 WFM 90 and WFM 91 Service Manual After cleaning, carefully check the instrument for defective connections, damaged parts, and improperly seated transistors or integrated circuits. The remedy for most visible defects is obvious; however , if heat-damaged parts are discovered, determine the cause of overheating before replacing the [...]

WFM 90 and WFM 91 Service Manual 6–5 Removal and Replacement This section contains the instructions on how you can remove and replace the customer replaceable modules and parts of the WFM 90 or WFM 91 Handheld W aveform, V ector , Picture, and Audio Monitor . CAUTION. T o pr event damage to the instrument, disconnect the power adapter and r emove[...]

Removal and Replacement 6–6 WFM 90 and WFM 91 Service Manual Procedures T able 6–2 lists the removal and replacement procedures in this section and their starting page numbers. T able 6–2: Removal and replacement procedure list Replaceable part Page number T op cover 6–7 LCD display lens 6–8 LCD display 6–9 LCD display padding 6–1 1 B[...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–7 The top cover assembly contains replaceable subparts. Procedures for removing the subparts are included below . T op Cover . T o remove the top cover assembly , perform the following procedure: 1. Remove the six retaining screws using the T orx-tip screwdriver . See Figure 6–1. Remove[...]

Removal and Replacement 6–8 WFM 90 and WFM 91 Service Manual 2. Gently lift the top cover off of the bottom cover . NOTE . When you ar e disassembling the WFM 90 or WFM 91, do not let dust accumulate inside of the top cover . Set the top cover face up on your work surface or cover it with a lint-fr ee cloth to pr event dust from accumulating on t[...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–9 LCD Display . T o remove the LCD display assembly , perform the following procedure: 1. Remove the top cover . Refer to T op Cover on page 6–7. 2. Disconnect the wires from the two backlight connectors. 3. Grasp the sides of the LCD display to lift it up off of the locating feet and d[...]

Removal and Replacement 6–10 WFM 90 and WFM 91 Service Manual NOTE . Some early instruments used cushion pads instead of locating feet to hold the display module in position. If your instrument has cushion pads, r eplace the pads at this time with locating feet. Contact your local T ektr onix repr esentative to or der the necessary parts. T o rep[...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–1 1 Level the pad flush with display case. LCD locator feet (4) Long pad Short pad Standoff post inserts into LCD display case. Figure 6–3: Installing the LCD display LCD Display Padding. T o remove the LCD display padding, perform the following procedure: 1. Remove the top cover . Refe[...]

Removal and Replacement 6–12 WFM 90 and WFM 91 Service Manual 3. Remove the display padding from the side of the LCD display module. 4. Clean any remaining glue residue from the side of the LCD display module. Refer to Cleaning on page 6–3. T o replace the LCD display padding, perform the following procedure: 1. Peel the protective cover from t[...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–13 The T op board assembly contains replaceable subparts. Procedures for removing the subparts are included below . T op Board. T o remove the T op board, perform the following procedure: 1. Remove the top cover . Refer to T op Cover on page 6–7. 2. Remove the two retaining screws from [...]

Removal and Replacement 6–14 WFM 90 and WFM 91 Service Manual Pull nub through board with tweezers Keypad T op board Figure 6–4: Installing the keypad 3. Install the T op board. Refer to T op Boar d on page 6–13. 4. Install the top cover . Refer to T op Cover on page 6–7. T op Board Shield. T o remove the T op board shield, perform the foll[...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–15 Lift up the board to slip the shield underneath the top board. Shield Fold tab The shield tab goes on top of the board post and under the circuit board. Figure 6–5: Installing the T op board shield 2. Slide the shield under the T op board and align the cutouts in the shield with the [...]

Removal and Replacement 6–16 WFM 90 and WFM 91 Service Manual T o remove the Bottom board, perform the following procedure: 1. Remove the top cover . Refer to T op Cover on page 6–7. 2. Remove the LCD display module. Refer to LCD Display on page 6–9. 3. Remove the T op board. Refer to T op Boar d on page 6–13. 4. Remove the battery cover . [...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–17 Align the Backlight and Input boards into the slots of the bottom cover Backlight board Input board assembly Figure 6–6: Installing the Bottom board T o remove the Backlight board, perform the following procedure: 1. Remove the top cover . Refer to T op Cover on page 6–7. 2. Remove[...]

Removal and Replacement 6–18 WFM 90 and WFM 91 Service Manual 4. Install the T op board. Refer to T op Boar d on page 6–13. 5. Install the LCD display module. Refer to LCD Display on page 6–9. 6. Install the top cover . Refer to T op Cover on page 6–7. 7. Install the battery cover . Refer to Battery Cover on page 6–18. T o remove the Inpu[...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–19 T o replace the battery cover assembly , perform the following procedure: 1. Place the lower lip of the battery cover into the instrument housing and press the top portion of the cover into the instrument. See Figure 6–7. Battery Cover Figure 6–7: Installing the battery cover 2. Se[...]

Removal and Replacement 6–20 WFM 90 and WFM 91 Service Manual T o replace the carrying strap, perform the following procedure: 1. Insert the two standoff studs of the carrying strap through the battery cover and install the two retaining nuts. 2. Install the battery cover . Refer to Battery Cover on page 6–18. T urnlock Stud and Bushing. T o re[...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–21 T o replace the turnlock stud and bushing, perform the following procedure: 1. Press the turnlock stud into the bushing. 2. T o install the turnlock stud and bushing into the battery cover , press firmly on the turnlock stud head. Be sure to keep the bushing head level with the battery[...]

Removal and Replacement 6–22 WFM 90 and WFM 91 Service Manual Press Grasp wire Figure 6–9: Removing the NiCad battery pack T o replace the NiCad battery pack, perform the following procedure: 1. Press the battery connector onto the jumper in the battery compartment. Be sure the battery connector tab snaps onto the jumper housing to prevent a lo[...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–23 T o replace the C-size alkaline batteries, perform the following procedure: 1. Press the batteries into place according to the polarity label on the bottom of the battery compartment. See Figure 6–10. NOTE . The polarity of the alkaline batteries must be corr ect for the instrument t[...]

Removal and Replacement 6–24 WFM 90 and WFM 91 Service Manual 4. Lift the Bottom board slightly out of the top cover so that you can pull the battery-power wires from jumper J21 of the Bottom board. See Figure 6–12. T o replace the bottom cover , perform the following procedure: 1. Lift the Bottom board slightly out of the top cover so that you[...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–25 Alignment ridge Retaining lip Battery contacts Figure 6–1 1: Battery contact installation alignment 4. Push the battery contact through the slot on the bottom cover . T o replace the battery contacts, perform the following procedure: 1. Align the slot in the battery contact with the [...]

Removal and Replacement 6–26 WFM 90 and WFM 91 Service Manual Depress receptacle prongs T urnlock stud receptacle Black wire Red wire Solder only this side Receptacle prongs Figure 6–12: Battery power-wire and turnlock stud receptacle installation 4. Install the bottom cover . Refer to Bottom Cover on page 6–23. T urnlock Stud Receptacle. T o[...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–27 T o replace the turnlock stud receptacle, perform the following procedure: 1. Push the turnlock stud receptacle through the bottom cover . Be sure the retaining fingers snap into position. See Figure 6–12. 2. Install the bottom cover . Refer to Bottom Cover on page 6–23. Bottom Cov[...]

Removal and Replacement 6–28 WFM 90 and WFM 91 Service Manual T o replace the battery orientation marker and/or the battery cushion pad, perform the following procedure: 1. T o replace the battery cushion pad and the battery orientation marker , peel off the protective covering of the adhesive surface of the battery cushion pad. 2. Position the b[...]

Removal and Replacement WFM 90 and WFM 91 Service Manual 6–29 4. Peel off the protective covering of the adhesive surface of the battery orientation marker . 5. Position the battery orientation marker in place above the battery cushion pad before you press it onto the battery cushion pad. See Figure 6–13. 6. Rub your fingers over the battery or[...]

Removal and Replacement 6–30 WFM 90 and WFM 91 Service Manual[...]

WFM 90 and WFM 91 Service Manual 6–31 T roubleshooting Procedures This section contains the following information starting on the listed pages: H List of equipment required to perform the procedures, this page H Battery-fault analysis, page 6–32 H Low-voltage power supply , page 6–34 H Fault symptom table, page 6–35 H T roubleshooting flowc[...]

T roubleshooting Procedures 6–32 WFM 90 and WFM 91 Service Manual Battery-Fault Analysis Use this procedure to troubleshoot battery or battery charging problems when the instrument functions properly when powered by the AC adapter . If there are no battery problems or if the instrument does not function properly with the AC adapter , go to Low-V [...]

T roubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–33 NOTE . If the jumper wir es will not stay secur ely attached to the battery connector pins, you will need to r emove the instrument bottom case to obtain access to the battery connector pins on the Bottom boar d. Refer to Bottom Cover on page 6–23. 4. Attach the voltmeter across [...]

T roubleshooting Procedures 6–34 WFM 90 and WFM 91 Service Manual NOTE . If the jumper wir es will not stay secur ely attached to the battery connector pins, you will need to r emove the instrument bottom case to obtain access to the battery connector pins on the Bottom boar d. Refer to Bottom Cover on page 6–23. 4. Attach the voltmeter across [...]

T roubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–35 T able 6–4: Low-voltage power supplies Supply T est Point Output Ripple +8 V J9, pin 13  40 mV 30 mV –8 V J9, pin 14  40 mV 30 mV +5 V J9, pin 15  25 mV 60 mV 6. If the low-voltage power supplies are operating properly , proceed to Fault Symptom T able . 7. If any of t[...]

T roubleshooting Procedures 6–36 WFM 90 and WFM 91 Service Manual 6. Connect a 75% color bar test signal to the VIDEO IN connector and connect the VIDEO OUT connector to the picture monitor . 7. Locate your fault symptom in T able 6–5 and go to the flowchart indicated to isolate the faulty module. T able 6–5: Fault symptom table Symptom Flowc[...]

T roubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–37 Is the Backlight broken? (The Display module will have a rattle inside.) Press the front panel ON button and then the PIX mode button. Is the Backlight on? (Look in the end of the Display module where the high voltage is attached.) Replace the Backlight in the Display module. Repla[...]

T roubleshooting Procedures 6–38 WFM 90 and WFM 91 Service Manual Use this procedure when the graticule is ok, but the Waveform display is distorted or not visible. Remove the Display module and Backlight board. Power up the instrument and select DEF AUL T PRESET s from the CONFIGURE menu. Select the Waveform display mode. Is the VIDEO IN signal [...]

T roubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–39 Use this procedure when the graticule is ok, but there is no V ector display . Remove the Display module and Backlight board. Power up the instrument and select DEF AUL T PRESET s from the CONFIGURE menu. Select V ector display mode. Is the VIDEO IN signal ok? No Ye s No Ye s Go to[...]

T roubleshooting Procedures 6–40 WFM 90 and WFM 91 Service Manual Use this procedure when the graticule is ok, but the Audio display is distorted or not visible. Remove the Display module and the Backlight board. Power up the instrument and select DEF AUL T PRESET s from the CONFIGURE menu. Select the Audio display mode. Attach an audio input sig[...]

T roubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–41 Replace the T op board. Replace the Bottom board. Are the Display drive signals ok? Check the Display drive signals: (Probe J16 from the back of the Bottom board.) J16-6 = (B) 2 VDC, 2.5 V peak video J16-7 = (G) 2 VDC, 2.5 V peak video J16-8 = (R) 2 VDC, 2.5 V peak video Is there a[...]

T roubleshooting Procedures 6–42 WFM 90 and WFM 91 Service Manual Use this procedure when the graticule and menu are bad, but the PIX mode is ok (moderate to severe vertical flutter). No Ye s Perform the Raster VCO adjustment, if possible, in the Adjustment procedures. Check the Raster VCO control signal: (J9 is on the T op board.) J9-6 = Approxi[...]

T roubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–43 Replace the Bottom board. Are all of these signals correct? Replace the Display module. Use this procedure when the display is all white. Remove the Display module and Backlight board. Connect the AC Adapter and power up the instrument. No Ye s Check the Display drive signals: (Pro[...]

T roubleshooting Procedures 6–44 WFM 90 and WFM 91 Service Manual Are the sync pulses ok? Replace the T op board. Check for vertical and horizontal sync pulses: (J9 is on T op Board.) J9-18 = TTL level V -rate sync locked to the input signal. J9-19 = TTL level H-rate sync locked to the input signal. Remove the Display module and Backlight board. [...]

T roubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–45 Use this procedure when the V ector display is unlocked. Remove the Display module and Backlight board. Connect the AC Adapter and power up the instrument. Select INT REF using the CONFIGURE menu. No Ye s Is the Waveform display triggered? Check the Subcarrier Regenerator Oscillato[...]

T roubleshooting Procedures 6–46 WFM 90 and WFM 91 Service Manual Use this procedure when there is V ector display jitter . This problem can be caused by either the T op or Bottom boards, and can only be determined by replacing these boards one at a time. Figure 6–26: Flowchart for vector display jitter Use this procedure when the vectors are d[...]

T roubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–47 Use this procedure when there is an instrument control problem. Ye s Replace the T op Board first. These problems can be caused by either the T op or Bottom boards, and can only be determined by replacing these boards one at a time. Do menu selections change as the front panel butt[...]

T roubleshooting Procedures 6–48 WFM 90 and WFM 91 Service Manual Use this procedure when the menus are horizontally unlocked (tearing) in the Picture display mode. Ye s No Check the horizontal and vertical sync signals on the Bottom board: (J9 is on T op board.) J9-18 = VSYNC is a TTL Level (locked to Video IN V -sync) J9-19 = HSYNC is a TTL Lev[...]

T roubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–49 Use this procedure when the display is dim or blotchy . Replace the Backlight in the Display module. Figure 6–30: Flowchart for dim or blotchy display Use this procedure when all of the display modes are bad except Picture when no menus are displayed. Replace the T op board. Figu[...]

T roubleshooting Procedures 6–50 WFM 90 and WFM 91 Service Manual Connector Diagram Figure 6–32 illustrates the connector and pin locations of the circuit board connectors listed in the troubleshooting flowcharts. J15 J14 J20 Bottom board To p board J16 J9 J16 as seen from the back of the Bottom board J9 as seen from the front of the T op board[...]

Options[...]

[...]

WFM 90 and WFM 91 Service Manual 7–1 Options and Accessories This section lists the instrument options and accessories that can be ordered for the WFM 90 or WFM 91 Handheld W aveform, V ector, Picture, and Audio Monitor . Refer to Parts Or dering Information on page 8–1 for information on how to order parts for this instrument. Refer to Replace[...]

Options and Accessories 7–2 WFM 90 and WFM 91 Service Manual Accessories The standard accessories are shipped with every instrument while the optional accessories must be ordered separately . The part numbers to use when you order any of the following accessories are listed in Mechanical Parts List on page 8–7. The standard accessories for the [...]

Replaceable Parts[...]

[...]

WFM 90 and WFM 91 Service Manual 8–1 Replaceable Parts List This section contains a list of the replaceable modules for this instrument. Use this list to identify and order replacement parts. Parts Ordering Information Replacement parts are available through your local T ektronix, Inc., Field Office or representative. Changes to T ektronix instru[...]

Replaceable Parts List 8–2 WFM 90 and WFM 91 Service Manual Using the Replaceable Parts List T able 8–1 describes each column in the replaceable parts list. T able 8–1: Replaceable parts list column descriptions Column Name Description Fig. & Index Number Items in this column are referenced to the exploded view item numbers. T ektronix Pa[...]

Replaceable Parts List WFM 90 and WFM 91 Service Manual 8–3 Manufacturers Cross Index Mfr . Code Manufacturer Address City , State, Zip Code 0DWW6 MICRO POWER ELECTRONICS 7973 SW CIRRUS DRIVE BLDG 22 BEA VERTON, OR 97008 0GV90 GLOBTEK INC 186 VETERANS DRIVE NORTHV ALE, NJ 07647–2303 0KB01 ST AUFFER SUPPL Y CO 810 SE SHERMAN PORTLAND, OR 97214?[...]

Replaceable Parts List 8–4 WFM 90 and WFM 91 Service Manual A2 A3 A4 A5 A1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 Figure 8–1: Exploded view[...]

Replaceable Parts List WFM 90 and WFM 91 Service Manual 8–5 Replaceable Parts List Fig. & Index Number T ektronix Part Number Serial No. Effective Serial No. Discont’d Qty Name & Description Mfr. Code Mfr . Part Number 10–1 202–0338–10 1 CASE,T OP:POL YCARBONA TE,WFM90 80009 202–0338–00 202–0338–20 1 CASE,T OP:POL YCARBONA[...]

Replaceable Parts List 8–6 WFM 90 and WFM 91 Service Manual Replaceable Parts List (Cont.) Fig. & Index Number Mfr . Part Number Mfr . Code Name & Description Qty Serial No. Discont’d Serial No. Effective T ektronix Part Number 671–3045–03 B030000 1 CIRCUIT BD ASSY :BACKLIGHT ,WFM91 80009 671–3045–03 –20 337–4000–00 1 SHEI[...]

Replaceable Parts List WFM 90 and WFM 91 Service Manual 8–7 Replaceable Parts List (Cont.) Fig. & Index Number Mfr . Part Number Mfr . Code Name & Description Qty Serial No. Discont’d Serial No. Effective T ektronix Part Number 671–3042–06 B023842 1 CIRCUIT BD ASSY :T OP BOARD,WFM90 80009 671–3042–06 671–3264–01 B010100 B010[...]

Replaceable Parts List 8–8 WFM 90 and WFM 91 Service Manual Replaceable Parts List (Cont.) Fig. & Index Number Mfr . Part Number Mfr . Code Name & Description Qty Serial No. Discont’d Serial No. Effective T ektronix Part Number 016–1344–00 1 CASE,CARR YING:CUST OM CASE FOR WFM90 , TSG90 80009 016–1344–00 1 19–4540–00 1 POWER[...]

Diagrams[...]

[...]

WFM 90 and WFM 91 Service Manual 9–1 Diagrams This section contains the interconnect diagram for the WFM 90 and WFM 91 Handheld W aveform, V ector , Picture, and Audio Monitor . A3 Bottom Board 10 A1 Input Board 60 10 J9 J2 J20 J19 J1 1 A2 T op Board 12 20 J16 A5 LCD Display Module Video In J4 Ref In J5 Video Out J6 Audio In J7 J14 10 J12 J15 A4 [...]

Diagrams 9–2 WFM 90 and WFM 91 Service Manual[...]