Page 3 - WARRANTY
WARRANTY Tektronix warrants that the products that it manufactures and sells will be free from defects in materials and workmanshipfor a period of one (1) year from the date of shipment. If a product proves defective during this warranty period, Tektronix,at its option, either will repair the defect...
Page 5 - Service Assurance; Service Assurance Advantages
Service Assurance If you have not already purchased Service Assurance for this product, you may do so at any time during the product’swarranty period. Service Assurance provides Repair Protection and Calibration Services to meet your needs. Repair Protection extends priority repair services beyond t...
Page 7 - WFM 90 and WFM 91 Service Manual; Table of Contents
WFM 90 and WFM 91 Service Manual i Table of Contents General Safety Summary vii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Service Safety Summary xi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preface xiii . . . . . . . . . . . . . . . . . ....
Page 8 - ii; Options
Table of Contents ii WFM 90 and WFM 91 Service Manual Fault Symptom Table 6–35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Troubleshooting Flowcharts 6–36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Connector Diagr...
Page 9 - iii; List of Figures
Table 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 front panel 2–4 . ...
Page 10 - iv
Table 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 untriggered waveform display 6–44 . . . . . . . . Figure 6–25: Flowchart for unlocked vector display 6–45 . . . . . . . . . . . ....
Page 11 - List of Tables
Table of Contents WFM 90 and WFM 91 Service Manual v List of Tables Table 1–1: Vertical deflection system 1–6 . . . . . . . . . . . . . . . . . . . . . . . . . . Table 1–2: DC restoration 1–7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 1–3: Audio mode 1–7 . . . . . . ...
Page 13 - General Safety Summary; Only qualified personnel should perform service procedures.; To Avoid Fire or Shock Hazards:
WFM 90 & WFM 91 Service Manual vii General Safety Summary Review the following safety precautions to avoid injury and prevent damage tothis product or any products connected to it. Only qualified personnel should perform service procedures. To avoid potential hazards, use this product only as sp...
Page 14 - Observe These Battery
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 off and disconnect th...
Page 15 - in injury or loss of life.; Terms on the Product.; Symbols and Terms
General Safety Summary WFM 90 & WFM 91 Service Manual ix Terms in this Manual. These terms may appear in this manual: WARNING. Warning statements identify conditions or practices that could result in injury or loss of life. CAUTION. Caution statements identify conditions or practices that could ...
Page 17 - WFM 90 & WFM 91 Service Manual; xi; Service Safety Summary; Do Not Service Alone.; Do not perform internal service or adjustments of this; Use Care When Servicing With Power On.; Dangerous voltages or currents may
WFM 90 & WFM 91 Service Manual xi Service Safety Summary Only qualified personnel should perform service procedures. Read this ServiceSafety Summary and the General Safety Summary before performing any serviceprocedures. Do Not Service Alone. Do not perform internal service or adjustments of thi...
Page 18 - xii
Service Safety Summary xii WFM 90 & WFM 91 Service Manual
Page 19 - xiii; Preface; About This Manual; This manual is composed of the following sections:; Related Manuals
WFM 90 and WFM 91 Service Manual xiii Preface This manual provides instructions for servicing the WFM 90 and WFM 91Handheld Waveform, Vector, Picture, and Audio Monitors. This manualdescribes features and specifications that are common to all generator modules.These include system configuration and ...
Page 20 - xiv
Page 21 - xv; Introduction; Service Strategy; NOTE; Service Offerings; Warranty Repair Service
WFM 90 and WFM 91 Service Manual xv Introduction Service Strategy NOTE . Throughout this manual, any field-replaceable component, assembly, or part of this oscilloscope is referred to generically as a module. This manual contains all the information needed for periodic maintenance of theWFM90 or WFM...
Page 22 - xvi; Repair or Calibration
Introduction xvi WFM 90 and WFM 91 Service Manual The following services may be purchased to tailor repair and/or calibration ofyour WFM90 or WFM91 Handheld Waveform, Vector, Picture, and AudioMonitor to fit your requirements: Option M2. When you order option M2, you receive a five year warranty and...
Page 23 - Before You Begin
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 Tektronix. The module shipped is repaired, tested,and returned to you from the Beaverton, Oregon service center. It is not updatedto match curre...
Page 24 - xviii
Introduction xviii WFM 90 and WFM 91 Service Manual
Page 25 - Specifications
Page 27 - Product Description; Key Features
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 Requirements on page 1–5 for the conditions over whichthe characteristics listed in this section are valid. Product Description The...
Page 28 - Description of Key
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 proprietaryrasterizer displays analog wavefo...
Page 30 - More Information
Specifications 1–4 WFM 90 and WFM 91 Service Manual Waveform-in-Picture Display Mode. The Waveform-in-Picture (WIP) display mode provides a 1/4-screen-sized window over the Picture display for any one ofthe Waveform, Vector, or Audio displays. The WIP window can be positioned toany one of the four c...
Page 31 - Characteristics Tables; Performance Requirement.; Req; Reference Information.; REF; Safety Standards
Specifications WFM 90 and WFM 91 Service Manual 1–5 Characteristics Tables 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 Pe...
Page 32 - Table 1–1: Vertical deflection system
Specifications 1–6 WFM 90 and WFM 91 Service Manual Table 1–1: Vertical deflection system Category Description Frequency Response REF: Specifications apply for full screen height video input signal with Vari-able Gain off. REQ: Flat Filter 1 V Full Scale: 50 kHz to 6 MHz within 2% of response at 50 ...
Page 33 - Table 1–2: DC restoration
Specifications WFM 90 and WFM 91 Service Manual 1–7 Table 1–1: Vertical 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 Ou...
Page 34 - Table 1–4: Horizontal deflection system; Table 1–5: Vector mode
Specifications 1–8 WFM 90 and WFM 91 Service Manual Table 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: Two Line and Two Field sweep length is nominally12 divisions. 1LINE Sweep ...
Page 36 - Table 1–6: Synchronization
Specifications 1–10 WFM 90 and WFM 91 Service Manual Table 1–6: Synchronization Category Description Input Requirements REQ: Internal Reference: Composite video or black burst with sync amplitudes40 IRE (300 mV PAL) 6 dB. REQ: External Reference: Sync amplitude between 143 mV and 4 V will synchro-ni...
Page 37 - Table 1–9: Power source
Specifications WFM 90 and WFM 91 Service Manual 1–11 Table 1–8: Environmental characteristics (Cont.) Category Description Vibration — Operating REF: 15 minutes each axis at 0.015 inch, frequency varied from 10 Hz to55 Hz to 10 Hz in 1-minute cycles with instrument secured to vibrationplatform. Ten ...
Page 39 - Operating Information
Page 41 - This section contains the following information:; Installation; The WFM 90 or WFM 91 Handheld Waveform, Vector, Picture, and; Mechanical Installation
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 Wavefo...
Page 42 - Figure 2–1: Installing the viewing hood; The optional desk stand provides the user with a stable means to; Figure 2–2: Installing the desk stand
Operating Information 2–2 WFM 90 and WFM 91 Service Manual ÏÏÏÏÏÏÏÏÏÏÏÏ ÏÏÏÏÏÏÏÏÏÏÏÏ ÏÏÏÏÏÏÏÏÏÏÏÏ ÏÏÏÏÏÏÏÏÏÏÏÏ ÏÏÏÏÏÏÏÏÏÏÏÏ ÏÏÏÏÏÏÏÏÏÏÏÏ ÏÏÏÏÏÏÏÏÏÏÏÏ ÏÏÏÏÏÏÏÏÏÏÏÏ Figure 2–1: Installing the viewing hood Desk Stand. The optional desk stand provides the user with a stable means to hold the instrument ...
Page 43 - Electrical Installation
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 unitproducing 12 VDC. CAU...
Page 44 - The instrument front panel is illustrated in Figure 2–3.; Figure 2–3: Instrument front panel; Front Panel Controls
Operating Information 2–4 WFM 90 and WFM 91 Service Manual Operating Information This section will acquaint you with the basic principles of operating thisinstrument so that you can service it. Detailed operating instructions are locatedin the user manual. The instrument front panel is illustrated i...
Page 45 - Display Mode Selection.
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 theinstrument is turned off using this button. NOTE . The instrument configuration is not saved if ...
Page 46 - Side-panel Connectors
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 Waveform and Audio display modes, they controlsignal positioning. For the Vector display mode, they control vector phase, withthe Y...
Page 47 - Figure 2–4: Instrument side panels; The DC IN power connector is a 2 mm plug which
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 +11 V to +18 V, using a negativecenter lead. CAUTION. To avoid possible damag...
Page 48 - Amplitude Alarm Mode.; The Amplitude Alarm mode provides a means to; Special Operating Modes
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 Waveform and Audiodisplays. This mode is enabled ...
Page 49 - Readout Description.; Listed below are the corresponding descriptions of the
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 pressingand holding the CONFIG button for a few seconds. The instrument adjustmentsare per...
Page 50 - Table 2–1: Front panel and menu default settings; Default Settings
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 DISPLAY category selected. H The LOW BAT message is displayed when the instrument is battery operatedand the remaining battery power has rea...
Page 51 - Theory of Operation
Page 53 - Block Diagram Description; The microprocessor takes input from the front-panel keypad to; Rasterizer and Graphics.; The rasterizer and graphics block produces all internally; Input Board
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 boar...
Page 54 - Backlight Power Supply
Theory of Operation 3–2 WFM 90 and WFM 91 Service Manual The Backlight Power Supply board uses the switched DC input voltage from thebatteries 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 dis...
Page 55 - Figure 3–1: Simplified block diagram
Theory of Operation WFM 90 and WFM 91 Service Manual 3–3 16 Input Board Ref Var Gain Ext Ref Audio In Video In Video Out Front Panel Keys Part of m P Rasterizer and Graphics VertDefl Horiz Defl Instrument Control Bottom Board P/O Top Board LCD Display and Backlight Backlight Power Supply Board RGB P...
Page 57 - Performance Verification
Page 59 - Summary Verification; Table 4–1: Summary verification procedure
WFM 90 and WFM 91 Service Manual 4–1 Performance Verification This section contains the following information: H Summary verification procedure H List of equipment required to perform the procedures H Performance verification procedures Summary Verification The summary verification is listed in Tabl...
Page 60 - Equipment Required; Table 4–2: Equipment required for performance verification
Performance Verification 4–2 WFM 90 and WFM 91 Service Manual Table 4–1: Summary verification procedure (Cont.) Procedure Page # Procedure Requirement Vector phase stability Phase Shift with Subcarrier Frequency Change from F SC to F SC 50 Hz (F SC 10 Hz PAL): 2 ° . Phase Shift with Burst Amplitude ...
Page 62 - Performance Verification Procedures; Conventions
Performance Verification 4–4 WFM 90 and WFM 91 Service Manual Performance Verification Procedures Perform the performance verification procedures to ensure that the instrument isoperating properly and is meeting the performance requirements listed in thecharacteristic tables of the Specifications se...
Page 63 - in-line terminator and dual-input coupler to the VIDEO IN and; Enter the Configuration menu and select the INPUT category.; Preliminary Setup
Performance Verification 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 gen...
Page 65 - Vertical Gain and Vertical
Performance Verification WFM 90 and WFM 91 Service Manual 4–7 This procedure verifies the following requirement: 1 Volt Full Scale: 1 V input displayed within 1% of 140 IRE (1.00 V PAL).X5 Gain: Gain accuracy within 5% with 1 V input signal. X5 Gain Registration: 1 major division of vertical shift f...
Page 66 - Select X5 GAIN from the Operating menu.; signal using a 75; Select VAR GAIN OFF from the Configuration menu.; This procedure verifies the following requirement:; Remove the pulse and bar signal from the VIDEO IN connector.; Overscan
Performance Verification 4–8 WFM 90 and WFM 91 Service Manual 4. Set the VAC for a 799.9 mV output. 5. Check by adjusting the Variable Gain controls that the signal amplitude can be displayed greater than 140 IRE (1000 mV PAL). 6. Select X5 GAIN from the Operating menu. 7. Set the VAC for a 399.9 mV...
Page 67 - Input and DC Restorer
Performance Verification 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 responseat 50 kHz. X5 Gain Response (Flat filter selected): 50 kHz to 6 MHz within 5%of response at 50 kHz. Attenuati...
Page 69 - Vector Phase Stability
Performance Verification WFM 90 and WFM 91 Service Manual 4–11 This procedure verifies the following requirement: Phase Shift with Subcarrier Frequency Change from F SC to F SC 50 Hz (F SC 10 Hz PAL): 2 ° . Phase Shift with Burst Amplitude Change from Nominal to 6 dB: 2 ° . Phase Shift with Variable...
Page 70 - Figure 4–1: –3 dB marks on the vector graticule
Performance Verification 4–12 WFM 90 and WFM 91 Service Manual 3. Set the leveled sine wave generator frequency to 3.58 MHz (4.43 MHz PAL) and adjust the amplitude control so that the circle overlays the graticulecompass rose. 4. Decrease the frequency on the leveled sine wave generator until the ed...
Page 71 - Audio Gain and
Performance Verification 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 PAL). 12. Remove all signals from the WFM 90 or WFM 91 Handheld Waveform, Vector, Picture, and Audio Monitor. This pr...
Page 72 - Select 8 dBu from the Operating menu.
Performance Verification 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...
Page 73 - Adjustment Procedures
Page 75 - Summary Adjustment; Table 5–1: Summary adjustment
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 Table 5–1 is the summary adjustment procedure and is intended f...
Page 76 - Table 5–2: Equipment required for performance verification
Adjustment Procedures 5–2 WFM 90 and WFM 91 Service Manual Equipment Required Table 5–2 lists the required equipment and accessory items to perform theadjustment procedures. Minimum equipment specifications are followed by anexample of equipment that meet these specifications. Table 5–2: Equipment r...
Page 78 - Plug the AC power adapter into the WFM 90 or WFM 91 Handheld; Perform the following steps to adjust the raster VCO:; Select RAST VCO from the Calibration menu.; Adjustment Methodology
Adjustment Procedures 5–4 WFM 90 and WFM 91 Service Manual The following information provides you with an overview of how adjustmentsare made on the WFM 90 or WFM 91 Handheld Waveform, Vector, Picture, andAudio Monitor. Calibration Menu. To enter the Calibration menu, press and hold the CONFIG butto...
Page 79 - Sweep Timing and
Adjustment Procedures WFM 90 and WFM 91 Service Manual 5–5 Perform the following steps to adjust the sweep timing and horizontal magregistration: 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 ...
Page 80 - Vertical Gain and X5 Gain
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 SAVE. 24. Select 2H SWEEP from the Operating menu. 25. Select MAG REG from the Calibration menu, and then select CAL. 26. Select POS,...
Page 81 - Frequency Response
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 ...
Page 82 - Vector Quadrature Phase
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 PAL) of display. 17. Adjust the peak-to-peak detector Plus amplifier and input control fully counterclockwise. 18. No...
Page 83 - b. Select VEC GAIN from the Calibration menu, select CAL, and then; Figure 5–1: NTSC graticule showing the vector gain adjustment; Vector Gain and X5 Gain
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 ONLY — Verify 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. ...
Page 84 - Select the AUDIO display mode on the WFM 90 or WFM 91 Handheld; dBu graticule lines.; Audio Gain
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 audi...
Page 85 - Maintenance
Page 87 - Procedures for inspecting and cleaning the instrument; Preparation; Servicing Prerequisites
WFM 90 and WFM 91 Service Manual 6–1 Maintenance This section contains instructions for servicing the WFM 90 or WFM 91Handheld Waveform, Vector, Picture, and Audio Monitor that include thefollowing information: H Preparation procedures to observe before performing maintenance H Procedures for inspec...
Page 88 - Electrostatic Damage
Maintenance 6–2 WFM 90 and WFM 91 Service Manual This instrument contains electrical components that are susceptible to damagefrom electrostatic discharge. Static voltages of 1 kV to 30 kV are common inunprotected environments. CAUTION. Static discharge can damage any semiconductor component in this...
Page 89 - Inspection and Cleaning; To avoid damage to this instrument, do not expose it to sprays,; General Care
Maintenance WFM 90 and WFM 91 Service Manual 6–3 Inspection and Cleaning Preventive maintenance consists of cleaning, visual inspection, performancechecking, and, if needed, readjustment. The preventive maintenance scheduleestablished for the instrument should be based on the environment in which it...
Page 90 - After Repair Adjustments; packaging materials are not available, follow these directions:; Visual Inspection
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. Theremedy for most visible defects is obvious; however, if heat-damaged parts arediscovered, determine th...
Page 91 - Removal and Replacement; To prevent damage to the instrument, disconnect the power adapter; Tools Required; Table 6–1: Tools required for module removal
WFM 90 and WFM 91 Service Manual 6–5 Removal and Replacement This section contains the instructions on how you can remove and replace thecustomer replaceable modules and parts of the WFM 90 or WFM 91 HandheldWaveform, Vector, Picture, and Audio Monitor. CAUTION. To prevent damage to the instrument, ...
Page 92 - Procedures; Table 6–2: Removal and replacement procedure list
Removal and Replacement 6–6 WFM 90 and WFM 91 Service Manual Procedures Table 6–2 lists the removal and replacement procedures in this section and theirstarting page numbers. Table 6–2: Removal and replacement procedure list Replaceable part Page number Top cover 6–7 LCD display lens 6–8 LCD display...
Page 93 - Figure 6–1: Removing the top cover; Top Cover Assembly
Removal and Replacement WFM 90 and WFM 91 Service Manual 6–7 The top cover assembly contains replaceable subparts. Procedures for removingthe subparts are included below. Top Cover. To remove the top cover assembly, perform the following procedure: 1. Remove the six retaining screws using the Torx-t...
Page 94 - Gently lift the top cover off of the bottom cover.; Install the six retaining screws using the Torx-tip screwdriver.; To avoid damaging the LCD display, do not touch the face of the; LCD Display Assembly
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 are 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 worksurface or cover it with a lint-free cl...
Page 95 - Disconnect the wires from the two backlight connectors.; disconnect the ribbon cable from the back of the display module.; Figure 6–2: Installing the LCD display cable
Removal and Replacement WFM 90 and WFM 91 Service Manual 6–9 LCD Display. To remove the LCD display assembly, perform the following procedure: 1. Remove the top cover. Refer to Top Cover on page 6–7. 2. Disconnect the wires from the two backlight connectors. 3. Grasp the sides of the LCD display to ...
Page 97 - Figure 6–3: Installing the LCD display; To remove the LCD display padding, perform the
Removal and Replacement WFM 90 and WFM 91 Service Manual 6–11 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. To remove the LCD display padding, perform the followi...
Page 98 - into the LCD display module.
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. To replace the LCD display padding, perform the following p...
Page 99 - Top Board Assembly
Removal and Replacement WFM 90 and WFM 91 Service Manual 6–13 The Top board assembly contains replaceable subparts. Procedures for removingthe subparts are included below. Top Board. To remove the Top board, perform the following procedure: 1. Remove the top cover. Refer to Top Cover on page 6–7. 2....
Page 100 - Figure 6–4: Installing the keypad; To remove the Top board shield, perform the following; Remove the two retaining screws from the top of the Top board.; To replace the Top board shield, perform the following procedure:
Removal and Replacement 6–14 WFM 90 and WFM 91 Service Manual Pull nub through board with tweezers Keypad Top board Figure 6–4: Installing the keypad 3. Install the Top board. Refer to Top Board on page 6–13. 4. Install the top cover. Refer to Top Cover on page 6–7. Top Board Shield. To remove the T...
Page 101 - Figure 6–5: Installing the Top board shield; the mounting posts of the Top board.; Install the two retaining screws into the top of the Top board.
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 Top board shield 2. Slide the shield under the Top board a...
Page 102 - Bottom Board
Removal and Replacement 6–16 WFM 90 and WFM 91 Service Manual To remove the Bottom board, perform the following procedure: 1. Remove the top cover. Refer to Top Cover on page 6–7. 2. Remove the LCD display module. Refer to LCD Display on page 6–9. 3. Remove the Top board. Refer to Top Board on page ...
Page 103 - Figure 6–6: Installing the Bottom board; To remove the Backlight board, perform the following procedure:; Gently pull the Backlight board from the back of the Bottom board.; To replace the Backlight board, perform the following procedure:; Install the Backlight board into the back of the Bottom board.; gently slide the boards into the bottom cover.; Backlight Board
Removal and Replacement WFM 90 and WFM 91 Service Manual 6–17 Align the Backlight andInput boards into theslots of the bottom cover Backlightboard Input board assembly Figure 6–6: Installing the Bottom board To remove the Backlight board, perform the following procedure: 1. Remove the top cover. Ref...
Page 105 - Figure 6–7: Installing the battery cover; To remove the carrying strap, perform the following procedure:
Removal and Replacement WFM 90 and WFM 91 Service Manual 6–19 To 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 Figu...
Page 106 - Install the battery cover. Refer to Battery Cover on page 6–18.; Turnlock Stud and Bushing.; Remove the battery cover. Refer to Battery Cover on page 6–18.; Gently pull and rock the turnlock stud while holding the bushing.; Figure 6–8: Removal and replacement of the turnlock stud
Removal and Replacement 6–20 WFM 90 and WFM 91 Service Manual To 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 p...
Page 107 - Press the turnlock stud into the bushing.; Install the battery cover. Refer to Battery Cover on page 6–18.; Battery Cushion Pad.; To remove the battery cushion pad, perform the following; Batteries
Removal and Replacement WFM 90 and WFM 91 Service Manual 6–21 To replace the turnlock stud and bushing, perform the following procedure: 1. Press the turnlock stud into the bushing. 2. To install the turnlock stud and bushing into the battery cover, press firmly on the turnlock stud head. Be sure to...
Page 108 - Figure 6–9: Removing the NiCad battery pack; Carefully pull the batteries out of the battery compartment.
Removal and Replacement 6–22 WFM 90 and WFM 91 Service Manual Press Grasp wire Figure 6–9: Removing the NiCad battery pack To 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 ...
Page 109 - Figure 6–10: Installed polarity of alkaline batteries; Remove the six Torx screws from the bottom cover.; cover, carefully remove the bottom cover; Bottom Cover Assembly
Removal and Replacement WFM 90 and WFM 91 Service Manual 6–23 To 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 ba...
Page 110 - Battery Power Connector.
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. To replace the bottom cover, perform the following procedure: 1. Lift the Bottom boa...
Page 111 - Figure 6–11: Battery contact installation alignment; To replace the battery contacts, perform the following procedure:
Removal and Replacement WFM 90 and WFM 91 Service Manual 6–25 Alignment ridge Retaining lip Battery contacts Figure 6–11: Battery contact installation alignment 4. Push the battery contact through the slot on the bottom cover. To replace the battery contacts, perform the following procedure: 1. Alig...
Page 112 - Turnlock Stud Receptacle.; To remove the turnlock stud receptacle, perform the
Removal and Replacement 6–26 WFM 90 and WFM 91 Service Manual Depress receptacle prongs Turnlock 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 113 - Install the bottom cover. Refer to Bottom Cover on page 6–23.; Bottom Cover Electrical Shield.; Remove the bottom cover. Refer to Bottom Cover on page 6–23.; Battery Orientation Marker and Battery Cushion Pad.
Removal and Replacement WFM 90 and WFM 91 Service Manual 6–27 To 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...
Page 114 - Figure 6–13: Battery orientation marker position
Removal and Replacement 6–28 WFM 90 and WFM 91 Service Manual To replace the battery orientation marker and/or the battery cushion pad, performthe following procedure: 1. To replace the battery cushion pad and the battery orientation marker, peel off the protective covering of the adhesive surface o...
Page 115 - Release the retaining latches on the side of the EMI suppressor.; Figure 6–14: Installing the EMI suppressor; AC Adapter EMI
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 ...
Page 117 - Troubleshooting Procedures; List of equipment required to perform the procedures, this page; Table 6–3: Equipment required for troubleshooting
WFM 90 and WFM 91 Service Manual 6–31 Troubleshooting 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 t...
Page 118 - Battery-Fault Analysis; Remove the AC adapter from the WFM 90 or WFM 91 Handheld Wave-; See Batteries on page 6–21.; Use three jumper wires to connect two 30; , 3 W resistors and an external; and Below
Troubleshooting Procedures 6–32 WFM 90 and WFM 91 Service Manual Battery-Fault Analysis Use this procedure to troubleshoot battery or battery charging problems when theinstrument functions properly when powered by the AC adapter. If there are nobattery problems or if the instrument does not function...
Page 119 - Attach the voltmeter across test resistor #1 in Figure 6–15.; and Above
Troubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–33 NOTE . If the jumper wires will not stay securely attached to the battery connector pins, you will need to remove the instrument bottom case to obtain access to thebattery connector pins on the Bottom board. Refer to Bottom Cover onpag...
Page 120 - Low-Voltage Power Supply
Troubleshooting Procedures 6–34 WFM 90 and WFM 91 Service Manual NOTE . If the jumper wires will not stay securely attached to the battery connector pins, you will need to remove the instrument bottom case to obtain access to thebattery connector pins on the Bottom board. Refer to Bottom Cover onpag...
Page 121 - Do not use a soldering iron larger than 18 W or you may damage the; Fault Symptom Table; Disconnect the AC adapter from the instrument.; Remove any installed batteries. See Batteries on page 6–21.; Secure the instrument circuit boards in the circuit board vise.
Troubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–35 Table 6–4: Low-voltage power supplies Supply Test 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 Sym...
Page 122 - Table 6–5: Fault symptom table; Troubleshooting Flowcharts
Troubleshooting 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 Table 6–5 and go to the flowchart indicated to isolate the faulty module. Tabl...
Page 123 - Figure 6–17: Flowchart for no display
Troubleshooting 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.) Rep...
Page 124 - Figure 6–18: Flowchart for distorted waveform display
Troubleshooting 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 Backlightboard. Power up the instrument and select DEFAULT PRESETs from the CONFIGURE menu. Select the Wav...
Page 125 - Figure 6–19: Flowchart for no vector display
Troubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–39 Use this procedure when the graticule is ok, but there is no Vector display. Remove the Display module and Backlightboard. Power up the instrument and select DEFAULT PRESETs from the CONFIGURE menu. Select Vector display mode. Is the V...
Page 126 - Figure 6–20: Flowchart for bad audio display
Troubleshooting 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 DEFAULT PRESETs from the CONFIGURE menu. Select the A...
Page 127 - Figure 6–21: Flowchart for no picture display
Troubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–41 Replace the Top 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 videoJ...
Page 128 - Figure 6–22: Flowchart for bad graticules and menus
Troubleshooting 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 Yes Perform the Raster VCO adjustment, if possible, in the Adjustment procedures. Check the Raster VCO control sig...
Page 129 - Figure 6–23: Flowchart for all white display
Troubleshooting 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...
Page 130 - Figure 6–24: Flowchart for untriggered waveform display
Troubleshooting Procedures 6–44 WFM 90 and WFM 91 Service Manual Are the sync pulses ok? Replace the Top board. Check for vertical and horizontal sync pulses: (J9 is on Top 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. Rem...
Page 131 - Figure 6–25: Flowchart for unlocked vector display
Troubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–45 Use this procedure when the Vector 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 Yes Is the Waveform display triggere...
Page 132 - Figure 6–26: Flowchart for vector display jitter; Figure 6–27: Flowchart for distorted vectors
Troubleshooting Procedures 6–46 WFM 90 and WFM 91 Service Manual Use this procedure when there is Vector display jitter. This problem can be caused by either the Top or Bottom boards, and can only be determined by replacing these boards one at a time. Figure 6–26: Flowchart for vector display jitter...
Page 133 - Figure 6–28: Flowchart for problems with the instrument controls
Troubleshooting Procedures WFM 90 and WFM 91 Service Manual 6–47 Use this procedure when there is an instrument control problem. Yes Replace the Top Board first. These problems can be caused by either the Top or Bottom boards, and can only be determined by replacing these boards one at a time. Do me...
Page 134 - Figure 6–29: Flowchart for bad menus in the picture display
Troubleshooting 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. Yes No Check the horizontal and vertical sync signals on the Bottom board: (J9 is on Top board.) J9-18 = VSYNC is a TTL Level (locked to...
Page 135 - Figure 6–30: Flowchart for dim or blotchy display
Troubleshooting 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...
Page 136 - Connector Diagram; Figure 6–32: Circuit board connector and pin locations
Troubleshooting Procedures 6–50 WFM 90 and WFM 91 Service Manual Connector Diagram Figure 6–32 illustrates the connector and pin locations of the circuit boardconnectors listed in the troubleshooting flowcharts. J15 J14 J20 Bottom board Top board J16 J9 J16 as seen from the back of the Bottom board ...
Page 139 - Options and Accessories
WFM 90 and WFM 91 Service Manual 7–1 Options and Accessories This section lists the instrument options and accessories that can be ordered forthe WFM 90 or WFM 91 Handheld Waveform, Vector, Picture, and AudioMonitor. Refer to Parts Ordering Information on page 8–1 for information onhow to order part...
Page 140 - Accessories; Standard Accessories
Options and Accessories 7–2 WFM 90 and WFM 91 Service Manual Accessories The standard accessories are shipped with every instrument while the optionalaccessories must be ordered separately. The part numbers to use when you order any of the following accessories arelisted in Mechanical Parts List on ...
Page 141 - Replaceable Parts
Page 143 - Replaceable Parts List; Parts Ordering Information; Part number; Module Servicing
WFM 90 and WFM 91 Service Manual 8–1 Replaceable Parts List This section contains a list of the replaceable modules for this instrument. Usethis list to identify and order replacement parts. Parts Ordering Information Replacement parts are available through your local Tektronix, Inc., Field Officeor...
Page 144 - Using the Replaceable Parts List; Table 8–1 describes each column in the replaceable parts list.; Table 8–1: Replaceable parts list column descriptions; Cross Index–Mfr. Code
Replaceable Parts List 8–2 WFM 90 and WFM 91 Service Manual Using the Replaceable Parts List Table 8–1 describes each column in the replaceable parts list. Table 8–1: Replaceable parts list column descriptions Column Name Description Fig. & Index Number Items in this column are referenced to the...
Page 145 - Manufacturers Cross Index
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 DRIVEBLDG 22 BEAVERTON, OR 97008 0GV90 GLOBTEK INC 186 VETERANS DRIVE NORTHVALE, NJ 07647–2303 0KB01 STAUFFER SUPPLY ...
Page 146 - Figure 8–1: Exploded view
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
Page 151 - Diagrams
Page 153 - Figure 9–1: Interconnect diagram
WFM 90 and WFM 91 Service Manual 9–1 Diagrams This section contains the interconnect diagram for the WFM 90 and WFM 91Handheld Waveform, Vector, Picture, and Audio Monitor. A3 Bottom Board 10 A1 Input Board 60 10 J9 J2 J20 J19 J11 A2 Top Board 12 20 J16 A5 LCD Display Module Video In J4 Ref In J5 Vi...
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