TVM-821D - TEquipment.NET
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1. 510617 cS8 NAL x ESSA 8 zuoH E1UOZIOH 10d uonejoH Hey 14021 GX JO X kejag uue v E1UOZIJOH 011U09 UONISOJ ou S lt x3 JO0jeJouor dwey Ben ESSA GX JO IX 4 indu Bojeuy o pny oeJels 59 019 Oa 1099A 011400 uonisog EIA 14614 oipny 1497 olpny 011400 I JosseooJdojJol A SIIE ki A owayy ino Bojeuy ul eu amp iq Buissod0Jd jeu is jeubig sq31 jeued 10014 SOY9 MS S1 1 d Bojeuy 5104 10199A 1 l uEd 1401 i SQOUM 011409 9ue y 1u0J4 AZI Ue nolle1o 8 S8 NA L OV A 9 ADO AOGLZ N0008 5804 12 Jamod 0 pas OV A 9 1001 AOGLZ 0008 A ddns AZL AG A ddns o eyon MO U9IIMS Jomod pue say sn oy NI OY 18 Block Diagram for TVM 850 Board AUG 19 ad 40 WAM NE Koneg uod zezsu pue Away Boa UEM eoejelu 9ue y 4014 Joy envog hejap A 998 3 u 1 H AUOD Qq v 0 3 lezijeueseq 39015 ZHW ZZ euJa u 019A 01 OF g lqeo OJIIIN 01 O3 sa Bojeuy2. 2 The CHANNEL button selects between the three components Y Cb Cr 3 Vector display is an X Y representation of the Cb and Cr compo nents respectively 4 Low Pass LP and Differential Step DS filter the selected Y Cb Cr channels 5 Bowtie DX displays a two line sweep of Y Cb and Y Cr While in RGB format the following applies 1 Waveform displays video inputs in a transcoded RGB format 2 The CHANNEL button selects between the three components R G B 3 The VIEW SAV EAV function is disabled while in the RGB format 4 Vector display is an X Y representation of the Cb and Cr compo nents respectively 5 Low Pass LP and Differential Step DS filter the selected R G B channels 6 Bowtie gt lt displays a two line sweep of Y Cb and Y Cr REAR PANEL The rear panel of the TVM 821D consists of four digital video input BNC connectors two analog video reference input BNC connectors a 15 pin audio GPI connector an AC power cord connector and a fan Two pairs of BNC connectors labeled SERIAL INPUT A and SERIAL INPUT B are for passively looping 601 digital video inputs There is one pair of BNC connectors for looping an external analog reference video input The 15 pin audio GPI connector is wired as shown below 1 X 9 CONTACT COMMON 2 GND 10 N C CONTACT 3 X 11 GPI 41 4 NC 12 GPI 2 bi 13 6 GND 14 GPI 4 7 Y 15 GPI COMMON 8 NO CONTACT PRINTED CIRCUIT BOARD MOUNTED CONTROL
3. Settings are per following chart Switch Position Audio Level 0 dBm 4 dBm 8 dBm 12 dBm TRACE ROTATION Before installing the unit in its final location check the trace rota tion The unit like any other CRT device is affected by the earth s magnetic field The trace might be rotated relative to the etched graticule depending upon the position of the instrument Place the unit in its final location and use H POS and V POS to position a horizontal trace relative to the O mV line of the graticule Adjust pot R229 to align horizontal trace with graticule FRONT OF UNIT Front amp Back Panel Controls SN D INPUT VIEW ag VIEWS B Dovr INTENSITY REF CHANNEL ower O EXT DISPLAY AUDIO GRAT wem O Don VEC L1 SWEEP HMAG LINE A 7 FIELD FOCUS FORMAT VMAG YCbcr r r H POS SAV EAV STORE oN O Dse wo FILTER memory O ALTER m V POS 03 x CAL vectrmt 4 on 7 100 VECTOR o 0 MIN EQ MAX ERROR REFERENCE POWER ap Ml 5250 TVM 821D s0 0 o o oe ee mi 625 0 Z FRONT VIEW LEFT CONTROL PANEL ternally generated precision 100 kHz square wave and a vector cen INTENSITY Knob which controls the brightness of the CRT beam GRAT Knob which controls the brightness of the graticule lights FOCUS Knob which co
4. a reconstruction filter and is buffered for output to the TVM 851 board R30 is used to adjust the WFM amplitude by adjusting the reference voltage to the DAC C37 is used to trim the frequency response of the waveforms Sheet 9 CPU and memory The 68HC11 U30 is used to perform the following tasks on pon Loads the programmable logic chips Controls the front panel LEDs and reads the front panel buttons Controls waveform vector and audio sweeps Using the built in A D converter it reads the amount of input equalization and displays the equalization on the front panel 5 Stores and recalls front panel setups Can recall setups using the four general purpose inputs 6 Activates alarm relay during EDH data or gamut errors The 68HC11 is supervised by U39 a watchdog timer The watchdog controls the reset line on the micro and the capacitor backup for the CPU and external RAM The watchdog can be disabled by removing jumper CN2 Two external interrupts to the micro are the Horizontal and Vertical syncs for the reference video The Horizonal sync is gated by U34 prior to going to the XIRQ a nonmaskable interrupt U34 allows the micro to turn off the nonmaskable interrupt while it pro grams the programmable logic CPU read and write strobe are generated by U34 pins 11 and 6 The serial port driver U33 is not used in this implementation U28 is used to gate the clocks which go to the programmable devices during start up R
5. boxes Equalization light Calibration Connect cable simulation box between video source and video inputs a Turn unit off b Power unit on with FILTER and MEMORY buttons de pressed Release buttons after EQ LEDs stop spinning c Press CAL First green LED for input A will flash d Set cable simulator for 0 meters Press CAL button and wait for next green LED to flash e Setcable simulator to 125 meters Press CAL button Wait until yellow LED for input A begins to flash f Set cable simulator for 0 meters Press CAL button and wait for next green LED to flash g Setcable simulator to 200 meters Press CAL button Wait until red LED for input A begins to flash h Setcable simulator to 225 meters Press CAL button Wait until first green LED for input B begins to flash i Set cable simulator to 125m Press CAL button Wait until yellow LED for input B begins to flash j Set cable simulator to 200m Press CAL button Wait until red LED for input B begins to flash k Set cable simulator to 225m Press CAL button Wait until red LED for input B stops flashing Turn unit off to exit this cal mode TURN UNIT ON Troubleshooting Procedure Unit appears to be dead no LEDs on graticule lights off and no CRT display Ensure power switch on front of unit is in the I position 1 Make sure power source to unit is live 2 Check that power cord is firmly seated into rear of unit 3 Check external fuse If b
6. deis jeyuessyia ssedmo7 eld pg 0S8 NAL WO indu uuoJ APAA Ja duy 2911194 s oy q Dojeuy uuojeAeM LUJOJ9AB M indu Bojeuy 20 NOTES 21 Performance Check TEST EQUIPMENT NEEDED Digital 601 Test Pattern Generator 2 Channel Audio Source PROCEDURE 1 Scope setup INPUT A so pappp o REF internal DISPLAY waveform and vector SWEEP line FORMAT YCbCr SAV EAV off FILTER off CAL off VIEW parade CHANNEL Y AUDIO off HMAG off VMAG off STORE off MEMORY off VECT FMT 75 off 2 Calibration Pulse check a Turn CAL on Ensure that calibration pulse goes from 0 mV to 700 mV Ensure that vector centering dot is in the center vector box 3 Color bar verification o ococo n Apply 7596 color bars to INPUT A Ensure that each bar measures the proper amplitude Ensure that all vectors fall into the proper boxes Apply 10096 color bars to INPUT A Change the VECT FMT to 10096 ON Ensure that each bar measures the proper amplitude Ensure that all vectors fall into the proper boxes 4 Audio Verification a b Go into audio only mode by pressing AUDIO and then DIS PLAY Apply a 4 dBm 6000 1 kHz sine wave in phase audio to both of the audio inputs Ensure the audio setting on the bottom of the unit is set to 4 dBm The audio should fall into the center of the audio boxes along the 45 line Set the audio to be 10 out of phase with one ano
7. in the analog circuitry 12 volts or 5 volts can be used to power the back panel fan using CN4 5V fan or CN15 12V fan TVM 851 BOARD Sheet 1 Analog video from the TVM 850 board enters the TVM 851 board via CN7 The signal is buffered by U39 which drives the vertical deflection selector U30 This switch selects between FLAT or unfiltered video and LOW PASS and DIFF STEP filtered video for waveform displays When the unit is in vector mode U30 selects VECY which is the component Cr for the vertical deflection of the vector display The output of U30 is connected to a 2x1 switch U29 which chooses between normal and amplified x5 video The output of U29 is amplified by U31 before entering the CRT deflection board The vertical position of the waveform display is controlled by varying the offset of U31 The offset voltage for U31 is selected by the second half of U30 which switches in a summation of the waveform vertical position voltage and a calibrated offset needed while in x5 amplitude mode Sheet 2 The external reference video enters the TVM 851 board via CN5 and CN6 U41 buffers the video signal into the sync separator circuit U33 is used to low pass filter the signal resulting in the elimination of any chroma information Comparators U40 and U32 and switches U36 form a precision 50 sync level slicing circuit which extracts a TTL level composite sync signal at pin 14 of U32 A one shot U20 is used to eliminate any vertical informati
8. interpolators double the effective data for the color difference channels This interpolation allows color space conversion of the video to be done digitally at a 4 4 4 rate in U17 U5 interpolates all waveform data from a 4x oversampling to 8x in a 12 bit format The waveforms include Y Cb Cr R G B calibration pulse and Bowtie Sheet 5 and 6 All symbols on these pages are for a single program mable device U17 This programmable device inputs Y data 4x oversampling Cb and Cr data 4x oversampling The WFM data is sent to interpolator U5 to increase the data rate to 8x oversampling The Cb and Cr data is sent directly to the DACs at a 4x oversampled rate for vector display This programmable device performs the following Converts YCbCr to RGB Gamut error detection Bowtie filter Waveform multiplexing 75 100 vector adjustment Y delay to compensate for CbCr interpolators Sheet 7 Vector DACs Digital Cb and Cr 4x oversampled are sent to the triple DAC U16 The analog outputs are sent through the reconstruction filters and buffered for output to the TVM 851 board R59 and C45 are used to trim the amplitude and frequency response of the Cb channel R64 and C48 are used to trim the amplitude and frequency response of the Cr channel Sheet 8 WFM DACs Digital data Y Cb Cr R G B calibration pulse and bowtie 8x oversampled is sent to the 12 bit DAC U6 The differential output is received by U2 sent through
9. line and field rate sweeps respectively U7 amplifies the ramp before entering the horizontal magnification amplifier on sheet 7 The offset of U7 is controlled by U23 and U22 U23 is used to control the waveform horizontal position U22 switches in different offsets needed for each cell of a paraded sweep Sheet 7 The waveform horizontal deflection ramp is amplified by U8 for the HMAG display mode U9 U10 Q1 and Q2 form a clipping circuit which limits the amplitude of the amplified ramp The ramp is then amplified by U11 before entering a switch U2 This switch selects between the normal and the amplified ramp for the selected display mode The ramp is then amplified by U3 before entering the deflection switch on sheet 5 Sheet 8 U37 and U38 are used to interface the TVM 851 board with the TVM 850 board External horizontal and vertical sync are output to the TVM 850 via U37 Mode selection bits from the CPU are input to the TVM 851 board via U37 and U38 U24 is a GAL which controls the operation of this board The power for this board is connected via CN13 Sheet 9 The differential audio channels are amplified by U42 before entering attenuators U43 is a 4x1 switch controlled by SW1 which selects the available audio amplitude ranges The outputs of U43 are amplified by U42 before entering the deflection switches on sheet 5 K1 is a relay controlled by Q12 which provides the general purpose output switch closure used to indicate the occ
10. overlay vievv the inputs appear overtop of each other 2 If all three channels are selected a In parade view the channels appear next to each other and each channel is an overlay of both inputs b In overlay view the channels and inputs all appear overtop of each other 12 SWEEP SELECTION The SWEEP button changes the CRT sweep rate between horizontal LINE and vertical FIELD rate Each press of the button toggles be tween the two rates HMAG SELECTION The HMAG button multiplies the current sweep rate by a factor of 10 Each press of the HMAG button toggles the magnification on and off The major horizontal divisions on the 0 mV line of the graticule are calibrated for the three horizontal sweep speeds 1H 2H and 3H With HMAG off they represent 5 0 10 0 and 15 0 uS respectively With HMAG on they represent 0 5 1 0 and 1 5 uS respectively CAL SELECTION A precision 100 kHz waveform is provided for verifying vertical gain and horizontal sweep timing In addition a dot is provided which re presents the vector origin for vectorscope centering To select the calibration mode simply press the CAL button A second press of the CAL button will toggle the calibration mode off returning the display to the previously selected mode Selecting the calibration mode will always force the display into a 1H sweep with the vector origin dot regardless of the configuration of the unit beforehand MEMORY PRESET STORAGE The TVM 821D all
11. spike at the end of each line The user will then be able to see how active video appears in relationship to these markers In addition when this function is enabled in A and B input mode the timing difference between SAV or EAV of each input can show timing differences between the channels EAV and SAV are disabled then in RGB mode AUDIO PHASE MARKINGS AUDIO TARGET BOXES VIDEOTEK K FACTOR MARKINGS VECTOR GRATICULE BOX GREEN BOX REPRESENTS 2 OF FULL SCALE VECTOR El m REPRESENTING 0 5 dB AND 1 0 dB AMPLITUDE ERRORS 1 El REFERENCE FOR 75 COLOR BARS AUDIO AND VECTOR CENTERING BOX oma CENTER FOR COLOR DIFFERENCE CHANNELS 8 WAVEFORM MAJOR GRATICULES SPACED EVERY 100 mV WAVEFORM MINOR GRATICULES SPACED EVERY 20 mV B T y 13 WAVEFORM MAJOR TIMING DIVISION SPACED EVERY 5 uS 1H SWEEP WAVEFORM MINOR TIMING DIVISION SPACED EVERY 1 HS 1H SWEEP Theory of Operation The TVM 821D is a combination waveform monitor and vectorscope Its display modes allow waveform and vector displays to be presented in any combination The basic signal flow and control structure of the TVM 821D may be seen in the interconnection diagram on page 27 The circuitry shown in the block diagram on page 18 is contained on six different printed circuit boards The boards and their primary functions are 1 TVM 850 converts two channels of componen
12. 84 approximately 12 The differential stage is made of Q5 Q2 and is biased by R80 Cur rent source Q3 is an active load for the gain stage Q4 making for nearly equal rise and fall times from the output contrasted with the Slow rise times that would characterize a resistively loaded amplifier C18 and C20 provide extra drive to Q3 during high speed signal tran sitions thereby enhancing the slew rate of the amplifier When the composite intensity signal ranging from 0 8 to 5V is passed through the amplifier the output range is about 10 to 60V this is sufficient to drive the CRT G1 over the range of cut off to maximum useful intensity Although the peak to peak voltage from the output of the intensity amplifier is sufficient to drive the CRT intensity grid the signal is not sitting at the proper DC level to properly bias the grid The CRT cath ode is biased at 2080V and the grid must be more negative than that to properly control intensity of the electron beam Therefore some sort of interface from the relatively low voltage intensity amp to the high voltage grid is required The necessary voltage isolation is provided by C17 with a working voltage rating of 4000V AC signals pass through C17 but a DC reference is required to properly bias G1 The method used is that of a diode clamp using D3 D4 Biasing is as follows 2200V from the power supply is passed through 120V zener diode D9 to make the 2080V cathode bias voltage This m
13. E dido ARS of d y r GC eed bc SI od e ER 7 8 Installation Instructions ue Ene e Een sae Ae Cere E oe RC 9 Front amp Back Panel Controls an e RV EE EE XXE CA Kein 10 Operating instructions vlt UE RR DU RI E kd Edu e NEN 12 Theory of Operations eicit eo a SAS e caf eC ra ee 14 Block DI38ram an a ett datu ikea dd 18 Block Diagram for TVM 850 Board 19 Block Diagram for TVM 851 Board 20 Performance C Heck sa E a an ei a Mumm sma 22 Calibration Procedure 24 Troubleshooting Procedure 25 nterconnectie DISPram AAA ea ot ec A 21 TVM 850 Component Layout 30 TVM 850 Board Schematic 32 TVM 851 Component Layout 46 TVM 851 Board SCHEMA penas ice qns ra ha poa u 48 TVM 852 Component Layout 57 TVM 852 Board Schematie ee Ep ke eke eee ee Nep AR 58 TYM 853 Component Layout 62 TVINI S53 Board Schematic suco Toe a ey adeb ae 63 Parisi tos na ente sasana sasa oe t nara sabeis mia E 65 Exploded View of TVM 821D 77 Exploded View of Control Panel Assembly 78 Expl
14. NCE Approximately 20 kO LEVEL 0 4 8 or 12 dBm internally selectable factory set to 4 dBm PHASE MATCHING Less than a trace width separation at 20 kHz DISPLAYS Audio may be displayed alone or in any combination with waveform and or vector CONTROL INPUTS 4 Contact closure inputs with common return Dry Contacts CONNECTOR 15 pin Sub D Shared with Audio CONTACTS 30V DC max 9 1A max CONTROLS Each input will cause a system memory to be recalled One input per memory OUTPUTS 1 Dry Contact Closure consisting of 1 Normally Open contact 1 Normally Closed contact 1 Common return CONNECTOR 15 pin Sub D Shared with Audio CONTROLS Contact closure will become energized when an EDH GAMUT or Data error is detected Contact will remain energized for 5 seconds POWER REQUIREMENTS POWER INPUT 115 230V AC 50 60 Hz nominal POWER CONSUMPTION 85 VA maximum MECHANICAL DIMENSIONS Height 5 25 13 34 cm Width 8 5 21 6 cm Depth 17 75 45 1 cm WEIGHT 12 lb 15 45 kg ENVIRONMENTAL OPERATING TEMPERATURE 0 to 50 C STORAGE TEMPERATURE 40 to 75 C HUMIDITY 90 maximum non condensing STANDARD ACCESSORIES Instruction amp Service Manual 15 pin mating D connector Specifications subject to change without notice Installation Instructions POWER REQUIREMENTS The TVM 821D can be operated at either 115V 60 Hz or 230V 50 Hz No external selection has to be made in o
15. ON Theory of Operation conta Sheet 10 U32 is used to latch the lower 8 bits of the address from the multiplexed CPU address data port The programmable device U23 is used to perform the CPU address decoding An 8K capacitor backed up ram U29 and a 128K rom U21 is also used on this PCBA Sheet 11 Front panel and analog board digital interface A bidirect ional data port is used to send and receive data from the TVM 853 board via U35 U36 sends address lines and data strobes to the front panel U37 and U38 provide drive for the control signals which are sent to the TVM 851 board Two signals are received back to U38 from the TVM 851 board analog horizontal and vertical sync Sheet 12 CPU ports U22 is used to access the upper 64K of RAM in 1K sections Address bits 12 through 15 are written by the CPU to this port Port U27 is used to configure the programmable logic chips In addi tion the port for the external error relay is on U27 Port U31 is a micro input port and is used to read the status of the programmable logic chips Sheet 13 General Purpose Inputs Power and Gnd U25 is used to detect external contact closures and report them to the micro Diodes to power and ground in conjunction with 1K input resistors and shunt 0 1 uF capacitors are used for ESD protection A closed contact produces a high signal to the micro 5 volts is used to run the digital logic 12 volts are regulated down to 5 volts for use
16. S The audio level rotary switch SW1 is located on the TVM 851 board accessible on the bottom of the TVM 821D Audio Level Switch Position 0 dBm 0 4 dBm 1 8 dBm 2 12 dBm 3 5x 20mm 50 60Hz TOVA MAX EXT REF SER AL INPUT A REAR VIEW Operating Instructions INPUT SELECTION The INPUT button is used to select which of the video inputs are dis played on the CRT There are three possible selections A only B only and A amp B combined Each press of the INPUT button cycles through the three available modes CHANNEL SELECTION The CHANNEL button is used to select which of the three compo nents is to be displayed as a waveform There are four possible se lections which depend on the format selected In YCbCr format the available channels are Y only Cb only Cr only and Y amp Cb amp Cr com bined In RGB format the available channels are R only G only B only and R amp G amp B combined Each press of the CHANNEL button cycles through the four available modes DISPLAY SELECTION The DISPLAY button is used to select which of the test displays will be viewed on the CRT The number of selections available depends on the status of audio If audio is off the available selections are Waveform WFM only Vector VEC only and WFM amp VEC com bined If audio is on the available selections are WFM only VEC only WFM amp VEC combined and audio only Selecting a
17. TVM 821D Serial Digital Component Monitor Vectorscope Service amp Instruction Manual TWO YEAR LIMITED WARRANTY Videotek Inc warrants that this product is free from defects in materials and workmanship for a period of two years from the date of purchase except for CRTs and LCDs which are warranted for a period of one year During this warranty period Videotek will at its option repair or replace defective products at no charge for the parts or labor Batteries are not covered in the warranty For warranty service or repair this product must be returned to a service facility designated by Videotek in the original packing or its equivalent The purchaser shall insure the product and prepay shipping charges to Videotek and Videotek shall insure the product and pay shipping charges to return the product to the purchaser The foregoing warranty shall not apply to defects or damage resulting from improper or inadequate maintenance by the purchaser connecting the product to incompatible equipment misuses operation outside any environmental specification for the product improper site preparation or maintenance or attempts by personnel other than authorized Videotek representatives to repair or service the product No other warranty is expressed or implied Videotek specifically disclaims the implied warranties of merchantability and fitness for a particular purpose The remedies provided by the foregoing warranty are the purchaser s sole a
18. WFM x5 Use 5 step signal Select V Mag Use 525 line sweep Adjust R226 on the TVM 851 for one step 0 700 mV lines Then set mag offset R222 on the TVM 851 by setting x1 0 mV on bottom line and then adjust trimmer so that x5 is also on the bottom line Select Differential step filter and set differential step position filter trimmer R215 on the TVM 851 for 0 mV on the baseline while in V Mag Using multiburst place scope probe on TP4 on the TVM 850 board CB Adjust for flat response using C45 on the TVM 850 board Move probe to TP3 CR Adjust C48 for flat response Select YCbCr on display Use C139 on the TVM 851 bd and C37 on the TVM 850 bd to achieve waveform flatness Use 10096 color bars Recheck Audio and vector centering In Vector only mode with vect format set to 10096 Set H VEC gain trimmer R224 on the TVM 851 and V VEC gain trimmer R216 on the TVM 851 to center vector dots in boxes Adjust C138 on the TVM 851 bd to adjust the tie lines between the vector boxes to make them straight Connect Audio test box though 821D adapter and set attenuator SW1 to position O 0 dBm and set X audio gain trimmer R228 on the TVM 851 and Y audio gain trimmer R227 on the TVM 851 so that 0 dBm audio input on X and Y will cause the audio line to fall into the center of the audio boxes Change the audio input to 4 8 and 12 dBm while changing SVV1 for each appropriate setting Verify that the audio remains centered in the
19. a is providing data which may be missing proper timing signals c If a known valid input signal is applied to an input but only flat lines are displayed check the input sections of the TVM 850 board CRT display is rolling 1 If external reference in ON and if both 525 and 625 reference LEDs are OFF a Make sure that external analog reference is applied to refer ence input on at rear of unit b Make sure that external analog reference is properly termi nated at the end of the cable c Ensure that the minicoax cables are properly connected to the TVM 851 board d Check that the analog reference is genlocked to the input signal s If external reference is OFF and if both 525 and 625 reference LEDs are OFF a Ensure that input data is 601 serial component data 525 626 b Check the input section for the selected input on the TVM 850 board If viewing two inputs A and B the unit will always sync on INPUT A the B input can roll if not genlocked with the A input CRT display is not starting at beginning of screen Adjust horizontal position control knob If external reference in ON and if both 525 and 625 reference LEDs are OFF a Make sure that external analog reference is applied to refer ence input on at rear of unit b Make sure that external analog reference is properly termi nated at the end of the cable c Check that the analog reference is genlocked to the input signal s Unit may si
20. akes available a negative grid bias measured relative to the cathode of up to 120V The most negative grid voltage ever needed beam cutoff is set by R6 the voltage on R6 wiper becomes the DC reference for the diode clamp circuit Clamp operation then as follows when the intensity signal is blanked the intensity amplifier output goes to about 10V This charges clamp capacitor C17 such that when the intensity is blanked the CRT beam is cut off From there any AC variations the intensity signal are coupled directly through C17 to G1 Since the variations all have to be more positive than blanking level the clamp diodes D3 D4 remain biased off except for during the periodic blanking periods which also refresh the charge on C17 In this manner high speed signals are easily coupled to the intensity grid and the proper DC bias is maintained The focus amplifier similar to the intensity amplifier takes the focus signal and amplifies it to the necessary peak to peak voltage for driving the CRT focus anode The focus signal is a O to 5V signal proportional to the necessary CRT focus voltage A similar scheme to the intensity interface is necessary to couple focus signals to the CRT U2 an inverting op amp circuit with an output pin 7 takes the Theory of Operation cons O to 5V focus signal shipped from the TVM 851 board and changed itto a O to 5V signal suitable to drive focus amplifier U1 switches be tween the focus voltage and groun
21. ct the beam 1 cm on the screen The plates are driven differentially for greater voltage swing and noise immunity The two vertical deflection plates are driven by two identical final amplifiers one being inverted U6 buffers the deflection signal and drives one final amplifier while U4 inverts the deflection signal and drives the other final amplifier Since both final transistor amplifiers are the same only one will be described The final amplifier is made up of Q20 Q19 Q18 Q21 and associated components Essentially it s a classic operational amplifier in the inverting connection with some enhancements for CRT deflection drive Q19 and Q20 are the emitter coupled differential input stage with a tail current of about 7 mA set by R118 Q20 base is the inverting input while Q19 base is the non inverting input grounded for the closed loop inverting connection Although the output stage must be operated from the 100V supply to allow sufficient swing Q20 and Q19 are operated at a Vce of only about 12V emitters stay at 0 7V in this way they can be inexpensive high speed transistors The single ended signal from Q19 collector directly drives the base of Q21 a common emitter amplifier constant current biased by Q18 Large signal positive going output transitions are aided by C36 and C13 which for a short time allow a relatively large base current for Q18 current pass is from 100V through C13 Q18 base C36 R114 to 12V This action incr
22. d which is selected during blanking time The components focus signal is then fed to the focus amplifier made up of Q6 Q7 Q8 Q9 and associated components This amplifier is similar to the previously described intensity amplifier ex cept that it is powered off the 150V supply and the gain is higher R89 R15 R88 26 7 to allow the required greater swing in focus voltage Following the focus amplifier is a clamp circuit based on the same principle as the already described intensity clamp The difference is that the focus anode is biased at about 1200 to 1400V This bias is established by current source Q1 D5 D6 and associated compon ents the actual DC reference for the clamp is trimmed by R7 to center the range of focus control Geometry and Astigmatism circuits R23 provides an adjustable volt age which is buffered by emitter follower Q10 filtered by R27 C8 and sent to the CRT geometry grid GEOM R36 is the adjustment for the astigmatism correction voltage which is buffered by Q14 fil tered by R33 C10 and sent to the CRT astig anode ASTIG Sheet 4 Shows the power supply connection for the board and the graticule light section of the board TVM 853 BOARD Sheet 1 An 8 bit bi directional data with control strobes is used to interface the TVM 853 board with the TVM 850 board The data bus is only driven when the TVM 853 board is addressed by the micro on the TVM 850 board The control strobes for the data bus are t
23. d off SAV EAV Enables viewing of SAV and EAV timing signals while in YCbOr format waveform display FILTER Selects OFF or one of three filters for the waveform display lowpass differential step or bowtie CAL When selected the display changes to a single sweep of an in 10 tering dot VECT FMT When selected the vector display overall amplitude is reduced by 25 to compensate for the increased amplitude of 100 saturated color bars MEMORY Each button press cycles through the four available memory locations In recall mode each memory selected changes the configuration of the unit to match that stored in the memory If all four memories are cycled through the unit will return to it s original state In store mode initiated by pressing the store button first the memory selected will be used to store the current configuration of the unit Each memory selected in the store mode will not change the current configuration of the unit or the configuration stored in the memory until the store button is pressed again If all four memories are cycled through the store mode will be canceled and the configur ation of the unit will be unchanged STORE Enables memory store mode indicated by a flashing SEL light otherwise memory recall mode is active A second press of this button without any memory locations selected will toggle back to recall mode If a memory location was selected while in store mode a second press of thi
24. eases Q21 collector current thereby allowing faster charging of any capacitance on the amplifier output With this enhancement slew rate is dramatically increased in the positive direction and the output stage bias current can be reduced in this case to about 10 mA making possible the low power dissipation and small size of this amplifier Overall gain is set by the ratio of R55 to R56 and is about 12 in this instance R113 pulls about 2 3 mA from the summing node of the amplifier biasing the output to about 25V with no deflection signal This allows for a swing of about 30V at the output Sheet 2 Horizontal clippers identical to the vertical clippers see the previous description The horizontal deflection amp is very similar to the vertical deflection amp which was described in detail previously The important difference is that the horizontal deflection plates must swing over a larger range of voltages than the vertical plates to get sufficient beam deflection for at least two reasons the horizontal dimensions of the screen is larger and the horizontal deflection plates are physically placed in a position where the electron beam is moving faster making it more difficult to deflect fortunately the bandwidth requirement is not as stringent so that the higher voltage transistors required do not have to be as those in the vertical deflection amp Also since the amplifiers are operated from the same 100V supply the outputs can be
25. easily biased to the desired 70V output level The gain of the final amplifiers in the horizontal deflection amplifier is greater than the vertical amps so that approximately equal input signals can deflect the beam horizontally and vertically over the whole face of the CRT In the case of the horizontal final amps the gain is 16 set by the ratio of R38 to R39 for a gain of about 28 Sheet 2 also depicts the CRT socket Sheet 3 Contains the intensity amplifier the focus amplifier the geometry control and the astigmatism control for the CRT The in tensity amplifier accepts DC level and boosts it to the amplitude ne cessary to drive CRT intensity grid G1 Its output is then coupled to the CRT through a clamp circuit which isolates the amplifier from the high voltage bias on the CRT intensity grid The intensity voltage is a 0 to 5V signal proportional to the desired intensity Then at the output pin 1 of U2 an intensity signal appears which ranges from about 0 to 5V with a more negative voltage representing a higher in tensity The blanking signal controls switch U1 to select between the intensity signal and a fixed blanking voltage of about 0 8V The re sultant intensity signal at U1 pin 14 is then ready to be amplified to the levels required by CRT The intensity amplifier is made up of Q2 Q3 Q4 Q5 and associated components It is essentially an op amp configured as an inverting amplifier with a gain given by the ratio R8 R
26. elect vector with no input and hide vector dot behind audio dot with vector Cb centering trimmer R223 on the TVM 851 board and vector Cr centering trimmer R217 on the TVM 851 WFM x1 Select cal and set trimmer R221 on the TVM 851 for 0 to 700 mV Line Rate Move cal signal so that top of cal pulse is on center graticule 350 mV Adjust line rate using trimmer R212 on the TVM 851 so that Cal pulse crosses each major division on timing graticule 0 mV line Mag Select H Mag Using cal signal adjust horizontal mag trimmer R211 on the TVM 851 until the cal pulse crosses the second major division in from both sides on the timing graticule 0 mV line Note Pulse transisitions should be 10 major divis ions apart Mag Centering Adjust horizontal position control in H Mag and trimmer R214 on the TVM 851 in Normal mode so that signal in center of screen does not move when signal is taken in and out of H Mag Two Cell Select A B mode Y channel only paraded input and set 2nd 2H trimmer R225 on the TVM 851 for 1 small timing mark between cells Three Cell Select A input and YCbCr Set 2nd 3H R218 on the TVM 851 and 3rd 3H R219 on the TVM 851 for one small timing mark between channels 24 15 16 17 18 19 20 21 22 Field rate In 3 cells select field sweep and 625 rate input signal Adjust field rate R213 on the TVM 851 for approximately 1 small timing mark between channels Verify 625 LED is on
27. he read and write signals along with the least two significate bits of the TVM 850 micro s address bus U10 is responsible for the address de coding by using A1 and the read and write strobes to determine which of the ICs will be selected If A1 is low the LEDs are addressed If A1 is high the switches are being integrated The front panel switches are broken into two 8 switch banks The micro must write an FEh in order to read switch row 1 Row 1 in cludes the following pushbuttons INPUT REF DISPLAY SWEEP FORMAT SAV FILTER AND CAL The micro must write an FDh in order to read row 2 Row 2 includes the following pushbuttons VIEW CHANNEL AUDIO HMAG VMAG STORE MEMORY and VECT FMT U13 drives the switch data back to the micro on the TVM 850 board Also included on sheet 1 are the vector position pots R50 vertical and R51 horizontal and the power connector Sheet 2 The front panel LEDs are controlled by U11 The micro on the TVM 850 board writes to various registers on U11 which determ ine the state of each LED U11 scans the LED rows and columns so that each LED is pulse when on thereby reducing the total power consumption of the LEDs Resistors on the red LEDs are place holders in case the red LEDs were too bright These resistors are not significant in this design 17 Block Diagram uueg 1061000 Ja ON uu 8 2 pue O N 1109 1
28. ion design Simple operation A B input Overlay mode for easy system timing A B input Parade mode for level comparison LED alarms for EDH Gamut and Data errors Input EQ display for quick verification of signal integrity Analog audio input with X Y display for gain and phase measurement RGB or Y Cb Cr display 525 625 operation Auto sensing Four memories for fast recall of set ups GPI input for memory recall Looping external analog reference input GPI output for alarm indication Specifications VIDEO INPUTS Two 270 Mb s 4 2 2 serial digital video CONNECTORS BNC female IMPEDANCE 75 O nominal passive loop through RETURN LOSS gt 18 dB to 270 MHz LEVEL 800 mV p p 10 EQUALIZATION Automatic equalization for a minimum of 200m of Belden 8281 cable ANALOG REFERENCE INPUT Composite video or blackburst CONNECTORS BNC female IMPEDANCE 75 O nominal passive loop through RETURN LOSS gt 40 dB to 5 MHz SYNC LEVEL 143 mV to 600 mV SYNCHRONIZATION REQUIREMENTS INTERNAL REFERENCE Derived from serial A or serial B data or free running internal source EXTERNAL REFERENCE External sync will synchronize sweeps VERTICAL DEFLECTION SYSTEM FLAT Y channel to 5 MHz lt 2 0 2 dB Color difference channels to 2 5 MHz lt 2 0 2 dB LOW PASS 3 dB attenuation at 1 MHz Low pass response 10 kHz within 1 1 dB of Flat response DIFFERENTIATED STEP For a non modulated 5 step input w
29. ith each step being 140 mV 1 the spikes produced by the filter are 500 to 700 mV The difference between amplitudes will be less than 2 of the first Spike s amplitude TRANSIENT RESPONSE Less than 5 mV of preshoot and or overshoot at full scale Flat mode using sin pulse bar signal PULSE TO BAR RANGE 0 99 1 to 1 01 1 TILT FIELD RATE SQUARE WAVE OR VERTICAL WINDOW OR 25 uS PULSE SIGNAL 1 VERTICAL MAGNIFICATION x1 or x5 HORIZONTAL DEFLECTION SYSTEM FIELD RATE TIMEBASE Equal to x1 x2 or x3 of the field rate of applied video or external reference User selected Parade modes LINE RATE TIMEBASE Equal to x1 x2 or x3 of the H line rate of applied video or external reference User selected Parade modes SWEEP MAGNIFICATION x1 or x10 TIMING ACCURACY 1H H Mag 0 5 us div 2 2H H Mag 1 us div 2 of 1H Mag 3H H Mag 1 5 us div 2 of 1H Mag LINEARITY 2 or less over complete horizontal position range ex cluding first and last major division CALIBRATOR WAVEFORM MODE FREQUENCY 100 kHz to 0 1 kHz synchro nizes in H sweep modes providing reference for sweep and magnifier calibration AMPLITUDE 700 mV 0 5 VECTOR MODE Provides vector centering dot MULTIPLE DISPLAY MODE MEASUREMENT ACCURACY WAVEFORM OVERLAYS H MAG 100 ns Relative 1 5 mV Relative VECTOR OVERLAYS 1 5 mV Relative AUDIO INPUTS Balanced analog audio AC coupled CONNECTOR 15 pin Sub D IMPEDA
30. layed on CRT Selected input is not present Selected input is too attenuated to be equalized Selected input is not 601 serial component video 525 625 Check the input section of the TVM 850 board The serial input receivers may need to be adjusted as described in the calibration procedure oO NS Waveform amplitudes are not correct 1 Ensure integrity of input signal 2 Unit may need to be calibrated The majority of the calibrations are accomplished on the TVM 851 PCB 3 High voltage supply may be damaged 100V 26 Interconnection Diagram A ddns 9mod UBIH sqouy 01409 514617 ejnoneas gLSS INAL 4238 NAL 9NO Nol A ddns 198mod BE10A NO Uld 91 Aejdsig 9ueg 14014 S8 INA L Bojeuy VISS INAL SINO Buiss Soid eubis jeubia 0S8 INA L 27 NOTES 28 Addendum
31. lown replace with fuse of same type 4 Check low voltage power supply The fuse on this supply has been bypassed to ensure only the fuse on the outside of the unit will need to be replaced a Check that AC switch on front panel is allowing AC to the low voltage power supply Check for 45V 12V from this supply Disconnect the three DC power cables from the supply d Recheck the 5V 12V from this supply If one or more of the voltage from this supply are missing with no load the power supply is damaged i Reconnect each of the power cables one at a time Connect the power to the TVM 850 board first the TVM 851 board next and the power cable to the high voltage block last As each is reconnected monitor the 5V 12V from the supplies ii If one of the cables causes the loss of a voltage the board or high voltage block may be damaged Om Front LEDs on no CRT display Make sure intensity is not turned down 1 Press CAL button If vector centering dot appears in middle of CRT use the H POS and V POS knobs to return calibration waveform to its proper position on screen 2 Make sure that low voltage supply 12V output is operating pro perly 3 WITH UNIT OFF ensure that all cables inside the unit between the boards are properly connected Ensure that CRT anode cap is on the tube and that the tube wiring harness is properly con nected 4 Test points on the TVM 850 board can be used to monitor the waveform and
32. mply be showing the timing difference between the serial data and the analog reference If INPUT A and INPUT B are selected the CRT will use the A in put as the reference external reference OFF The B input will be display the timing difference between the two inputs Unit may need to be calibrated High voltage power supply 100V may be damaged Troubleshooting Procedure conta Audio levels too high or too low 1 The unit is factory set for a nominal audio input on the audio left and right of 4 dBm referenced to a 6000 load Switch SW1 is label audio attenuator and may be set for a O dBm 4 dBm 8 dBm or a 412 dBm reference 2 Audio amplitude may need to be adjusted on the TVM 852 board 3 Unit may need to be calibrated CRT displays only noise 1 If the EQ lights for the selected input are at MAX a Input may be too attenuated for the scope to lock onto gt 200m of Belden 8281 cable Input is not 601 serial digital video 525 625 Input cable is not properly terminated Check the input section on the TVM 850 PCB Audio only mode may be selected High voltage power supply may be damaged ARON Reference LEDs are both off 1 If external reference is selected check that an analog reference input is properly connected the to the reference input 2 Selected input is not present in single input mode 3 INPUT Ais not present in A B mode Data error LED flashes continuously and flat lines are disp
33. nd exclusive remedies Videotek shall not be liable for any direct indirect special incidental or consequential damages whether based on contract tort or otherwise Printed May 2006 Item 4061711 Rev B Copyright O 1997 2006 by Videotek Inc All rights reserved Contents of this publication may not be reproduced in any form without permission of Videotek Inc This instrument in whole or in part may be protected by one or more US or foreign patents or patent applications Specifications subject to change without notice Videotek and the Videotek logo are registered trademarks of Videotek Inc Blank Page OPERATOR S SAFETY SUMMARY Refer all servicing to qualified service personnel To maintain and to ensure safe operation observe the following instructions symbols and precautions 1 2 3 When the unit is to be permanently cabled first connect protective ground conductor before making any other connections Built in units should only be operated when properly fitted into the system For permanently cabled units without built in fuses automatic switches or similar protective facilities the AC supply line shall be fitted with fuses rated to the units Before switching on the unit ensure that the operating voltage set at the unit matches the line voltage If a different operating voltage is to be set use a fuse with appropriate rating Units of Protection Class with disconnectable AC supply cable and plug may
34. ntrols the sharpness of the CRT beam H POS Knob which controls the horizontal position of the wave form display V POS Knob which controls the vertical position of the waveform display VECTOR H Trimpot which controls the horizontal position of the vector display VECTOR V Trimpot which controls the vertical position of the vector display RIGHT CONTROL PANEL BUTTONS INPUT Selects one or both of the digital video inputs A B or A amp B VIEW Selects inputs overlaid or paraded in waveform display REF Selects external reference nominal reference is selected input or input A when in A amp B mode CHANNEL Selects one or all three of the video components Y Cb Cr or Y amp Cb amp Cr When in RGB mode the selectable components are R G BorR amp G amp B DISPLAY Selects display as waveform vector or waveform amp vector When in audio mode both waveform and vector may be dis abled resulting in an audio only display AUDIO When selected audio is added to any of the display modes In addition an audio only display may be achieved by disabling both waveform and vector using the display button SWEEP Selects between a line rate and a field rate waveform sweep HMAG Toggles waveform horizontal x10 magnification on and off FORMAT Selects between YCbCr native component format and RGB transcoded component format waveform displays VMAG Toggles waveform vertical x5 magnification on an
35. oded View of CRT Ass y amp Connector Panel Ass y 79 Dimension Drawing of Standard Case SSC 1 80 Dimension Drawing of Double Rackmount Case DRC 1 81 Dimension Drawing of Portable Case PTC 1 82 A e E ha RUE een 83 Features With 12 bit processing the technically advanced TVM 821D serial digital waveform monitor vectorscope for 601 video brings the most commonly needed functions within quick easy and affordable reach With elegance and accuracy the TVM 821D was developed with the operator in mind incorporating a button per function concept Intelligent design philosophy makes the operation of the TVM 821D intuitively obvious Unique features include an array of LEDs to continually advise the operator of the input signal strength preventing the possibility of system crashes due to weak signals A second unique feature is the ability to observe two digital inputs simultaneously An A and B display either in parade or overlay makes routine tasks such as synchronizing timing and level setting easy to perform Other functions include LED alarms to alert the operator of EDH EAV and SAV data problems Add this to Videotek s long history of making high quality test instruments the TVM 821D is the perfect test solution for editing production and post production broadcast and remote vehicles Two component serial digital inputs Button and knob per funct
36. offset by the front panel vector vertical position control U25 and amplified by U15 The Cb component VCB is DC restored by U26 and U13 The output of the DC restorer enters a 4x1 switch U14 This switch selects be tween the Cb component and the audio horizontal component The output of the switch enters a fixed delay all pass filter U26 The out put of U26 is offset by the front panel vector horizontal position control U26 and amplified by U27 The output of U27 is connected to a double isolated switch U34 This switch selects between the output of U34 and the waveform horizontal deflection ramp The output of the switch is amplified by U44 before entering the CRT deflection board TVM 852 Sheet 6 The circuit on this sheet is a precision ramp generator for the horizontal deflection of the waveform display Q7 and U5 forma constant current capacitor charging circuit which provides a linear ramp U6 switches the charging current to the proper capacitor for the selected sweep C8 is selected for line sweep and C137 is selected for field sweep Q3 and Q8 reset the ramp at the end of the sweep by discharging the associated capacitors In addition to U6 selecting line or field sweep U4 selects different ramp rates depending on what display mode is selected If all three components are to be displayed in a paraded sweep the ramp charging rate has to be three times as long as that needed for a single line sweep R212 and R213 are used to calibrate the
37. on resulting in a horizontal sync signal at TL6 The composite sync is low pass filtered by U32 and latched by U19 creating vertical sync Sheet 3 This sheet illustrates the interconnections to the waveform and vector position controls CN9 connects the vector vertical and horizontal position controls CN11 connects the waveform vertical and horizontal position controls to the TVM 851 board Sheet 4 The graticule intensity control R64 is connected via CN11 to the graticule lamp driving circuit The variable voltage created by R64 is amplified by U1 Q4 Q5 and Q6 This circuit controls the amount of current flowing through the graticule lamps attached to CN14 The beam intensity control R29 and the focus control R98 are buf fered by U35 before entering the CRT deflection board In addition a small amount of intensity voltage is added into the focus path via R167 in order to maintain the focus over the full intensity range Q10 and Q11 buffer the trace rotation control R229 from the trace rotation coil connected to CN12 15 Sheet 5 The Cr component VCR is connected to a DC restorer comprised of U25 and U13 The output of the DC restorer is con nected to a 4x1 switch U14 This switch selects between the Cr com ponent and the audio vertical component The output of the switch enters an all pass filter which is used to adjust the delay of this signal to match the timing of the horizontal deflection path The output of the all pass is
38. only be operated from a power socket with protective ground contact a The protective ground connection should not be made ineffective by an extension cable b Any breaking of the protective ground conductor within or outside of the unit or loosening of the pro tective ground connection may cause the unit to become electrically hazardous c The protective ground conductor shall not be interrupted intentionally Before opening the unit isolate it from the AC supply a Adjustments and replacement of parts as well as maintenance and repair should be carried out only by qualified personnel b Observe safety regulations and rules for the prevention of accidents c Use only original parts for replacing parts relevant to safety e g power on off switches power trans formers or fuses Operator replaceable fuses may be hazardous live When replacing fuse turn unit off by isolating it from the AC supply Also observe the additional safety instructions specified in this manual Explanation of Symbols Used I 6 P gt Read Operator s Handbook and Service Manual observe the safety symbols used Caution shock hazard Protective ground connection Unit ground Eguipotentiality Ground Use of Cleaning Solvents Cleaning of the eguipment with isopropyl alcohol or similar solvents may cause degradation of labels Use caution when cleaning so that labels are not removed BLANK PAGE Table of Contents Features ae er QUA
39. ows the storage and retrieval of four complete sets of front panel configurations This includes all of the buttons but does not include any of the knobs or trimmers The configuration memories are loaded with default values at the factory The default configuration is as follows Input A only Internal reference WFM only Line sweep Format YCbCr Parade of channels Y Cb and Cr The contents of all four memories may be changed to that of any front panel configuration The memories are capacitively backed to pre serve the contents in the case of a power failure To store a front panel configuration perform the following 1 Make the desired front panel selections to be stored in the memory 2 Press the STORE button the SEL light should be flashing 3 Press the MEMORY button repeatedly until the desired memory location light is flashing 4 Pressthe STORE button again the SEL light should go out and the MEMORY light should stop blinking MEMORY PRESET RECALL To recall a front panel configuration from a memory location 1 Verify unit is not in store mode SEL light is not flashing If the SEL light is flashing cancel the store mode by pressing the MEMORY button repeatedly until the SEL light shuts off Note if the unit is in store mode and a memory location is selected pressing the STORE button will overwrite the selected memory lo cation Operating Instructions conta 2 Press the MEMORY button repeatedly until the desi
40. queujsn pe 101994 001 SZ preog Dojeuy jeubig tuonoej es uuoJeAeM ua OL 10413 1nujec 7 pue UOISISAUOD eoeds 10102 xg q 19 _ 7 Bojeuy o xz Aq eui seop a5 jeubiq WAM YOIUM ejqeuureJ6oJ4g a ejodua u 1821 XNN 90 m t 99019 uonoejeq 5 1043 ejeq a w Hd3 pue X UOonoenx3 r xnueg Sur xniy 921A9q ajqewweiboldg lezijeueseq HAOU O3 eiqe5 V leues 19 Block Diagram for TVM 851 Board 191 JUU 102 uonejoH 2981 OL uonelou s oy duy ysuaju pleog 298 NAL OL uesa pue sno04 e nomneJc Jedduis pJeog 0S8 INA L 01 SUAS ou S J EJUOZIJOH Bojeuy p eog 258 WAL 01 eubis uonoejeq jejuozuoH Bojeuy peog 298 1 01 eubis uonoejeq oaa Dojeuy eubis eouoij9jou doo Bojeuy uonoeles EJUOZIJOH eua uonosjeg uonoejeq 041400 40199195 Pa OSS WAL W01 191114 sjeufis jeu q 3 Jeuduny UOHEOlU ELN 10e 495 Pg 0S8 INA L WO deems speuBis Buiu dd PME 1206119 jeyuozuoH EJUOZUOH UIe5 uonoejes yndu Joyenus y oipny x olpny ule uono l s 5 J0198A OIPNY uled Y 9101594 JOJ99 A BJUOZIJO ope eJUOZUOH E1UOZIJOH Od 4019 A 80 go urec uonosjes indu 1ojenueny oipny A olpny ueg u01 99 9S 1 prece 5 UlED 8 810 594 JOJ99A eonJeA Renas OQ 109A HO Bojeuy uo
41. rder to change the in put voltage If it becomes necessary to replace the fuse make sure to adhere to the proper fuse value RACK MOUNTING The metal cabinet SSC 1 for the TVM 821D provides the proper electrical environment for the instrument limits the handling dam age and reduces dust collection Two 8 32 screws are provided to secure the unit into the metal cabinet they are installed in the rear of the unit COOLING OF THE TVM 821D The TVM 821D is cooled by an exhaust fan at the rear of the unit For proper air circulation a minimum of 1 75 inches should be maintained above and below the unit Care should be taken not to block the exhaust fan at the rear of the unit CUSTOM INSTALLATION All installations must provide adequate ventilation and mechanical protection Top openings should not exceed 0 15 inches in diame ter Other openings should not exceed 0 45 inches in diameter pro vided the circuits are at least 0 6 inches from the surface of the en closure All conductive parts must be connected to the frame or ground BOTTOM OF UNIT TVM 851 PC BOARD AUDIO REF LEVEL SW1 TRACE ROTATION POT R229 AUDIO LEVEL SELECTION An internal rotary switch is provided to select the nominal audio in put level This selection will provide the required attenuation for the audio display Factory setting is 4 dBm Adjust audio reference level rotary switch SW1 located on bottom of TVM 821D see diagram below
42. red memory location is selected Each press of the MEMORY button will recall a sequential memory location If the MEMORY button is pressed after location number four was selected memory recall will be disabled and the front panel will return to it s original state 3 If any other button is pressed after a memory location has been recalled memory recall mode will be canceled because the front panel will no longer match that stored in the memory location POWER UP RESET If the CAL button is held in while the power switch is cycled on the unit will execute a system reset forcing the front panel and all memory locations to the factory default state Input A only Internal reference WFM only Line sweep Format YCbCr Parade of channels Y Cb and Cr TIMING MEASUREMENTS using EAV SAV markers as illustrated below Start of Active Video SAV and End of Active Video EAV are timing signals which occur in each line of 601 video 525 625 line The sig nal consist of 4 bytes each and occur just before and after the samples of active video These timing signals are normally not shown on the CRT when lines of video are displayed EAV SAV off How ever the EAV and SAV markers are useful when determining how well the active video is centered between these markers In line rate sweeps by pressing the EAV SAV button to enable this function the SAV marker will appear as a large spike at the beginning of each line of video The EAV marker be a
43. rformance Check conta MEMORY CHECK TABLE ue Meme Momo ssy T T T n T 23 Calibration Procedure EQUIPMENT NEEDED Dual Channel 100 MHz Scope DMM Digital Video Generator or 601 Video Source Belden 8281 Cable Simulator SIGNALS NEEDED 100 color bars 525 and 625 75 color bars 525 and 625 Oversized Ramp Pathological Matrix Multiburst CONNECTIONS Digital Video Cable to Input A Cable between Input A and Input B Terminate Input B Analog Blackburst from Digital Generator to REF IN Terminate REF IN loop through Cable from Audio 15 pin connector to Sub D connector Power Cable TEST PROCEDURE 10 11 18 14 Set Geometry Brown wire to CRT to 32V using R23 on the TVM 852 board Rear Blue pot on Deflection Board Focus Master Control Set front control to center and adjust pot R7 on the TVM 852 board on the BNC side for proper focus of display Astigmatism This interacts with the focus adjustment Blue pot R36 on the TVM 852 board Intensity cut off Viewing vector dot only no signal set front panel intensity to minimum Adjust cutoff with pot R6 on the TVM 852 board Intensity limit Set maximum brightness on front of unit and ad just pot R230 on the TVM 851 board analog board Trace rotation Using trimmer R229 on the TVM 851 board next to intensity Select Audio with no input Using front panel vector position con trols center the audio dot S
44. s button will store the current configuration of the unit in the selected memory All modes are activated by independent button presses there are no timed button press sequences required If a selection is made which does not pertain to the current display the selection will still be made however the results might not be seen until the corresponding display is selected POWER Master power on off switch Front amp Back Panel Controls conta INDICATORS LEDs AT BOTTOM OF FRONT PANEL EQ A amp B Bar graphs continuously indicate the equalization compen sation required for both video inputs The minimum and maximum points represent the limits of the compensation range ERROR EDH Indicates the presence and status of the Error Detection and Handling EDH Green represents a valid EDH calculation and red represents an EDH error A blank indicator represents no EDH de tected GAMUT Indicates a video signal excursion beyond the RGB limits DATA Indicates missing End of Active Video EAV and or Start of Active Video SAV Timing Reference Signals TRS from the se lected digital video input All error indicators will remain active a minimum of one second after the occurrence of an error REFERENCE 525 625 Indicates the standard of the reference video 525 lines or 625 lines Y Cb Cr RGB FORMATS While in Y Cb Cr format the following applies 1 Waveform displays video inputs in the native 601 YCbCr format
45. t serial digital video 4 2 2 streams to analog component video In addition this board also houses the microprocessor used to control the TVM 821D 2 TVM 851A contains analog waveform filters sweep generation circuitry and audio processing 3 TVM 851B front panel control board Controls intensity graticule focus horizontal and vertical position 4 TVM 852A this board contains CRT detection amplifier TVM 852B graticule light board 6 TVM 853 board is the front panel select board and contains the contact surfaces for the front panel rubber keys In addition this board contains the front panel LEDs and the vertical and hori zontal vector position pots a The following is a more detailed description of each circuit board s functions The sheet number s described under each board corre sponds with the sheet number in the title block of the schematic for that board The schematic section starts on page 30 TVM 850 BOARD Sheet 1 amp 2 Both of these schematic pages serve the same func tion Sheet 1 converts digital serial input A to parallel data 10 bit and extracts the parallel clock Sheet 2 performs the same function for input B U10 and U24 receive the loop through serial digital data and extract the 270 MHz clock Differential clock and data are output from U10 and U24 to U8 and U26 U8 and U26 deserialize the data and output 10 bits of parallel data and a 27 MHz clock U19 is used to amplify the signal s
46. ther The audio pattern should pass through the 10 audio mark on the CRT Return to video mode by pressing the DISPLAY and AUDIO buttons 22 Missing bits check a b f Change INPUT to A Change input signal to oversized ramps Using HMAG and VMAG as needed verify that the ramp is smooth and contains no gaps or sudden unusual transitions Change INPUT to B Using HMAG and VMAG as needed verify that the ramp is smooth and contains no gaps or sudden unusual transitions Repeat test for INPUT B Memory storage check a d Using the table below store the following into each memory by setting up the scope pressing the store button selecting a memory location and pressing the store button again Power down and then power up unit Recall each memory by pressing the MEMORY and ensure that states in table are maintained Using external switches on the audio 821D adapter board re call each memory by pressing corresponding pushbutton Gamut error and relay check a b d Recall Memory 1 Apply 100 color bars to unit Verify that GAMUT error light is off Using ohm meter across gamut test point unsure that resist ance of N O contacts is gt 1 MO and that N C contacts are 1 Apply oversized ramps to unit Verify that GAMUT error light is on Using ohm meter across gamut test point ensure that resist ance of N O contacts is 1 O and that N C contacts are gt 1 MO Pe
47. trength indicator from U10 and U24 and buffer the signals to the micros A D converter This signal is used to drive the unit s front panel equalization LEDs Sheet 3 Both sets of 10 bit parallel data from the deserializers U8 and U26 go to U20 U20 is a programmable logic device PLD This device is programmed serially by the microprocessor at power up The code for this device is a stored in the units ROM U21 The pixel clocks from U8 and U26 are multiplexed via U14 and U15 along with an internal 27 MHz crystal clock and are applied to the programmable device Each individual pixel clock is also sent into the programmable devices for internal reference timing The PLD device U20 performs the following functions 1 Extracts reference timing for input A input B or external refer ence or a free running internal generator 2 Scans each set of parallel pixel data to determine the beginning and end of active video the occurrence of horizontal sync and the occurrence of vertical sync 3 Demultiplexes the data into its component forms Y Cb and Cr Checks the input A or B not both data for EDH and Data errors 5 Provides all timing for real time control of beam and analog switching This timing is derived from either input A input B the external analog reference or is generated as a free running source inside this logic device gt 14 Sheet 4 Cb and Cr Data from U20 is sent to Interpolators U3 and U4 The
48. udio off while viewing audio only will return the display to WFM only Each press of the DISPLAY button cycles through the available modes AUDIO SELECTION The AUDIO button is used the activate the audio lissajous trace Se lecting audio ON will add the audio pattern to any of the displays se lected by the DISPLAY button In addition while audio is ON an audio only mode is added to the available display modes accessible by the DISPLAY button Each press of the AUDIO button will toggle audio ON and OFF VIEW SELECTION The VIEW button is used to select between paraded and overlaid waveforms Parade means waveforms displayed next to each other overlay means waveforms displayed overtop of each other The effect of the VIEW button is dependent on INPUT and CHANNEL selections and pertains only to the waveform display Each press of the VIEW button toggles between parade PAR and overlay OVR VIEWS While only a single input is selected A or B the following applies 1 If only a single channel is selected a The VIEW button has no effect on the appearance since there is only one waveform to display 2 If all three channels are selected a n parade vievv the channels appear next to each other b n overlay vievv the channels appear overtop of each other While both inputs are selected A amp B the following applies 1 If only one channel is selected a n parade vievv the inputs appear next to each other b n
49. urrence of data errors Theory of Operation cons TVM 852 BOARD Sheet 1 Vertical deflection amplifier The vertical signal enters the board on CN4 pin 6 The signal passes though the vertical clipper consisting of Q23 Q24 Q32 and Q31 and their associated capacitors and resistors The vertical clipper limits the deflection signals to about 2 5V prior to the final vertical amplifier The purpose of the vertical clipper is to prevent the vertical deflection amplifier from entering saturation when driven by large input signals This helps to increase the recovery time when signals beyond the scope viewing area are applied to the input The clipper is required because the vertical deflection amplifier takes a relatively long time to recover from an overdriven condition Clipping of negative peaks is accomplished by Q23 and Q24 the threshold is set by R112 R58 D14 When the deflection signal starts to go more negative than about 2 5V Q24 starts to turn on pulling base current through Q23 thereby turning Q23 on and sourcing current to the junction of R120 and R126 to keep the voltage at that point from going more negative Similar action is performed on positive peaks by Q32 Q31 The vertical deflection amp takes the deflection signal from the clipper and amplifies it to peak to peak voltages suitable to deflect the CRT electron beam via the vertical deflection plates Typically it takes about 5 volts across the deflection plates to defle
50. vector analog outputs The signals may be traced through the TVM 851 board 7 IS NOT RECOMMENDED THAT THE TVM 852 BOARD BE PROBED AS HIGH VOLTAGES gt 2000V ARE PRESENT ON THIS PCB 5 High voltage power supply may be damaged CRT display on no LEDs Cycle power to unit 1 A CPU cold start can be executed by holding the CAL button while power is applied to unit Note cold starting a unit will clear the user memories 2 Ensure that all cables are connected to the front panel PCB TVM 853 This board uses on 5V to operate It communi cates to the TVM 850 board s micro via a 16 pin ribbon cable Check that the socketed ICs on the TVM 850 board are firmly seated in their sockets Serial input connected to INPUT A and or INPUT B but CRT display only flat lines Ensure that the proper input is selected on the front panel 1 If data error light is flashing and the EQ lights for the selected in put are at maximum a Check to ensure the cable BNC at the rear of the unit is pro perly connected to one of the serial inputs i Check that the signal generation equipment is powered on and connected correctly 25 il Ensure that the looping input is properly terminated at the end of the cable b If data error light is flashing and the EQ lights for the select ed input are not at maximum i Check to ensure that digital data is 601 video This scope will only display 601 serial component data 525 625 il Source of 601 dat
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