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Protection Circuit 2

The remainder of the protection sensing circuitry on the G board is shown
in this diagram. It monitors the following items:

¨

+5V OCP

¨

+135V OCP

¨

+5V OVP

¨

+135V OVP

The output of these four sensing circuits triggers two stages:

1. The latch circuit on the G board to shut down the TV.
2. The Main Micro for a visual indication of the section that caused the

protection.

+5V OCP

The +5 volts from Converter 2 is monitored by this circuit for excessive
current. The +5V from D5041 passes through both R5038 and R5076
connected in parallel. If the voltage dropped by these resistors exceeds
0.6Vdc, Q5019 conducts and raises the voltage at its collector. This volt-
age turns on Q5018, which turns on Q5017. A high is output Q5017’s
collector that takes two paths:

¨

Through D5047 to the protect latch, shutting off the TV; as well as

¨

Through D5046 to the Main Micro IC3251/pin 43 to blink the standby
light six times, pause and repeat.

Q 5 0 1 9 N o r m a l D C V o lta g e s

E m it te r

B a s e

C o lle c t o r

+ 5 . 2 3 V

+ 5 . 1 4 V

0 V

Excessive current means that there is a shorted part on a board powered
by the +5V line. In searching for the load, never unplug an M board con-
nector when there is +135V present on the G board or the G board’s H.
Driver Q4011 and PWM Driver Q4003 will short.

+5V OVP

The +5 volts is also monitored for excessive voltage by zener D5042. If
the +5 volt line rises above the 6.2V zener voltage, a voltage is applied to

amplifier Q5018 and Q5017 to shut down the TV and blink the light six
times. A higher voltage at the +5V line means that Converter 2 is not
regulating. Measure the +5V line with a peak hold DVM to verify the over
voltage.

135V OCP

The +135V OCP circuit is similar to the +5V OCP circuit. The +135 volts
from Converter 1 is monitored by this circuit for excessive current. The
+135V from D5015 passes through both R5026 and R5101. If the voltage
dropped by these resistors exceeds 0.6Vdc, Q5009 conducts and raises
the voltage at its collector. This voltage turns on Q5020, which turns on
Q5016. A high is output Q5016’s collector that takes two paths:

¨

Through D5022 to the protect latch, shutting off the TV

¨

Through D5013 to the Main Micro IC3251/pin 44 to blink the standby
light two times, pause and repeat

Excessive current demand on the +135V line can be caused by: Horizon-
tal Output Transistor Q4018, FBT 7001, Pincushion Output MOSFET
Q4027, or Dynamic focus correction Q7009 and Q7012.

135V OVP

These parts forming the sensing circuit perform the +135V excessive /
over voltage protection (OVP):

+ 1 3 5 V O V P P a r ts

D e v ic e

N o r m a l s ta t e

P u r p o s e

D 5 0 1 9 – 2 4 v o lt
z e n e r

N o c o n d u c t io n

W a t c h e s t h e + 1 3 5 V lin e v o lt a g e
d iv id e d b y R 5 0 2 0 & R 5 0 2 8 .

Q 5 0 0 8 – N P N

O F F

A m p lif ie s t h e in p u t ( s w )

Q 5 0 0 3 - P N P

O F F

A m p lif ie s t h e in p u t ( s w )

An exc135V B+ breaks over the zener and turns on both Q5008
and Q5003 transistors on to apply voltage:

¨

Through D5017 to the protect latch, shutting off the TV; as well as

¨

Through D5048 to the Main Micro IC3251/pin 45 to blink the standby
light three times.

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Содержание DTV-01

Страница 1: ...S Training Manual Circuit Description and Troubleshooting Course DTV 01 High Definition Television ...

Страница 2: ...ideo Process D 47 On Screen Display 49 Video Process E 51 Screen Voltage Control 53 POWER SUPPLY Power Supply Block 55 Standby Power 53 Converter 2 61 Overall Protection Block 67 D Board Protection Block 71 Protection Circuit 1 73 Protection Circuit 2 75 Protection Circuit 3 77 Protection Circuit 4 81 DEFLECTION Vertical Deflection 85 Horizontal Deflection Block 89 Horizontal Drive 91 Horizontal D...

Страница 3: ...Dynamic Focus 1 B Mfg 117 Dynamic Focus 2 Location 121 Dynamic Quadrapole Focus 125 Appendix Set Back Box i Picture Size Modes iii Board Replacement iv Service Mode Display vi ...

Страница 4: ...her definition HD transmission can be transmitted only in the digital DTV mode SDTV or SD Standard definition is the current 525 lines of resolution transmitted but only 480 of those lines are viewable SD can be sent as an NTSC analog or digital DTV transmission HDTV or HD A high definition transmission contains 720 or more horizontal lines HD is transmitted only in a digital format DTV A digital ...

Страница 5: ...tments for convergence video level size and white balance or positioning 1 The numerous service mode registers are usually grouped by ICs for easy access Use the remote s 2 and 5 button to change IC groups Then you can move from register to register with the 1 and 4 but tons 2 Each register that controls the picture s size deflection and position on pages 45 47 of the service manual has seven sets...

Страница 6: ...ponents called R Y B Y and G Y As it works out we can mathematically calculate the 4th component G Y from the others Therefore we only require 3 components for Video Y R Y and B Y Y R Y B Y G Y Each sample we take of the video is represented by an 8 bit digital word which translates to 28 or 256 different levels of each component There fore each pixel is made up of 3 components which can represent...

Страница 7: ...taken of Y as they are of R Y and B Y Time Signal 4 2 2 Since the eye is less perceptive to color changes than to Luminance significant reduction of data can be accomplished in the Sampling process if we sample the color components R Y and B Y half as much as the Luminance component Y The result is a 1 3 reduction or a bandwidth of 166Mbits sec Video sampled using this technique is represented by ...

Страница 8: ...me the very fine picture details consist of high frequency information which are basically fast changing Luminance and Color content In contrast low frequency information are slow changing Luminance and Color content The high frequency information consumes the most data real estate and is where we focus to compress in this next stage The process of eliminating the imperceptible information is call...

Страница 9: ... first frame could be stored as the reference or non changing por tions while remaining frames carry the lip motion information This would eliminate the need to store several full frames Frames using Temporal redundancy which predict information based on preceding frames are called Inter Frames or Motion predicted Images Predictive Motion Encoding The next step in the MPEG process is termed Predic...

Страница 10: ...ack at previous I or P Pic Information passed to generate P Picture B Pictures The B Pictures have Bi directional dependency and are called Bi Directional Predicted Images The B Picture is also a predicted Image but it is based on prior I or P Pictures and preceding P Pictures B Pictures are typically made up of motion information and carry the least amount of data I or P Picture B Pictures Predic...

Страница 11: ...the I Picture 2 In between the I and first P picture several B Pictures are gener ated as necessary to convey motion information from the I to the first P Picture For this reason B Pictures are dependent on past and future pictures 3 Then the process repeats with the generation of second P Picture which is now based on the first P picture And so on I B B P B B P GOP Time I Hoffman Encoding The las...

Страница 12: ...es data to about 1 40 on average while MPEG I compresses data to about 1 140 on average Therefore 250Mbit s are reduced to 6 25Mbits s on average using MPEG II MPEG II uses a variable rate compression while MPEG I uses a fixed rate 350 x 240 84 000 pixels 720 x 480 350 000 pixels MPEG I represents 84 000 350 000 25 of MPEG II MPEG II additional information MPEG II is a broad standard which encompa...

Страница 13: ...t rate the system might fall short on the football scene And it would definitely be wasting bits on the restaurant scene DVD Video accommodates both scenes by varying the bit rate In fact the maximum bit rate is 9 8 megabits per second which is nearly three times as high as the average rate If DVD used a fixed rate it would have to be at least 7 Mbps to maintain picture quality At that rate total ...

Страница 14: ...ilm frames into video fields However video requires 30 frames or 60 fields and Film is 24 Telecine performs this process by converting 12 film frames to 24 fields 2 Fields Film Frame and another 12 film frames to 36 fields 3 Fields Film Frame It is kept seamless by converting one Film Frame to 2 Fields and the next one to 3 This cycle is repeated 2 3 2 3 until the 60 fields have been completed Thi...

Страница 15: ...18 NOTES ...

Страница 16: ...N Standby light ON TV OFF 1 3 Amps 120Vac TV OFF A Master Power OFF pressed 2 relays clicks TV sound mutes Picture goes dark All lights out TV OFF B Remote power OFF pressed 2 relays clicks TV sound mutes Picture goes dark Standby light comes ON TV Operation with NO Inputs connected Selection Access Step Sounds Visual Conditions Video input Press TV Video button until video 1 2 or 3 appear on the ...

Страница 17: ... 4 It takes about 1 min to scan through all the cable stations At the end it will select the lowest number active cable station High Definition TV Connect an UHF antenna to the DTV Receiver external set back box and the receiver to the rear of the TV using the supplied multi pin I O cable 1 Power ON 2 Use the remote TV Video button to select TV 3 The remote ANT button toggles between VHF UHF and c...

Страница 18: ...m waveform is the luminance signal containing the H sync pulse below the base line S Video Input The S input refers to Separate Video inputs consisting of independent luminance Y and chroma C signals and a shield wire for each They are input using a 5 pin standard connector The fifth pin serves to close a switch in the jack that identifies the presence of the S video plug The S Video signal is sel...

Страница 19: ...ENU TV CABLE VHF UHF ANALOG TV INPUT Y PB PR L R S VIDEO VIDEO HD AUDIO OUT VAR FIX L MONO R CONTROL S IN OUT DVD 1 3 FOR USE WITH HD 1080 INPUT ONLY HD L MONO AUDIO R DTV I O FOR USE WITH KW 34HD1 DTV RECEIVER ONLY DTV I O FOR USE WITH KW 34HD1 DTV TV ONLY DOLBY DIGITAL OUTPUT OPTICAL VHF UHF DTV DIGITAL TV ANTENNA KW34HD1 REMOTE CONTROL REAR PANEL INPUTS SET BACK BOX HDTV44 ...

Страница 20: ...e voltage minus the Y level is the Blue color level Since this is a picture of a blue screen the voltage is high The bottom waveform is the R Y signal The area corresponding to the horizontal sync pulse in the Y signal is also at 0Vdc The red Y level during a blue screen is below 0Vdc It will be equal to 0Vdc if the Y signal is subtracted PM3394 FLUKE PHILIPS ch3 ch2 ch1 CH1 5 00 V CH2 5 00 V L 12...

Страница 21: ...ENU TV CABLE VHF UHF ANALOG TV INPUT Y PB PR L R S VIDEO VIDEO HD AUDIO OUT VAR FIX L MONO R CONTROL S IN OUT DVD 1 3 FOR USE WITH HD 1080 INPUT ONLY HD L MONO AUDIO R DTV I O FOR USE WITH KW 34HD1 DTV RECEIVER ONLY DTV I O FOR USE WITH KW 34HD1 DTV TV ONLY DOLBY DIGITAL OUTPUT OPTICAL VHF UHF DTV DIGITAL TV ANTENNA KW34HD1 REMOTE CONTROL REAR PANEL INPUTS SET BACK BOX HDTV44 ...

Страница 22: ... s w itc h R F V id e o 1 3 P h o n o ja c k s V id e o S e le c to r S w C o m p o s ite v id e o L R c h a n n e l a u d io D V D P h o n o ja c k s D V D S w itc h Y P b P r L R c h a n n e l a u d io H D P h o n o ja c k s V id e o P ro c e s s o r Y P b P r L R c h a n n e l a u d io The signal path for these inputs is shown below Digital Input VHF UHF antenna HDTV Box accepts all 18 DTV form...

Страница 23: ...26 ...

Страница 24: ... Vertical drive VD signals not only feed the vertical deflection stage but also the picture tilt stage that handles trapezoid correction A controlled level of vertical sawtooth VD signal is used for trapezoid correction This correction signal is mixed with a DC voltage for tilt correction and applied to the N S coil suspended about the bell of the picture tube by the yoke Focus There are two focus...

Страница 25: ...28 ...

Страница 26: ...e video into their luminance Y and chroma C parts The main and sub Y C outputs run parallel paths through similar ICs before leaving the A board The main and sub signals are converted to component video in Chroma Decoders IC2403 sub path and IC2404 main path The Y R y B Y signals are applied to switches IC2405 and IC2406 to enable DVD input selection DVD Input Switches IC2405 and IC2406 can now se...

Страница 27: ...30 ...

Страница 28: ...and 32 Y 2Vp p C 1Vp p Y 1Vp p Cr Cb 0 5Vp p pins 18 20 Changes Y C to component video All signal levels were taken using a color bar input Video Switch Five composite video inputs are applied to video switch IC2006 Serial data from Main Micro IC3251 not shown chooses which input signals take the main and sub picture signal paths The chosen signals go to their respective comb filters The 3D filter...

Страница 29: ...32 ...

Страница 30: ... caption decoder IC2409 is at the output of this YUV switch at IC2406 pin 22 Filtering When high frequency analog signals are sent into a digital stage the high frequency component can create a secondary signal This second signal is called an alias component Alias signals are eliminated by low pass filtering LPF the analog input That is the purpose of the filter networks at the output of IC2406 DT...

Страница 31: ...34 ...

Страница 32: ...s M ID M u lti Im a g e D riv e r A c c e p ts b o th 4 8 0 o r a n d 9 6 0 lin e c o m p o n e n t v id e o im a g e s m a in s u b a n d c o n v e rts th e m in to a tw in p ic tu re The DRC digital circuitry does more than just double the lines though that is the primary objective There are 525 NTSC interlaced lines input 480 viewable lines to the DRC and 960i i interlaced lines leaving It is t...

Страница 33: ...36 ...

Страница 34: ...nes This technique of alternating odd and even fields is called interlacing The NTSC system is often referred to as 525 60 for 525 total scanning lines and 60 fields per second It is also called 480I for 480 net scanning lines interlaced Over the years the 480i system has worked remarkably well But with only 240 lines on screen at any one time the scanning lines can become painfully obvious partic...

Страница 35: ...ason line doublers require elaborate motion detection motion compensation and memory circuits This can get expensive with the better line doublers costing 2 500 or more A new solution DRC Sony s new Digital Reality Creation DRC circuitry is an all new approach to the problem of visible scanning lines Not only does DRC create a clearer picture by doubling the number of active scanning lines it also...

Страница 36: ... television viewing experience Now you can sit up close to the screen immersing yourself in the magic of home entertainment and still not be bothered by visible scanning lines Pictures appear denser and more seamless And in the coming world of Digital TV DTV broadcasting televisions with Digital Realty Creation circuitry will narrow the perceived gap among NTSC ana log sources standard definition ...

Страница 37: ...20 NOTES ...

Страница 38: ...ideo terms that s 480P Digital Television DTV broadcasting embraces both interlace scanning and progressive scanning A convergence technology is needed to link the two previously separate worlds of entertainment and information Sony s solution Sony s new Multi Image Driver MID circuitry contains a special Twin View function that can display either a High Definition or a Standard Defi nition video ...

Страница 39: ...onality Multi Image Driver circuitry also delivers powerful picture in picture ad vantages such as Flexible Twin ViewTM Function Not only can you view two images side by side but you can continuously expand either picture up to two times its normal size New Favorite Channel Automatically shows your eight favorites or the last eight channels you ve watched New Freeze Mode Lets you freeze a broadcas...

Страница 40: ...cond picture comes from the sub picture information in put at IC506 pins 11 23 T w in V ie w P ic tu r e M a in S ig n a l P a th C o m p o n e n t In p u t O u tp u t P u r p o s e B u ffe rs tr a n s is to r s Q 5 7 2 Q 5 7 4 M a in c o m p o n e n t v id e o in p u t C N 5 0 3 p in s 7 9 1 1 IC 5 0 9 p in s 7 7 Y 2 3 V p p 7 6 C b 1 V p p 7 1 C r 1 V p p S u p p lie s s u ffic ie n t c u r r e ...

Страница 41: ...44 ...

Страница 42: ...re tube aging The current drawn by the CRT cathodes is sampled and output pin 5 of each output IC The outputs are multiplexed buffered and AC coupled C3072 to the Video Processor IC3005 pin 41 for analysis The RGB lev els are adjusted to compensate for a weak cathode The AKB circuit starts in IC3005 at turn on by outputting a one line pulse to each cathode from RGB pins 35 37 and 39 These three pu...

Страница 43: ...46 ...

Страница 44: ...circuit also known as the IK circuit is to adjust the level of R G or B drive signal to compensate for picture tube aging The AKB circuit starts in IC3005 at turn on by outputting a one line pulse to each cathode from RGB pins 35 37 and 39 These three pulses occur on different lines and in the blanking area above the picture so they are never seen The three drive pulses are output as long as the v...

Страница 45: ...48 ...

Страница 46: ... location by using vertical and horizontal deflection not station sync signals These signals are shaped into 5Vp p pulses which are input to IC3251 pins 95 and 97 Without either signal there would be no OSD Main Micro IC3251 provides a visual indication of the user command To perform this characters are output as pulses on the respective Or Og and Ob outputs Character Insertion To make the display...

Страница 47: ...50 ...

Страница 48: ... 0 0 1 p in 5 IK o u tp u t 9 0 5 V The red video signal from the video processor is input to the C board and buffered by Q9009 The output is applied to the video output IC This voltage amplifies the input to drive the picture tube IK Output Circuitry The picture tube s cathode current flows through the video output ICs A sample of that current is output from each IC at pin 5 The three IC outputs ...

Страница 49: ...52 ...

Страница 50: ...ivider consisting of resistors and transistors to reduce and control the voltage before it is ap plied to the picture tube s G2 grid G2 Path The current path from CN9002 pin 1 to ground is 1 R9055 R9085 R9067 R9084 2 Q9014 3 Q9012 4 R9081 Both Q9014 and Q9012 transistors are biased on completing the current path to ground The picture tube s G2 voltage is taken at the junction of the resistors and ...

Страница 51: ...54 ...

Страница 52: ...to disorient the tube s residual magnetism as suring proper beam landing and color purity Waveform PSblk Power Sequence Channel 1 AC relay output of Main micro IC3251 Channel 2 Main relay output of Main micro IC3251 Channel 3 DG output of Main micro IC3251 to RY5503 All waveforms are 5Vp p time base 2 sec div This degaussing stage is powered with 60Hz AC immediately after the AC relay is energized...

Страница 53: ...56 ...

Страница 54: ...5Vdc that is output An error voltage changes the converter s oscillator frequency which corrects the 135Vdc Protection Stage The protection stage has many inputs see the Overall Protection Block diagram When a problem is detected this circuit latches the Main Micro s power ON output to ground so the AC relay and TV shuts off Turning off the TV from the remote or front panel resets the latch The pr...

Страница 55: ...58 ...

Страница 56: ... reached T5501 T5502 Common mode rejection transformers to cancel out of phase AC input or TV output noise R5518 Surge limiting resistor The standby transformer T5503 and bridge rectifier D5502 apply approxi mately 23 volts to 12 and 5 volt regulators The standby 5Vdc goes to the infrared remote control receiver and the Main Micro IC3521 The standby 12 volts sent to the H1 board is applied to the ...

Страница 57: ...60 ...

Страница 58: ...OSFETs Q5012 Q5013 12Vp p drive signals from IC5003 pins 1 and 7 150Vp p square wave 63 4kHz Q5012 Source Transformer T5003 286Vp p rough sine wave T5003 pin 8 Multiple secondary voltages Ground isolation Provide various TV voltages IC5008 PH5003 D5024 D5030 5V source from D5041 Reduction of voltages at IC5004 pins 1 and 6 Converter 2 regulation using 5V output as fdbk Kick Start When switched AC ...

Страница 59: ...62 ...

Страница 60: ...fied by IC5003 Q5012 and Q5013 and is applied to a LC circuit consisting mainly of C5040 T5003 The oscillator frequency is positioned above higher than the resonate fre quency of C5040 T5003 Therefore an increase in the oscillating frequency results in a reduced output from the T5003 transformer L Conversely a decrease in oscillator frequency results in a higher secondary voltage Regulation Effect...

Страница 61: ...64 ...

Страница 62: ...imes vertical failure Loss of top or bottom drive signal a No Top drive D5026 shorted Q5012 open IC5003 Vb positive bias voltage pin 6 missing from D5029 b No Bottom drive D5032 bootstrap cap C5039 or D5031 leaky shorted Q5013 open Vertical stage not working because the horizontal FBT voltages are not present caused by insufficient voltage from Converters 1 or 2 IC5003 Normal DC Operating Voltages...

Страница 63: ...66 ...

Страница 64: ...cu s circu it P in c u sh io n co rre ctio n circu it 3 B O V P T V S h utd o w n C o n ve rte r 1 re g u la tio n fa ilu re o scilla to r o ff fre q u e ncy 4 S e ria l D a ta sh utd o w n in stru ctio n fro m D e fle ctio n C o n tro l IC 1 3 0 5 to M a in M icro IC 3 2 5 1 T V S h u td o w n V e rtic a l fa ilu re H o rizo n ta l sca n F B T d e rive d vo lta g e fa ilu re n o H o rizo n ta l L...

Страница 65: ...68 ...

Страница 66: ...the D board means the problem is on the G board It can be caused by A protection latch Q5504 Q5503 defect G board Excessive 15 volts from converter 1 G board The surge relay did not engage G board Measure the 15Vdc CN5002 pin 5 when you power ON the TV again with the remote The trip voltage is 22 volts If the 15V pin is below 22V the problem is the protection latch or the parts around it surge rel...

Страница 67: ...70 ...

Страница 68: ...ages is also monitored by the protection sensing circuits on the D board Q7003 watches the current flowing from the 135V supply through the following sections before arriv ing at the Horizontal Output device Q4018 135V source voltage from converter 1 Q7003 Current sensing Q4022 PWM T7002 FBT Q4018 H Output Leakage or shorts in any component in the above path will permit voltage to pass through D71...

Страница 69: ...72 ...

Страница 70: ...h formed by Q5503 and Q5504 to divert power ON current from IC3251 pin 71 to ground This starves the AC relay driver transistor Q5502 by removing its base bias so the TV shuts down The protection latch remains active as long as the Main Micro IC3251 pin 71 is outputting a power ON command Turning the TV OFF IC3251 pin 71 then goes low resets the Q5503 Q5504 latch The latch can be triggered by any ...

Страница 71: ...74 ...

Страница 72: ...er Q5018 and Q5017 to shut down the TV and blink the light six times A higher voltage at the 5V line means that Converter 2 is not regulating Measure the 5V line with a peak hold DVM to verify the over voltage 135V OCP The 135V OCP circuit is similar to the 5V OCP circuit The 135 volts from Converter 1 is monitored by this circuit for excessive current The 135V from D5015 passes through both R5026...

Страница 73: ...76 ...

Страница 74: ...iv id e r S a m p le s th e P W M d riv e r s u p p ly v o lta g e Q 4 0 0 1 O N K e e p s Q 4 0 0 5 O N Q 4 0 0 5 O N K e e p s o u tp u t a t 0 V d c Initially both Q4001 and Q4005 are turned ON when current flows from 12V through Q4001 e b R4009 R4008 and R4012 to ground When Q4005 is ON its collector voltage is at 0Vdc so the shutdown path ends here A sample of the PWM driver voltage is taken ...

Страница 75: ...78 ...

Страница 76: ... 0 022V If it continues to rise to the trip point of 1 3V the problem is excessive driver PWM voltage from Q4003 or the Q4001 Q4005 sens ing circuit is defective Protection circuit 3 diagram 3 Locate the photo coupler PH4006 pin 3 and monitor its voltage as you turn on the TV and it shuts down The normal voltage here is 0V If it rises to the trip point of 1 5V the problem is a shorted IC4003 cente...

Страница 77: ...80 ...

Страница 78: ...G board Excessive current consumption can be caused by a shorted PWM MOSFET Q4022 shorted T7002 FBT leaky Q4018 or just a high screen control adjustment H Output Supply OVP Circuit Operation The PWM B regulating circuit supplies voltage to the Horizontal Output Transistor Q4018 The following parts monitor this supply voltage H O u tp u t S u p p ly O V P C ir c u it P a r ts N o r m a l C o n d it...

Страница 79: ...82 ...

Страница 80: ...rotection circuit 3 diagram 4 Locate Q7003 collector middle lead or the anode of D7102 and moni tor its voltage as you turn on the TV and it shuts down The normal voltage here will not rise above 0V If it rises to the trip point of 1 5V the problem is excessive current to the PWM regulating circuit FBT or Horizontal Output Transistor Protection circuit 4 diagram 5 Locate IC4004 pin 14 and monitor ...

Страница 81: ...84 ...

Страница 82: ...ost voltage used during vertical retrace tim e When 5V is applied the vertical drive signal is made in IC1305 and output as an out of phase signal pair from pins 21 and 22 Each signal output is 2Vp p The differential out of phase output signals are sent on long signal runs to a different board to take advantage of common mode rejection When the same interference is picked up on both signal lines o...

Страница 83: ...86 ...

Страница 84: ...d phase of the VD signal output IC1305 must be the same as the station s vertical signal Two inputs are used to accomplish this One input is the station sync that comes into IC1305 pin 28 The second input is the sample of the vertical oscillator signal that enters IC1305 pin 11 The two inputs are compared in IC1305 and the frequency and phase of the vertical oscillator is corrected to match Pictur...

Страница 85: ...88 ...

Страница 86: ... a n g e th e s p ik e in to a p u ls e 2 C o n tro l th e p u ls e w id th P W M 3 F ilte r th e o u tp u t in to D C The purpose of this stage is to 1 Make B voltage for the driver MOSFET 2 Regulate this voltage 3 Increase the B voltage when a wide picture is called for Horizontal Output PWM stage H o rizo n ta l O utp u t P W M sta g e S e ctio n s M a jo r p arts P u rp o se P u lse w id th C ...

Страница 87: ...90 ...

Страница 88: ...s sync Buffers IC1705 eliminates any base noise in the horizontal drive signal It per forms this by comparing the input to a fixed voltage set by the R1743 R1745 voltage divider at IC1705 pin 8 Voltages above this threshold are allowed to pass and noise riding along the base line is not output pin 14 The comparator output signal is 12Vp p Q1702 and Q1703 are buffers drivers that provide a fixed cu...

Страница 89: ...92 ...

Страница 90: ...e is re fe re n c e d to th e s o u rc e lik e th e b a s e is to th e e m itte r T u rn O N g a te th re s h o ld v o lta g e is 1 2 V lo w p o w e r o r 2 4 V h ig h p o w e r T O 2 2 0 c a s e o r la rg e r A g a te v o lta g e th a t is b ro u g h t to w a rd th e d ra in v o lta g e tu rn s it O N ju s t lik e a b a s e v o lta g e b e in g b ro u g h t to w a rd th e c o lle c to r p o te n ...

Страница 91: ...94 ...

Страница 92: ... 0 3 P W M s ig n a l D C v o lta g e D a m p e r a n d lo w p a s s filte r IC 4 0 0 6 p in s 1 3 S a m p le d D C fro m v o lta g e d iv id e r R 4 0 0 8 R 4 0 1 1 R 4 0 1 2 to IC 4 0 0 6 p in 3 IC 4 0 0 6 p in 1 D C v o lta g e D C re g u la tio n Q 4 0 0 7 IC 4 0 0 6 p in s 5 7 C N 4 0 0 7 p in 1 0 5 V w id e 0 V N o rm a l p ic tu re w id th IC 4 0 0 6 p in 7 D C v o lta g e P u ls e w id th ...

Страница 93: ...96 ...

Страница 94: ...iv C h a n n e l 1 H D riv e C N 4 0 0 9 p in 1 0 1 2 V p p C h a n n e l 2 D e la y e d d riv e C N 4 0 0 9 p in 9 1 2 V p p C h a n n e l 3 P W M O u tp u t Q 4 0 2 2 d ra in 1 4 4 V p p C h a n n e l 4 R e f F B T p u ls e F B T N A T im e b a s e 5 u s e c d iv Horizontal Drive Pulse First Delay Monostable multivibrator MMV IC1704 pins 2 13 and comparators IC1705 pins 1 7 perform the first del...

Страница 95: ...98 ...

Страница 96: ... pin 13 Makes a low pulse to end the window pulse Comparator IC1705 pin IC1705 pin Inverter The scope shot shows the H drive signal input IC1704 pin 2 and output of the first MMV ch 1 2 which triggers the second MMV closing the window The second MMV output is shown in the last waveform ch 4 It is reset at the end of its timing by the inhibit pulse applied to IC1704 pin 11 ch 3 After being reset th...

Страница 97: ...100 ...

Страница 98: ...e ramp ch 2 and the input pulse used to reset it ch 1 The ramp waveform ch 2 can be compared to the output pulse ch 3 to see that approximately 1 3 volts was input at IC4004 pin 7 to produce this pulse width The output waveform ch 4 shows the pulse is inverted and amplified by the output MOSFET W a v e fo rm H D 2 P u ls e W id th C o n tro l N a m e L o c a tio n V o lta g e d iv C h a n n e l 1 ...

Страница 99: ...102 ...

Страница 100: ...D D C is W id th is W id th is lo w e r N a rro w e r N a rro w e r A positive gate pulse is used to turn OFF the P channel PWM output de vice Q4022 so the narrower the pulse the higher the B voltage PWM Output Circuit This output circuit consists of a buffer Q4015 and Q4014 which is used to supply drive current to the gate of Q4022 An inverted pulse is output at Q4022 s drain and applied through ...

Страница 101: ...104 ...

Страница 102: ...leaves IC1305 pin 20 as a parabola waveform labeled EW east west correction The low frequency 60Hz signal is added line by line using a horizontal AFC pulse input IC1803 pin 8 The output signal at IC1803 pin 14 looks like the E W parabola chopped up at a horizontal rate W a v e fo rm P in 1 P a ra b o la S ig n a l P ro c e s s in g N a m e L o c a tio n V o lta g e d iv C h a n n e l 1 E W p a ra...

Страница 103: ...106 ...

Страница 104: ...mV CH3 5 00 V BWL CH4 100 V CHP MTB10 0us ch1 1 2 3 4 T A sample of the horizontal flyback pulse from Q4018 s collector is buff ered by Q1804 This signal performs two functions 1 Pincushion modulation at IC1803 pin 11 2 Horizontal AFC at IC1305 pin 25 automatic picture phase lock cor rection ...

Страница 105: ...108 ...

Страница 106: ...C differential output pins 2 and 8 N S Coil Changes current flow into a m agnetic field CN1901 pins 1 and 3 M agnetic field User Tilt Adjustment The user has an on screen display OSD menu number that displays the tilt amount from 10 to 10 The number zero should correspond to no DC voltage entering the N S coils if the coarse tilt adjustment in the ser vice mode is set correctly This chart shows DC...

Страница 107: ...110 ...

Страница 108: ...ount of sawtooth signal output is set by a single DC voltage input IC1902 pin 10 M u ltip lie r IC 1 9 0 2 O u tp u ts O u tp u t IC 1 9 0 2 p in 9 D M C a te g o ry H T P Z re g is te r 5 D a ta In p u t IC 1 9 0 2 p in 1 0 V o lta g e W a v e fo rm 3 2 N o rm a l 4 4 4 V 0 2 V p p 4 6 V 0 M in im u m 2 1 8 V 3 V p p 4 5 1 V 6 3 M a x im u m 6 5 8 V 2 5 V p p 4 6 8 V 3 4 n o o u tp u t 4 5 8 V 0 ...

Страница 109: ...112 ...

Страница 110: ...static focus voltage from FBT T7002 to create the final focus voltage fv that is applied to the picture tube s focus electrode This voltage corrects the screen s left and right side fo cus Circuit Block Operation The four blocks along the top and the three blocks along the bottom of the dynamic focus block diagram make up the dynamic focus stage that feeds the dynamic focus transformer T7001 The t...

Страница 111: ...114 ...

Страница 112: ...reference voltage are input to the first block A pulse is cre ated that begins when the electron beam is at the right side of the screen After the beam has retraced and ventured into the left side of the screen the pulse ends This pulse marks the area that dynamic focusing takes place at the left and right sides of the screen The second block inverts this location pulse and buffers it for voltage ...

Страница 113: ...116 ...

Страница 114: ...ls e O u tp u t IC 1 5 0 2 p in 1 4 1 2 V p p T im e b a s e 5 u s e c d iv Pulse Manufacture The horizontal rate ramp signal is input at IC1502 pin 9 and a DC voltage is input at pin 8 of this comparator This DC voltage input at pin 8 governs the output pulse width at IC1502 pin 14 When a normal 4 3 ratio picture is requested by Main Micro IC3251 not shown D A Converter IC1702 pin 1 is LOW 1 7Vdc...

Страница 115: ...118 ...

Страница 116: ...urce to the drain The input volt age of only 12Vp p at Q7009 s gate is amplified to 135Vp p at its drain The signal is also inverted This signal is low pass filtered into a DC volt age by L7003 and C7032 The resultant DC voltage is applied to T7001 pin 11 D7010 at Q7009 s Drain lead prevents a negative voltage there The negative voltage is caused by the collapsing field of the resonate tank circui...

Страница 117: ...120 ...

Страница 118: ...pin 4 ch 2 A DC reference voltage is input to pin 5 of this comparator The reference voltage is chosen to produce a low going pulse ch 4 from the comparator prior to the next FBT retrace pulse ch 1 W a v e form D F f P u lse M fg N a m e L o ca tio n V o lta g e d iv C h a n n e l 1 F B T p u lse F B T N A C h a n n e l 2 H R e se t p u ls e Q 1 6 1 4 b a se 5 V p p C h a n n e l 3 R a m p vo lta ...

Страница 119: ...122 ...

Страница 120: ...r focus correction This means the final dynamic focus correction signal Q7012 drain starts before the FBT retrace signal and ends after it This corresponds to the left and right side of the TV picture where dynamic focus correction is needed This signal is coupled by DFT T7001 pin 4 to the static focus voltage FBT T7002 pin 16 for dynamic focus correction W a v e fo r m D F g S ig n a l A m p lifi...

Страница 121: ...124 ...

Страница 122: ...his quadrapole focus circuit reshapes the spot by using the magnetic field from four coils mounted at the picture tube neck The four QP coils work in magnetic pairs either pushing or pulling the beam so it is oblong in transition but round at the target screen The diagram shows the effects of two facing QP coils Dynamic Quadrapole Circuitry To reshape the spot in the four corners of the picture tu...

Страница 123: ...126 ...

Страница 124: ...ic Quadrapole correction signals were provide by parabola 1 and 2 The higher current used to manufacture the large magnetic fields in the QP coils and introduce the lower 60 Hz frequency parabola signals into the horizontal frequency scan are created by IC1603 and Q1605 The source of this drive signal is comparator IC1603 It manufactures a pulse to mark the areas of the screen that need to be corr...

Страница 125: ...128 ...

Страница 126: ...er s reception area and the customer has a good antenna that is pointed properly Error LED illuminates with a flash of red light whenever a non correctable error is detected in the DTV data When the TV is tuned to a valid DTV channel the Power on LED should be on steadily the heartbeat LED should be flashing the DTV Signal LED should be lit I O Connector DTV Signal LED green when lit Error LED red...

Страница 127: ...B is on This heartbeat indi cates that the operating program used to run the CPU in the SBB is run ning properly i e the program is not locked up The two LED s on the front end board may be clear in color when they are not lit but when lit one will be red and the other will be green When the SBB is receiving a valid DTV signal on the physical channel it is tuned to the green LED will be lit The re...

Страница 128: ...iii ...

Страница 129: ...he procedure is on pages ___ of the adjustment manual B The B board is plugged into the G board and secured with a plastic L bracket Remove the plastic L bracket from the G board by squeezing the tabs under the G board Note that white connectors CN3002 CN3007 are not used Main Micro Processing Sound Effect Processing for Dolby inputs Video Processing Video some deflection memory 1 No OSD menu or c...

Страница 130: ...determine if this board is at fault 2 Standby light blinks 2 times pauses and repeats OCP 3 Standby light blinks 4 times pauses and repeats No Vert Touch up adjustments of picture size and position picture distortion adjustments are on page __ of the adj manual G Remove rear panel ground shield Unscrew board and lift out with 3 boards plugged into it Unclamp the outer 2 A B boards that plug into t...

Страница 131: ...s s e r v ic e m o d e e n tr y T V V id e o 1 3 D V D H D n o s y n c Id e n tifie s t h e in p u t u s e d fo r t h e d is p la y N V M G G N V M N G G N V M G N G D is p la y s th e c o n d it io n o f t h e N o n V o la tile M e m o r y I C s T h e fir s t G IC 3 2 5 2 o n t h e B b o a r d T h e s e c o n d G IC 1 3 0 4 o n th e M b o a r d V e r s i o n 4 1 M a in M ic r o v e r s io n D e s...

Страница 132: ...e g is te r R e g is te r G ro u p N a m e N u m b e r o f m e m o ry lo c a tio n s re g is te r M e m o ry L o c a tio n N a m e s G e o m e try m o d e s S D A 9 3 6 1 7 N o rm a l F u ll C a p tio n Z o o m W id e Z o o m S D D T V H D D T V D M 7 N o rm a l F u ll C a p tio n Z o o m W id e Z o o m S D D T V H D D T V C X A 8 0 7 0 7 N o rm a l F u ll C a p tio n Z o o m W id e Z o o m S D D ...

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