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®

Training Manual

Projection Television

Circuit Description and Troubleshooting Course: TVP-08R1

Circuit Description and Troubleshooting:
Prepared by: National Training Department Sony Service Company A Division of Sony Electronics Inc.

Course presented by______________________________________ Date___________________________________________________ Student Name ___________________________________________

Sony Service Company A Division of Sony Electronics Inc ©1998 All Rights Reserved Printed in U.S.A.

Sony and Trinitron are registered trademarks of Sony.

S
SEL Service Company A Division of Sony Electronics Inc. 1 Sony Drive Park Ridge, New Jersey 07656

TVP080299

Printed in U.S.A.

Table of Contents
Features
Overview Picture Audio

1
1 1 1

DC Protect AC Protect

13 13

Soft Start
Overview Soft Start - Power ON

15
15 15

Self-Diagnostics Board Descriptions Power Supply Block
AC Input Power ON Converter Regulation Protection

3 5 7
7 7 7 7 7

Converter
Overview Operation

17
17 17

T6002 Secondary (Audio B+)
Overview Operation

19
19 19

T6001 Secondary-1
Overview +/- 15 Volts + 11 Volts +/- 22 Volts Distribution

21
21 21 21 21 21

AC Input and Switching B+
Overview AC Input B+ Rectifier

9
9 9 9

Standby Power Supply
Overview Standby Switching supply

11
11 11

T6001 Secondary-2
+7 Volts +135 Volts -135 Volts +33 Volts

23
23 23 23 23

Vcc Switch (Power On)
Overview Power ON

13
13 13

Distribution

23

M (Main) Bus P (Auto Registration) Bus MID Bus

37 37 37

Regulation
Overview Operation

25
25 25

Video Path Block
Inputs Main Video Sub-Video IC511 Video Processor

39
39 39 39 39

DC Protection
Overview Shut Down +135 Volt Over Voltage +135 Volt Over Current Protection +19, +22, +7 Volt LVP

27
27 27 27 27 27

Input Switching
Overview Inputs Outputs

41
41 41 41

PS Troubleshooting
Overview Troubleshooting

29
29 29

Main Y and C Buffers
Overview Y Buffer Sync Separator C Buffer

43
43 43 43 43

Protection Block
Overview Diagnostic Indication Circuit Description

31
31 31 33

Reset
Overview Initial Reset Power ON Reset

35
35 35 35

3D Comb Filter
Overview What is a 3D Comb Filter? Circuit Description

45
45 45 45

System Block Diagram
Overview B (Standby) Bus

37
37 37

Main Chroma Decoder
Overview C Processing

49
49 49

Y Processing H and V Sync 3.58 MHz

49 49 49

Sync Processing

65

IK/AKB
Overview Video Drive IK Troubleshooting

69
69 69 69 69

Main YUV Switch
Overview Inputs Output Selection

51
51 51 51

Sync Paths
Overview Sync Paths

71
71 71

DRC - Digital Reality Creation DRC Block
Overview Inputs DRC Processing Outputs Troubleshooting

53 57
57 57 57 57 57

Deflection Block
Overview Vertical Horizontal High Voltage Convergence

73
73 73 73 73 73

MID - Multi Image Driver MID Block
Overview MID Inputs MID Processing MID Outputs MID Troubleshooting

59 63
63 63 63 63 63

Horizontal Deflection Block Horizontal Jungle
Overview H Drive

75 77
77 77

H Out
Overview H Drive H Out Horizontal Centering

79
79 79 79 79

Video Processor
Overview Video Processing

65
65 65

Pin Amp
Overview Pin Amp

81
81 81

Overview HV Drive Peak Drive

95 95 95

H Protect/HP
Overview HP H Protect

83
83 83 83

HV Regulation Control
Overview Regulation Control +12 High Voltage LVP

99
99 99 99

Vertical Deflection Block H BLK Delay and 1/2 H + Odd/Even
Overview H BLK Delay 1/2 H and Odd/Even

85 87
87 87 87

HV Regulation PWM
Overview Sawtooth Generator PWM

101
101 101 101

HV Stop 2
Overview ABL Hold Down

103
103 103 103

VDSP
Overview VCO CDP DSP DAC

89
89 89 89 89 89

HV Stop 1
Overview ABL High Voltage Block Tap +125 Volt OVP

105
105 105 105 105

V Out
Overview V Out V Protect

91
91 91 91

Convergence Block
Overview Convergence Auto Focus (Auto Registration)

107
107 107 107

High Voltage Block HV Drive

93 95

Sensor Amp
Overview Auto Focus Circuit Description

109
109 109 113

BD Input
Overview Digital Convergence

115
115 115

BD Output
Overview IC1707 Regi Correction

117
117 117

Convergence Out
Overview Regi Mute Convergence Amp

119
119 119 119

Service Mode
Overview Normal Service Mode PJED Mode

121
121 121 121

Protection Block
Overview Diagnostic Indication Circuit Description

127
127 127 129

1

Features
Overview
The models covered by this manual are the new KP53XBR200 and the KP61XBR200. These two models are electrically identical. The differences have to do with screen size. Therefore they use different cabinets, screens, mirrors and tubes. These sets also have a Self Diagnostic system.

·

First Surface Mirror ­ Unlike most mirrors, the reflective surface is on the front of the mirror glass. This improves brightness and contrast, and eliminates ghosting caused by the reflected light passing through the glass. Advanced Velocity Modulation Advanced High Voltage Regulation ­ Eliminates distortion and focus fluctuations that occur when changes in brightness levels cause changes in the high voltage. Noise Reduction Shading Compensation ­ Eliminates color shift and hot spots that can occur due to the angle of the picture tubes to the mirror. Wideband Video Amplifier Multi Image Driver ­ Digital-editing technology that provides versatility in controlling on-screen images. Used in Picture and Picture and Channel Index modes. Twin View Picture-in-Picture ­ Allows for viewing two pictures simultaneously and the ability to expand either image up to double its normal size. Free Layout Picture-in-Picture ­ Allows the PIP window to be placed anywhere on the screen. XDS (Extended Data Service) ­ Receives data information services that some stations may broadcast. This data includes time, station call letters, etc.

· ·

· · · ·

Picture
The two models share the following picture features: · · · · Advanced Pro-Optic System ­ Sony technology that allows full corner to corner focusing. New Extended Definition CRT ­ Allows corner to corner focusing to be increased by 25% over last year's model. MICROFOCUS Lens System Digital Reality Creation (DRC) ­ DRC uses line doubling and pattern recognition algorithms to take the NTSC signal to a near HDTV equivalent. This will be discussed in more detail later. Double Scan Technology Auto Focus Full Digital Convergence ­ Allows the setting of V and H center and skew by the customer. This convergence system can produce a sharper picture and is less susceptible to drift due to aging or shipment. High Performance Video Processor 3D Digital Comb Filter Brightview Dual Component Screen ­ The screen contains a Thin Film Fresnel that brightens and sharpens the picture, and a Fine Pitch Lenticular screen that achieves higher resolution by using black stripes to increase contrast. Built-in High Contrast Screen

·

· ·

· ·

Audio
The two models share the following audio features: · · · · · · MTS Stereo with dbx NR Dolby Pro Logic Surround Sound Front Left/Right Audio Power - 20Wx2 Center Audio Power ­ 20W Surround Audio Power ­ 15Wx2 Center speaker input for use with a separate Dolby Pro Logic A/ V Reciever

· · ·

·

NOTES

2

3

Self-Diagnostics
Overview
The RA-4 chassis employs a Self-Diagnostic system that uses the Timer LED and an on screen menu to help indicate where the problem with the set has occurred. You will generally have to use the flashing LEDs since the set will be shut down. AC power must be disconnected in order to turn the set off once shutdown has occurred. When a failure occurs, all of the circuits covered by the Self-Diagnostics, except AKB, send a signal to the OSD CPU. The OSD CPU sends data to the Main CPU that indicates how many times the Timer LED will flash. The AKB circuit located in the Video Processor IC sends data over the I2C bus directly to the Main CPU. In addition, each circuit, except AKB and High Voltage, send a signal to the latch circuit to shut the set down when failure occurs.
< FRONT PANEL >

The number of times the LED blinks may correspond to that shown in the following table:
Diagnosis Item ·Power not ON +B OCP detection +B OVP detection V detection AKB detection H detection HV abnormality detection Audio abnormality detection WDT (Syscon) Standby/ sleep lamp, Number of Blinks Not lit LED blinks 2 times LED blinks 3 times LED blinks 4 times LED blinks 5 times LED blinks 6 times LED blinks 7 times LED blinks 8 times LED blinks 9 times Self-diagnosis screen display, Diagnosis Item Results 2 : +B OCP 3 : +B OVP 4 : V STOP 5 : AKB 6 : H STOP 7 : HV 8 : AUDIO 9 : WDT XX XX XX XX XX XX XX XX

* : XX the range of values for number of operations is 00-99.
and the number remains at 99.

For 99 or higher there is no count up

If the problem is intermittent and you can get the set to operate, you can display a menu showing the number of times failures have occurred. This is done by pressing the following sequence of buttons on the remote. Display Channel 5 Vol - Power The display will look as follows.

·EXAMPLE · +B overcurrent · +B overvoltage

SELF CHECK 2 : +B OCP 3 : +B OVP 4 : V STOP 5 : AKB 6 : H STOP 7 : HV 8 : AUDIO 9 : WDT XX XX XX XX XX XX XX XX

TIMER/STANDBY indicator

· Vertical deflection stop

2 : +B OCP

XX

2 times 3 times 4 times
Lamp ON : 0.3 seconds Lamp OFF : 0.3 seconds Lamp OFF : 3.0 seconds

XX the range of values for number of operations is 00-99. For 99 or higher there is no count up Diagnosis and the numberremainsat 99. Results

4

5

Board Descriptions
Overview
The models covered by this manual are the new KP53XBR200 and the KP61XBR200. These two models are electrically identical. The differences have to do with screen size. The table below shows which circuits are present on each of the boards. This will help if you are doing board level (SAYS) or component level repair.

Name A BD BM BR CR,CB,CG D G HA HB HC K U ZR,ZG,ZB Tuners, A/V switching, RGB processing, H Jungle, VDSP, Syscon Auto registration (Digital Convergence) MID (Multi Image Driver) DRC (Digital Reality Creation) CRT drive and IK feedback. H and V deflection, Sub-deflection, HV, HV Regulation Power supply Front panel controls, Power and Timer LEDs Front video inputs, Auto Focus and Setup buttons Remote sensor Audio Processing and Audio Outputs S Link Input/Output Hor. and Vert. deflection and sub-deflection coils, VM

Circuits contained

HC HA

ZG ZR CR

HB CG ZB CB K U A BM BR D BD

G

6

7

Power Supply Block
AC Input
When the unit is first plugged in, AC power passes through two line filters and is applied to the Standby Power Supply. This is a switching power supply that produces the Vcc source voltage and the standby +5V (RM+5V) for System Control. When the set is turned ON, the AC input is applied through RY6001 Power Relay to the switching B+ rectifier, which supplies power to the Converter circuit. The switching B+ rectifier is monitored at each of its outputs. The negative side of the switching B+ rectifier is monitored to ensure that RY6002 is activated. RY6002 is closed to bypass the In-Rush Current Limiter Resistor when the set is turned ON. When RY6002 is closed, it shunts In-Rush Current Limiter Resistor so that the negative side of the bridge is connected to ground. If the relay is not closed, a voltage will be developed to shut down the set. The positive side of the switching B+ rectifier is monitored to hold the secondary voltages down if the AC voltage should be too low. This is performed by monitoring the switching B+ voltage and applying that voltage to the soft start circuit. This is done because of the excessive current draw when the switching B+ is low.

Converter
When the Oscillator circuit begins oscillating, it outputs two signals that are 180 degrees out of phase. These signals are applied to the converter circuit. The converter circuit contains two Driver ICs that drive two push pull transistor circuits. These circuits drive two transformers that create the AC voltages, which are rectified by the two secondary supply circuits to power the rest of the set.

Regulation
Once the secondary supplies begin to generate DC voltages we can begin to regulate their output. This is done using the +11 volt and +135 volt lines. The +11 volt line is used to power the regulation circuit while the +135 volt line is monitored to regulate the supplies. The +135 volt line is sent to the regulation circuit to produce an error voltage that is fed back to the oscillator circuit. This voltage controls the frequency of the oscillator. Changes in the frequency cause changes in efficiency of the transformers, which in turn cause the voltage to become lower or higher.

Protection
In addition to the three protection circuits on the AC side of the supply, there are additional circuits on the DC side. The +135V line is checked for OVP and OCP. If one of these conditions occurs, a voltage is sent to the protect latch to turn it ON. The latch shuts down the set by turning OFF the Vcc switch. A voltage is also sent to the System Control circuit for the self-diagnostic system. In addition, the 11V line is compared to the +19, +22 and +7 volt lines. If these voltages fall below a specified level, the protect latch will be activated and the set will shut down. There is no indication in the self-diagnostic menu that this circuit has been activated.

Power ON
When Power ON is selected using the remote or the front panel switch, a signal is sent from IC1008 Main-CPU to the Vcc switch section on the G board. The Vcc circuit sends voltage from the Standby supply to the Oscillator and Soft Start circuits. When this voltage reaches IC6003 Oscillator, it begins oscillating. The Soft Start circuit is activated at the same time. This circuit keeps the oscillator at a certain frequency (175KHz) for a specified period of time. This keeps the initial start up voltage low and prevents excessive back EMF from destroying the converter transistors. When regulation begins, the normal operating frequency is around 73KHz.

8

9

AC Input and Switching B+
Overview
The AC Input and Switching B+ circuit is used to filter the AC line voltage and generate the DC voltage necessaary to run the switching supply.

B+ Rectifier
When power is turned ON, the AC line voltage is applied across D602 Bridge Rectifier because RY6001 Power Relay is closed. D6002+ outputs 130 volts which is filtered by C6008, C6010 and L6003. This voltage is used as the B+ for the switching power supply converter circuit and is fused by F6002. D6002- is connected to ground through R6010 In-Rush Current Limiter at initial power ON. When the secondary supplies begin to run, RY6002 will be closed which connects D602/4 - to Hot ground.

AC Input
AC enters the G board at CN6004 when the unit is plugged in. It then passes through F6001 and L6001 and L6002 Line Filters. L6002/3 is the High side of the AC line and splits off to two places. It is used to power the Standby +5V supply and is connected to one of the contacts of RY6001 Power Relay. There are a few protection components in place in addition to F6001 Fuse. There are two spark gaps across the AC line at CN6004 AC Input. There is also one across the AC line after F6001 Fuse. Two capacitors, C6001 and C6002, are present on either side of L6001 Line Filter. VD6001 is a VDR across the L6002/1 and 3 for spike protection.

Switching B+ Low Voltage Protect
Both outputs of the D6002 Bridge Rectifier are monitored to cause shutdown of the set. D6002+ has a sample voltage sent to the Soft Start circuit to monitor for under voltage. If the voltage at this point is too low, the Soft Start circuit will raise the frequency of the switching supply, thereby lowering the secondary output voltages and disabling regulation. The lowering of the secondary voltages will also cause RY6002 to open or may shut the set down. Due to the fact that the power supply voltages will be lowered, the set will indicate an AKB shutdown by flashing the Timer LED five times, pausing, and then repeating. This action will be discussed in greater detail in the Soft Start section.

Troubleshooting
Problems in this area are usually the result of line spikes or lightning. If you have a dead set and suspect lightning damage, you should remove the G board by removing one screw and pulling it out. A quick visual check can be performed by looking on both sides of the board for burnt traces or components. If F6001 is open, be sure to check for any burnt components. If everything looks OK, then check the voltage across VD6001. If the line voltage is not present there, continue to work your way back checking across the AC line until you find an open component.

In-Rush Current Limiter Protect
D602/4 is monitored to ensure that the R6010 In-Rush Current Limiter has been switched out of the circuit by RY6002. If it has not, a voltage will be developed across it that is rectified and sent to the base of Q6004 AC Protect. If Q6004 AC Protect is turned on, IC6003 Oscillator will be shut down. This will cause no output from the switching supply. Keep in mind that there will be 150 volts present at F6002 since the power relay is still turned ON. In addition, the Timer LED will flash twice, pause and repeat. You will not be able to shut the set OFF using the remote or the front panel switch. The set will have to be unplugged to attempt to restart the set.

10

11

Standby Power Supply
Overview
The Standby Power Supply is used to develop the voltages that are required by the set in order for it to turn ON. One of these voltages is used to supply power to the System Control ICs. This voltage is a regulated 5 volts and is called RM+5. The other voltage is used as the source voltage for Vcc, which is the low voltage supply for the switching power supply. The AC input to the standby supply is monitored for overvoltage. It will shut the Vcc switch OFF if there is a problem.

RM+5
As IC6001 PWMSW voltages are induced in the secondary windings of T6003 SRT, one of these voltages is used to develop the RM+5 line. The signal from T6003/7 is rectified by D6120 and filtered by C6137, C6138 and L6113. This voltage is input to IC6104/1. IC6104 5-Volt Regulator outputs 5 volts from pin 2. This is the RM+5 line on the G board. It is called ST-5V on the A board.

Regulation
The secondary winding at pins 3 and 4 of T6003 SRT develops a voltage that is rectified by D6015. This voltage is used for two purposes. It is the source voltage for the Vcc switch and the feedback voltage for regulation. This voltage passes through D6012, D6011 and R6021, and is input to IC6001/4. Pin 4 is the regulation input for IC6001 PWMSW.

Standby Switching Supply
The line AC from L6002/3 is rectified by D6001 and D6003 and filtered by C6009. This voltage is monitored for overvoltage via D6035 and is used to power the standby supply. This voltage then passes through fusible resistor R6012, then to T603 SRT. IC6001 is connected to T6003/ 1 and begins switching when the voltage arrives. IC6001 PWMSW is a self-starting N-channel MOSFET switching device with a self contained oscillator and error loop amplifier used for regulation.

12

13

Vcc Switch (Power On)
Overview
When Power On is selected, IC1008 Main CPU sends a signal to the G board to turn ON the Vcc switch. The Vcc voltage powers the Soft Start, Oscillator and Driver circuits. There is a connection from the latch circuit to shut OFF the set if there is a problem on the DC side of the power supply. In addition, there is a connection from the Standby Source Voltage that will shut down the supply if the AC line voltage becomes to high.

DC Protect
The DC protection latch circuit is connected through D6111 to the power ON line at the junction of R6112 and R6121. When the protection latch is activated, it pulls the O Relay line LOW and turns power OFF by turning and holding Q6014 OFF.

AC Protect
The Standby Source voltage is monitored in case there is an overvoltage problem on that line. If the voltage from the Standby Source voltage goes too high, it will cause the voltage at the cathode of D6035 to rise above 12.6 volts. The voltage at Q6013/B will be enough to turn it ON. When this occurs, Q6013 conducts, causing Q6012 to conduct. This action causes the Q6001 to turn OFF, thereby shutting down the set.

Power ON
When Power ON is selected using either the remote or the front panel switch, 5 volts is output from IC1008/56 O Relay. This voltage travels from CN505/3 on the A board to CN6101/3 on the G board. It then goes through R6112, R6121 and D6112, placing .6V at Q6104/B. This turns Q6104 ON and causes Q6104/C to pull IC6104/2 to ground. This turns the phototransistor inside IC6104 Vcc Switch ON. When this occurs, current flows through the B-E junction of Q6001. When Q6001 turns ON, it causes Q6011 VccSW to turn ON. This switches the Standby voltage through Q6011 VccSW where it is called Vcc. Vcc turns RY6001 Power Relay ON, as well as powering the Soft Start, Oscillator and Driver circuits.

14

15

Soft Start
Overview
A Soft Start circuit is necessary to keep the oscillator that drives the switching circuit above the normal operating frequency of the tuned circuit that is in the switching supply circuit. If this frequency is not above the normal operating frequency at start up, the voltage at the secondary could become too high and cause damage to the set. The soft start circuit causes the oscillator to start at a frequency high above the normal operating frequency by holding the regulating voltage down at initial turn ON of the set. This circuit is also activated if the Switching B+ voltage falls below a certain level.

Soft Start - LVP
The soft start circuit can also be activated if the voltage from D6002/3 Switching B+ goes too low. When the voltage across R6007 drops below 12.6 volts, it will cause Q6002 to turn OFF. This causes Q6003 to turn ON. When Q6003 is ON, the cathode of D6014 will be held at ground potential. This is the same condition that occurs at turn ON, therefore the oscillator will oscillate at a high frequency and this will reduce the output voltages from the secondary supplies. If this occurs while the set is operating, it will shutdown. The set will act as if there was an AKB failure, the Timer LED will flash five times, pause and then repeat.

Soft Start ­ Power ON
When Power ON is selected, the Vcc switch supplies voltage to IC6003/ 12 Oscillator. This oscillator is connected to the regulation line that begins to develop voltage. This voltage is held LOW at Q6006/E while C6016 is charging. Once C6016 is charged, the regulation line is controlled by IC6005/4. Q6005 provides a discharge path for C6016 when the set is turned OFF. This is important because if C6016 is not completely discharged, the oscillator may output the normal operating frequency during Power ON. The discharge path would be through Q6005/C-E junction. Q6005 is OFF during the set's operation because of the voltage applied to it from IC6011/ 3. Be careful when measuring voltages at Q6005/B as this circuit is easily loaded by a meter or a scope. It is best measured using a scope and a 10X probe.

16

17

Converter
Overview
Simply put, the converter circuit switches the DC Switching Supply B+ ON and OFF to create an AC signal. The converter in this set consists of two Driver ICs that drive two sets of N-channel MOSFET transistors. The drivers use the output signal from the oscillator to switch the transistors. These transistors are switched 180 degrees out of phase and are parallel with the two Power Input Transformers.

Operation
Two signals 180 degrees out of phase are applied to the Hi and Lo side inputs. The Hi side input of IC6002/10 is the same phase as the Lo side input at IC6004/12. The Low side input at IC6002/12 is the same phase as the Hi side input at IC6004/10. These signals are amplified and output in phase with their inputs. The Hi side of each of these drivers has a floating power supply that boosts the output level of the signal. The input to this supply is at IC6002/ 6 and IC6004/6. The return is at pin 5 of IC6002 and IC6004. This floating supply allows a 130 Vpp signal to be output for each Hi side driver.

If IC6002/7 is outputting a High signal, then Q6008 turns ON. When Q6008 is ON, it allows the 130-volt Switching B+ to be present at Q6008/ S. This voltage is applied to IC6002/6, the floating supply input, and also to C6022 and C6023. The signal seeks ground through Q6009, which is always ON when Q6008 is ON. Current flows through the transformers T6002 and T6001 while C6022 and C6023 are charging. At the same time, the signal outside of IC6002/1 Lo side output is Low. When the signal at Q6008/G goes Low, the signal at Q6007/G goes High. This causes C6022 and C6023 to be connected to ground. At the same time, Q6010 is turned ON and Q6009 is turned OFF. This causes current to flow through the transformers T6001 and T6002 and capacitors C6022 and C6023. This cycle continues while the set is running and causes sine waves to be seen at T6001/1 and T6002/4. This signal is induced into the secondary of the transformers to produce the power supply output.

18

19

T6002 Secondary (Audio B+)
Overview
The secondary winding of T6002 PIT is used to develop two voltages - +/ -19 volts. These voltages are used to power the K board, which contains all of the audio circuits.

Troubleshooting
If the rest of the power supply is working, but there is a problem with these supplies, you should suspect a problem on the K board. The set can be run with CN6102 unplugged. If the correct voltages are measured at CN6102, then the problem is on the K board. If PS6104 and PS6103 are open, it would be a good idea to power the unit without CN6102 disconnected. If everything appears to be OK, check the K board for shorts on the +/- 19 volt lines. If none are found, then plug CN6102 in and power up the unit.

Operation
The voltage induced into the secondary winding of T6002 is used to develop +/- 19 volts. This voltage is used to supply the Audio section (K board) and is fused with PS6103 and PS6104. This voltage is rectified by D6116 and filtered by C6121 and C6129 to create the +19 volt supply. It is also rectified by D6114 and filtered by C6120 and C6128 to create the ­19 volts. The +19 volt supply is output at CN6102/7 and 8. It also goes to D6122/K, which is part of the protection circuitry. The ­19 volt supply is output at CN6102/2 and 3.

20

21

T6001 Secondary-1
Overview
There are four secondary windings on T6001 PIT. The voltages induced in these windings are used to power everything in the set, except for the audio section. The voltages developed here are +/- 15 volts, +/- 22 volts, +11 volts, +7 volts, +/- 135 volts and +33 volts.

+/- 22 Volts
The voltage from the winding of T601/14 and 15 is applied across D6108 through PS6105 and PS6106. C6125, C6135 and L6112 filter the rectified voltage. The voltage is used on the G board by the protection circuit and it exits the G board at CN6105/1. The winding of T6001/14 and 15 is applied across D6117 through PS6105 and PS6106. C6124, C6134 and L6111 filter the rectified voltage which leaves the G board at CN6105/6. The +/- 22volt lines are used to power only the Convergence amplifiers on the D board.

+/- 15 Volts
The voltage from the winding of T6001/11 and 12 is applied across D6105 Bridge Rectifier. C6119, C6132 and L6108 filter the positive output of D6105/3. This output is used for three things. First, it is applied to Q6106/ E, which turns Q6106 ON and allows current to flow through its E-C junction. It passes through R6141 to RY6002 In Rush Current Limiter Relay. It turns the relay ON when the voltage is sufficient. If the voltage does not rise to a sufficient level or there is a problem with Q6106, the set will shut down. Next it is sent to D6126/A, which is part of the protection circuitry. Lastly it is sent to CN6105/3, CN6106/5 and CN6104/2 where it is sent to the D and A boards. The negative output from D6105/3 goes through R6122, R6123 and R6124, which are parallel. C6118, C6131 and L6109 then filter this voltage. It is then output from CN6105/4 and CN6106/6, both of which go to the D board. These lines are used to produce other voltages on the D board. These voltages are +/- 12 volts and +/- 5 volts.

Distribution
The table below shows the circuits powered by the voltages previously discussed:

S u p p ly +15 -1 5 + 1 2 (D )

C ir c u its V e r t ic a l O u t I C 5 0 0 4 , 1 2 V o lt r e g u la t o r I C 5 0 0 2 ( D b o a r d ) , I C 5 0 2 1 2 V o lt r e g u l a t o r ( A b o a r d ) V e r t ic a l O u t I C 5 0 0 4 , - 1 2 V o l t r e g u la t o r I C 5 0 0 1 V , H , B + , H V , a n d I K p r o t e c t io n c i r c u it s , S h a d in g , H V c o n tr o l, P W M , H S a w , A u to R e g is t r a tio n s e n s e a n d s w it c h i n g , 5 V o lt r e g u la t o r I C 8 0 0 4 H J u n g le I C 5 0 7 , V M a n d I K b u f f e r s S h a d in g , H V c o n t r o l, r e g u la t o r I C 8 0 0 3 H Saw, H p u ls e s h a p e r ,-5 V o lt

+ 1 2 V (A ) -1 2 +5 -5 +11 +9 +22 -2 2

B D b o a r d ( A u t o R e g is t r a tio n ) B D b o a r d ( A u t o R e g is t r a tio n ) O f f M u t e Q 5 4 7 , 9 V o lt r e g u l a t o r I C 5 0 5 T U 5 0 1 , T U 5 0 2 V i d e o P r o c e s s in g , A V U s w it c h C o n v e r g e n c e A m p l if i e r s I C 5 0 0 5 a n d I C 5 0 0 6 C o n v e r g e n c e A m p l if i e r s I C 5 0 0 5 a n d I C 5 0 0 6

+ 11 Volts
The voltage from the winding of T6001/11 and 12 is applied across D6102 through L6103 and L6104. C6122, C6133 and L6110 filter the rectified voltage. This voltage is used on the G board by the regulation and protection circuits and it exits the G board at CN6104/11 to the A board. The +11 volt supply is used on the A board to produce the +9 volt supply.

22

23

T6001 Secondary-2
+7 Volts
The voltage from the winding of T6001/17 and 18 is applied across D6109 through PS6101 and PS6102. C6117, C6126 and L6107 filter the rectified voltage. The voltage is used on the G board by the protection circuit and exits the G board at CN6104/4 and 5. The +7 volt supply is used to produce three other voltages on the A board. They are Def +5 volts, +5 volts and +3.3 volts.

Distribution
The table below shows the circuits that are powered by the voltages previously discussed:
N am e +7 D ef +5 +5 C ir c u its D e f + 5 V r e g u la t o r I C 5 0 3 , + 5 V r e g u la t o r , 3 . 3 V r e g u la t o r V D S P I C 5 1 2 , H B L K D e la y I C 5 1 7 , ½ IC 5 0 8 , V o u t R e fe re n c e IC 5 0 0 4 , B D b o a rd TU 501, M e m o ry b o a rd H + O d d /E v e n

T U 502, S ync S w it c h IC 5 0 9 , IC 1 3 0 4 F ra m e IC 1 3 0 4 , A /D C o n v e rte r IC 1 3 0 9 , B M b o a rd , B D

+ 3 .3 +135 -1 3 5 +33

3 D C o m b F ilt e r I C 1 3 0 6 , B R b o a r d , B M b o a r d F B T T 8 0 0 3 , L O T T 8 0 0 2 , H V D r iv e , H V o u t P in c u s h io n , H o r iz o n t a l, H V R e g u la t io n TU 501, TU 502

+135 Volts
The voltage from the winding of T6001/8 and 9 is applied across D6104 and D6107. C6114, C6123 and L6106 filter the rectified voltage. The voltage is used on the G board by the protection and regulation circuits and is also used to produce the +33 volt line. It exits the G board at CN6106/1. The center tap of the secondary located at T6001/7 is connected through R6118. As the load draws more current, the voltage across R6118 falls closer to being negative. The OCP circuit monitors this voltage.

-135 Volts
The voltage from the winding of T6001/8 and 9 is applied across D6103 and D6106. C6113, C6127 and L6105 filter the rectified voltage. It exits the G board at CN6106/3.

+33 Volts
The +135 volt line goes through R6111 Current Limiting resistor. On the other side of R6111 is D6110 Zener Diode and C6116. The zener is used to drop the +135 volts down to 33 volts. The voltage exits the G board at CN6104/9.

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Regulation
Overview
The regulation circuit is used to provide a control voltage that determines the oscillating frequency of the IC6003 Oscillator. This is done by using the +11 volt line for this circuit's supply and the +135 volt line as the input.

Operation
The +11 volt line is applied to IC6005/1 and then goes through the internal LED connected between pins 1 and 2 of IC6005. The voltage at IC6005 is applied through R6128 to IC6101/2. IC6101 VCC Controller varies the resistance between IC6101/2 and ground. When the voltage on the +135 volt line goes up, the resistance between IC6101/2 and ground goes down. This causes the current through the internal LED of IC6005 to increase, thereby increasing the brightness of its light. The increase in the brightness of the internal LED causes more current to flow between the C-E junction of the internal transistor inside IC6005. When this transistor conducts harder, it causes more current to flow through D6023 and D6024. This in turn lowers the voltages at IC6003/1 and 6. When these voltages are lowered, the frequency output of IC6003 Oscillator is raised. The oscillator output is at IC6003/9 and 10. When the frequency output is raised, it becomes further from the resonant frequency of the power supply, decreasing the voltage on the +135 volt line.

If the voltage on the +135 volt line should fall, the resistance at IC1601/2 and ground will rise. This causes the current through the internal LED of IC6005 to decrease, which decreases the brightness of the light. The decrease in the brightness causes less current to flow through the C-E junction of the internal transistor inside IC6005. When less current flows through the C-E junction of this transistor, it causes the voltages of IC6003/ 1 and 6 to rise. This in turn causes the frequency output at IC6003/9 and 10 to decrease. This will raise the voltage on the +135 volt line.

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DC Protection
Overview
The RA-4 chassis employs protection for over and under voltage, as well as over current for the +135 volt line. The +22, +19 and +7 volt lines are monitored for low voltage. IC6102 is used to sense over voltage and over current for the +135 volt lines.

+135 Volt Over Current Protection
The over current protection circuit works by monitoring the voltage divider network that consists of R6110, R6103, R6104 and R6118. Essentially we can look at this as the voltage across R6118 since the voltage at IC6102/2 will change with it. This resistor is connected between T601/7 and ground. Since T601/7 is the center tap of the winding that supplies the +135 volt line, any rise in current sourced by that line will cause the voltage across R6118 to lower. This voltage is input into IC6102/2 Inverting input. IC6102/3 Non-inverting input is connected to ground. Therefore, if the current draw on the +135 volt line should cause the voltage at IC6102/2 to become negative, a HIGH will be output at IC6102/1. This HIGH output is applied to the latch circuit and also to IC1009 on the A board for the Self Diagnostic feature. If OCP occurs the Timer LED will flash twice. See the Self-Diagnostics section for more details.

Shut Down
Shut down occurs whenever a condition in the protect circuits causes the Q6103/B to go HIGH. A HIGH on Q6103/B turns it ON, causing it to turn ON Q6102. This drops the drive voltage to Relay Drive Q6104/B, turning it OFF. This removes the ground return path for IC6011 and the unit shuts OFF. During shutdown, the voltage from the RM+5 volt line maintains the latch.

+19, +22, +7 Volt LVP
This protection circuit works by looking at the difference in voltage between the +19, +22 and +7 volt lines and the +11 volt line. If the +19 or +22 volt lines should drop .6 volts below the +11 volt line, this would cause Q6101 to turn ON. If the +7 volt line should drop below 3.5 volts, this would also cause Q6101 to conduct. When Q6101 conducts, it places the +11 volt line on its collector. When this occurs, the latch circuit turns ON and shuts the set down. When this circuit is activated, there is no indication given by the Self Diagnostic circuit. See the Self Diagnostics section for more details.

+135 Volt Over Voltage
The +135 volt line is input to the protection circuit through D6101 and then to a voltage divider consisting of R6101 and R6102. The voltage developed across R6101 is applied to IC6102/5 Non-inverting input. IC6102/6 Inverting input has a voltage applied to it from the voltage divider consisting of R6110, R6103 and R6104. IC6103 is a programmable zener diode, which is used to stabilize the reference voltage at IC6102/6. This voltage is approximately 2.4 volts and will vary about .1 volts since the entire circuit uses a floating ground. If the voltage at IC6102/5 rises above the 2.4-volt reference, then the output at IC6102/7 will go HIGH. This occurs when the +135 volt line is at about +146 volts. This High output is then applied to the latch circuit and to IC1009 on the A board for the Self Diagnostic feature. If OVP occurs, the Timer LED will flash three times. See the Protection Block section for more details.

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PS Troubleshooting
Overview
The key to troubleshooting shutdown problems is to determine if the problem is on the power supply board (G) or one of the other boards in the set. In this section we will give you steps to follow to make this distinction.

because of OVP. If the voltage is below 50VAC, there will not be enough voltage to turn on the power relay and it will chatter. The following table shows the voltages present with the supply fully unloaded and 55 volts AC applied.
M e a s u r e m e n t P o in t C N 6 1 0 6 -1 C N 6 0 1 6 -3 C N 6 1 0 6 -5 C N 6 1 0 6 -6 C N 6 1 0 5 -1 C N 6 1 0 5 -6 C N 6 1 0 4 -4 C N 6 1 0 4 -7 C N 6 1 0 4 -9 N o r m a l V o lta g e +135 -1 3 5 +15 -1 5 +22 -2 2 +7 +11 +33 V o lta g e U n lo a d e d w ith 5 5 V A C a p p lie d +78 -1 3 3 + 9 .9 +12 + 1 0 .7 -1 0 .9 + 5 .6 + 1 0 .3 +31

Troubleshooting
Often shutdown problems occur too quickly for an indication to be given by the self-diagnostics (flashing Timer LED). These are usually caused by the power supply, but not always. The procedure below will guide you towards the resolution of this type of a problem by notifying you if the problem is with the power supply's G board. Symptom: Shutdown - No indication given by self-diagnostics. Timer LED continuously flashes. 1. Unplug CN6106 from the G board. If the set comes up with sound but no picture, replace or repair the D board. If the picture does not come back up, reconnect the plug to CN6106 and move to the next step. 2. Unplug CN6102 from the G board. If the set comes up with no sound, replace or repair the K board. If the sound does not come back up, reconnect the plug to CN6102 and move to the next step. 3. Unplug CN6105 from the G board. If the set comes up, replace the D board or replace IC5005 and IC5006. If it does not, move to the next step. 4. Check fuses PS6101 and PS6103 on the G board. These fuses are for the +7 volt line. If they are open, the set will shut down immediately. If they are OK, move to the next step. 5. We have unplugged all the connectors at this point that can be disconnected and have the set partially run. We can run the set fully unloaded if we lower the AC voltage. First fully unload the G board from the rest of the set by unplugging CN6102, CN6104, CN6105 and CN6106. Now supply 55VAC to the set and press the power button on the remote or the front panel. The power relay will click and the Timer LED will flash continuously. Now you can check the voltages of the power supply using the table below. It is very important that you use 55VAC. If you raise the voltage to 60V, the supply will shut down

Other problems
· More often than not, no sound is caused by a problem with PS6103 and PS6104. Please note this is a very unlikely problem. Shutdown caused by the K board is often indicated by the self-diagnostic circuit, causing the Timer LED to flash eight times. If this type of shutdown occurs, unplug CN6102. If the set operates but there is no sound, replace or repair the K board. If the set displays a symptom of no sub deflection, fuses PS6105 and PS6106 on the G board should be checked.

·

L o c a tio n C N 6 1 0 2 /2 a n d 3 C N 6 1 0 2 /7 a n d 8 C N 6 1 0 4 /2 C N 6 1 0 4 /4 a n d 5 C N 6 1 0 4 /7 C N 6 1 0 4 /9 C N 6 1 0 5 /1

N o r m a l V o lta g e - 1 9 V o lt s + 1 9 V o lt s + 1 5 V o lt s + 7 V o lt s + 1 1 V o lt s + 3 3 V o lt s + 2 2 V o lt s

L o c a tio n C N 6 1 0 5 /3 C N 6 1 0 5 /4 C N 6 1 0 5 /1 2 C N 6 1 0 6 /1 C N 6 1 0 6 /3 C N 6 1 0 6 /5 C N 6 1 0 6 /6

N o r m a l V o lta g e + 1 5 V o lt s - 1 5 V o lt s - 2 2 V o lt s + 1 3 5 V o lt s - 1 3 5 V o lt s + 1 5 V o lt s - 1 5 V o lt s

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Protection Block
Overview
The RA-4 chassis employs a Self-Diagnostic system that uses the Timer LED and an on screen menu to help indicate where the problem with the set has occurred. Generally you will have to use the flashing LEDs since the set will be shut down. In order to turn the set off once shutdown has occurred, AC power must be disconnected.

The number of times the LED blinks may correspond to that shown in the following table:
Diagnosis Item ·Power not ON +B OCP detection +B OVP detection V detection AKB detection H detection HV abnormality detection Audio abnormality detection WDT (Syscon) Standby/ sleep lamp, Number of Blinks Not lit LED blinks 2 times LED blinks 3 times LED blinks 4 times LED blinks 5 times LED blinks 6 times LED blinks 7 times LED blinks 8 times LED blinks 9 times Self-diagnosis screen display, Diagnosis Item Results 2 : +B OCP 3 : +B OVP 4 : V STOP 5 : AKB 6 : H STOP 7 : HV 8 : AUDIO 9 : WDT XX XX XX XX XX XX XX XX

Diagnostic Indication
When a problem occurs that causes shutdown, the Timer LED may blink in a pattern as shown below:
< FRONT PANEL >

* : XX the range of values for number of operations is 00-99.
and the number remains at 99.

For 99 or higher there is no count up

·EXAMPLE · +B overcurrent · +B overvoltage

If the problem is intermittent and you can get the set to operate, you can display a menu showing the number of times failures have occurred. This is done by pressing the following sequence of buttons on the remote. Display Channel 5 Vol - Power The display will look as follows.

TIMER/STANDBY indicator

· Vertical deflection stop

SELF CHECK

2 times 3 times 4 times
Lamp ON : 0.3 seconds Lamp OFF : 0.3 seconds Lamp OFF : 3.0 seconds

2 : +B OCP 3 : +B OVP 4 : V STOP 5 : AKB 6 : H STOP 7 : HV 8 : AUDIO 9 : WDT

XX XX XX XX XX XX XX XX

2 : +B OCP

XX

XX the range of values for number of operations is 00-99. For 99 or higher there is no count up Diagnosis and the numberremainsat 99. Results

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This display can be cleared by pressing 8 and Enter in this mode. There may be situations when the diagnostic system will not work. These situations generally occur when there are power supply problems with the set. When this occurs, the LED will blink continuously at .3 second intervals. More information on troubleshooting these problems will be covered in the power supply section. Keep in mind that other power supply problems could cause a false indication to be given by the Self-Diagnostic section. In addition to sending a signal to the OSD processor, all of these protect lines are connected to the power supply latch on the G board, except for AKB and HV. This means that if there is a protect condition indicated by any circuit except AKB or HV, the set will shut down. When the set shuts down, the Timer LED will blink as stated previously. The set must be unplugged before you can attempt to operate it when a shutdown occurs. There is also an additional LVP circuit on the G board that will not be indicated when a failure occurs. This is due to a problem in this area that causes a number of dilemmas and usually occurs too quickly for an indication to be given. When there is a failure in this area, the Timer LED will flash continuously every .3 seconds.

Circuit Description
All of the circuits that can be indicated by the self-diagnostic have an input to IC1009 OSD CPU, except for the AKB circuit. The indication from AKB is sent over the I²C data lines to IC1008 Main CPU. This data is then sent to IC1009 OSD CPU to be displayed. These indicators are from protection circuits, which will be discussed in more detail in the individual circuit descriptions. They all output a HIGH when they are activated. When a failure is received from one of the circuits, it is stored in IC1007 NVM. This can be helpful when problems are intermittent. Keep in mind that failures might not always indicate the correct circuit. For example, if there is an intermittent HV failure, the indication could be displayed as AKB failure.

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Reset
Overview
There are two reset circuits in the RA-4 chassis. The first reset occurs at initial plug-in, and the second each time the set is powered ON. The initial plug-in reset only resets IC1008 Main CPU. All other ICs that need resetting are reset each time the set is turned ON.

Power ON Reset
When the set is powered ON, there is a LOW going reset pulse sent from IC1008/45 O RSTCTL to IC1009/30 I Reset that resets IC1009 OSD CPU. This reset pulse is also sent to Q1015 Inverter. Q1015 inverts this pulse to a HIGH going reset pulse. It is then distributed to other parts of the set that need resetting. This reset pulse is sent to CN518/18, which is connected to the BM board, and CN522/10, which is connected to the BD board. It also goes to Q1359 Inverter where it is inverted and then sent to IC1306/57 RST B. IC1306 is the 3D Comb Filter. Once this reset has occurred and the set is operating, timing for the I²C bus is set by the VP pulse, which is input to IC1008/25 and IC1009, as well as the other CPU's in the set. This pulse allows synchronization of the data. Once it is received, there will always be activity present on the M and B I²C busses. One "bug" that may be encountered, although very rarely, has to do with reset and S-Link. You may experience a problem since IC1009 OSD CPU is not reset at initial plug-in and the S-Link signal is input to IC1009 OSD CPU. If an S-Link power up signal is sent to the set after it was unplugged and then plugged back in, but before it was turned ON, the set may not respond to the S-Link signal. However if the set was unplugged, re-plugged and turned on at least once, this will not occur.

Initial Reset
When the set is plugged-in, Standby +5 volts is developed on the G board. This voltage is sent to the A board from CN6101 to CN505. This voltage is called RM+5 on the G board and ST-5V on the A board. It is then applied to IC1008 Main CPU and IC1010 Reset. The purpose of IC1010 Reset is to hold the reset line low until the voltage on the ST-5V line reaches a threshold around 4.3 volts. When this threshold is reached, IC1010/4 is released from ground and current flows through pull-up resistor R1117 and R1126. In reset, IC1008/9 I Reset is held low until C1033 charges. C1034 and C1036 are used to filter out any noise or spikes that may occur on the reset line. IC1008 Main CPU will begin to function after reset occurs. After IC1008 Main CPU is reset, the data is read from IC1007 NVM and stored in its own internal RAM. This data contains information on such things as global video settings, video mode presets and user settings, etc. It does not contain the data for Registration or MID settings. After this data is read, the data and clock lines will be high with periodic low going pulses. The CPU is now awaiting further instructions. This B I²C bus is the only active bus when the unit is in standby mode. While the set is running, it will have the same data present as the Main or M I²C bus. If the reset line is held LOW for some reason, the set would appear to be completely dead. X1001 and X1002 would continue to oscillate. IC1008/ 38 and 39 are only active when Closed Caption is selected. These pins are for CCD OSD horizontal positioning and will have a 12 MHz signal on them when closed captioning is ON. IC1008/48 B Data and IC1008/50 B Clk would be HIGH with no activity on them. You would normally always see some activity on these lines.

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System Block Diagram
Overview
This section discusses the System Block for the RA-4 chassis and will show the four different I²C busses. The B bus is active during standby. The M bus is the main bus and controls most of the set. The P bus is part of the auto-registration circuit and controls this circuit's functions. Finally, the MID bus controls the MID functions such as PIP and Twin-View. The diagram also shows two 3-line busses. IC1009 OSD CPU uses one to communicate with IC1004 OSD Processor. The other bus is used by IC1008 Main CPU to control IC2105 Dolby Processor.

C o n n e c to r o r IC C N 5 1 8 (B M ) C N 5 2 1 (B u s C o n n e c to r) C N 5 2 2 (B D ) IC 5 1 1 V id e o P r o c e s s o r IC 5 1 5 A V S w itc h IC 1 0 0 8 M a in C P U IC 1 3 0 1 S u b C h r o m a IC 1 3 0 5 M a in C h r o m a IC 1 3 0 6 3 D C o m b IC 2 3 0 2 L /R T o n e C o n tr o l IC 2 3 0 3 C /S T o n e C o n tr o l T U 5 0 1 M a in T u n e r TU 502 Sub Tuner IC 5 1 2 V D S P

M SD A 15 10 15 56 32 47 37 37 60 29 29 SD A SD A 26

M SC L 14 11 14 55 31 49 36 36 59 30 30 SC L SC L 30

B (Standby) Bus
The B bus is the only bus that is active in the standby mode. It will have the same data on it as the M bus during regular set operation. There are only three ICs on this bus. They are IC1008 Main CPU, IC1007 NVM and IC1009 OSD CPU. In addition to these ICs, the factory test connector can interrupt this bus. This is so that data can be written right to the NVM during production. It also allows for outside control of the set on the production line. This connector would be the one that the Registration Jig for the RA1 and RA2 chassis' would be connected. That jig is not usable on the RA4 chassis due to the different convergence system.
C o n n e c to r o r IC IC 1 0 0 8 M a in C P U IC 1 0 0 9 O S D C P U IC 1 0 0 7 N V M MSDA 48 50 6 MSCL 50 48 5

P (Auto Registration) Bus
The P data bus handles the operation of the registration circuit. It operates independently of the M bus. There will always be activity on this bus when the set is ON. This is because the IC1703 PJED CPU instructs IC1707 Regi Correction to read data from IC1704 NVM to refresh its internal RAM. These commands are sent every vertical period and it takes approximately 20+ vertical periods to refresh all the data. The reason we refresh so often is due to registration malfunctions that occurred during CRT arcing and ESD tests.

MID Bus
The MID bus is located on the BM board and controls the functions of the MID circuit. Commands are sent from IC1008 Main CPU to IC009 MID CPU, which commands IC010 MID Controller to carry out MID functions. Data is only sent during MID operation.

M (Main) Bus
The I²C bus controls most of the set. There is activity on it at all times when the set is powered ON. Any IC on the bus could cause loading problems. The following table shows which pins on each IC are on the bus. If there is a loading problem, these pins can be lifted from the IC to find the problem.

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Video Path Block
Inputs
The two tuner video outputs along with all video signals that enter the unit, except the Video 5 component input, are input into IC515 A/V Switch. IC515 A/V Switch switches these video signals to three different paths. The first is the main video path, next is the sub video path and last is the select output. The select output is used to send a composite version of an input to an output jack on the rear panel. This is selectable in the setup menu. The default setting is to output the main video.

The outputs from IC1307 YUV Switch are then input to the BR board (DRC) and the BM board (MID). The BR board outputs signals that are the main video signal and these outputs are input to IC511 Video Processor. The BM board is used for PIP and Twin View functions.

Sub-Video
The sub-video path is used to carry sub-video to the BM board where it is converted for PIP and Twin-View functions. If a composite signal is input to IC515 A/V Switch, it would be output to CM501 Glass Comb Filter and then input back to IC515 A/V Switch as Y and C. If the signal were an S Video input, it would pass directly to the Y and C outputs of IC515 A/V Switch. The C signal is input to IC1301 Sub Chroma Decoder while the Y signal is input to IC1302 Sub YUV Switch and then switched to IC1301 Sub Chroma Decoder. IC1301 Sub Chroma Decoder takes the Y and C input signals and converts these signals to component video. These sub Y, U and V signals are then input to IC1302 Sub YUV Switch. IC1302 Sub YUV Switch is used to select between the sub YUV inputs and the YUV input from the Video 5 component input. It also mixes in the Sub-video OSD, which comes from the BM board, into the sub YUV signal. The output of IC1302 Sub YUV Switch is output as YUV into the BM board for use with PIP and Twin View functions. The signals from the BM board are input to IC511 Video Processor.

Main Video
The main video path is used to carry composite or Y/C (S Video) to IC1306, the 3D Comb Filter. If a composite signal is used, it is looped out of and back into IC515 A/V Switch, then back out to IC1306 3D Comb Filter. If an S Video input is used, then the Y signal is looped out and then back into IC515 A/V Switch along the same path as the composite input. It then goes to IC1306, 3D Comb Filter. The C signal is output from IC515 A/V Switch to IC1306, 3D Comb Filter. IC1306 3D Comb Filter is used to separate Y and C signals from the composite signal input, and also performs some of the necessary noise reduction and video processing adjustments. If a Y/C signal is input, then IC1306 3D Comb Filter will just perform its noise reduction and video processing functions. The C signal is output to IC1305 Main Chroma Decoder. The Y signal is output to IC1307 YUV Switch where it is switched though to IC1305 Main Chroma Decoder. IC1305 Main Chroma Decoder takes the Y and C input signals and converts these signals to component video. Component video consists of Y, B-Y and R-Y. These signals are also known as Y, U and V and Y, Pb and Pr. In this book we will refer to these signals as Y, U and V. These main Y, U and V signals are then input to IC1307 YUV Switch. IC1307 YUV Switch switches between the main YUV signals and the YUV signal from Video 5 component input. It also mixes in the Closed Caption Data from IC1008 Main CPU. The CCD signal is input as a RGB signal and matrixed to be output as part of the main YUV signal.

IC511 Video Processor
The IC511 Video Processor is used to switch or mix in the appropriate signals among its many functions. These signals are the main YUV, sub YUV, OSD RGB and PJED OSD RGB signals. These signals are converted to R, G and B to be output to the video amplifiers on each of the C boards.

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Input Switching
Overview
The two tuners' video outputs, along with all video signals that enter the unit except the Video 5 component input, are input to IC515 A/V Switch. In accordance with commands received from IC1008 Main CPU, IC515 A/V Switch switches these video signals to three different paths. The first is the main video path, second is the sub video path and third is the select output.

identical buffers before being input to IC515 A/V Switch. In addition, audio is input to IC515 A/V Switch from each tuner. The tuners are not retuned for the audio swap function.

Outputs
Main Video
IC1008 Main CPU determines what input will be switched to each output by interpreting the customer's input and sending commands to IC515 A/V Switch for proper execution. Regardless of which input is selected for the main picture, it will follow the following path: The composite video or Y signal will be output from IC515/ 53 V Out to Q533 Buffer. It is then input to IC515/49 Y In and switched through IC515 A/V Switch to be output at IC515/56 Y Out. The main composite or Y signal is then sent to the main Y buffer before being input to IC1309. IC1309 is an A/D Converter that will digitize the composite or Y signal for input to the 3D Comb Filter. If an S video input is selected, then the C signal will be output at IC515/58 C Out. It is input to the main C buffer before being input to IC1306/96. IC1306 is the 3D Comb Filter.

Inputs
The five video inputs each have separate composite and S Video inputs and all are contained in one package as shown by J505 in the related drawing. Each package also contains left and right audio inputs. All of these jacks input to IC515 A/V Switch where they are switched to the appropriate parts of the circuit by I²C data from IC1008 Main CPU (not shown). IC515 A/V Switch is able to determine if the S video input is being used because of an internal switch in the S video jack. This switch is connected to a voltage divider that is connected to the S Switch input for each of the 5-video inputs. If there were an S video source connected, then the S SW input would be LOW. This causes the internal switch in IC515 A/V Switch to allow the S video input to be passed to the Y and C outputs. If there is nothing plugged in to the S video jack, the voltage on the S Switch line will be 2.5 volts. The operation of the Video 5 circuit is somewhat different because it also has component video input. There is a switch on the Pr input that goes to an additional circuit that places five volts on the S switch line. No video will pass to the Y and C outputs when a cable is plugged in to the Pr input. This will be discussed further in the YUV Switch section. In addition to the 5-video inputs, there are also two tuner inputs. These tuners are all the same type so that this set may have the audio swap function when using PIP features. The sub tuner will never produce the main picture. If a picture swap takes place when using PIP, the tuners will be re-tuned. The main and sub tuner's video signals each pass through

Sub Video
If a composite sub video input is selected, it is output at IC515/42 Sub V Out and then sent to CM501/4 Glass Comb Filter. CM501 Glass Comb Filter is used to separate the Y signal from the chroma in the composite sub video signal. The Y signal is output CM501/1 and input to IC515/38 Sub Y In. The composite signal is also input to the base of Q548, which uses L523 and C643 and C639 to filter out the 3.58 MHz chroma signal. The signal is then input to IC515/40 Sub C In. The sub Y and C signals are output from IC515/45 and 47 respectively. If an S video signal is input, the signals will be output directly at IC515/45 and 47.

Select Out
The select out outputs one of the input signals as composite video from IC515/34, along with audio from IC515/34 and 36. The selected output is determined using the setup menu. These signals leave the set at J502.

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Main Y and C Buffers
Overview
The purpose of the Y and C buffers is to pass the signal from the input switching circuit to the 3D Comb Filter. While performing this, the circuit filters out unwanted frequencies above 7 MHz. In addition to these functions, this circuit also separates the horizontal and vertical sync from the Y or composite video signal.

C Buffer
The C signal is only present when an S video input is used. The C signal is passed through Q536, which is the output buffer for the input switching circuit. It then goes to Q1345, which provides further buffering for the signal before it enters FL1302. The signal enters FL1302/2 and exits FL1302/3. FL1302 filters out all unwanted signals above 7 MHz. After being filtered, the signal goes through another buffer, Q1347. The signal exits Q1347/E and is sent to Q1346/B. Q1346 provides additional buffering for the signal, which is then sent through C1433 and sent to IC1306 3D Comb Filter.

Y Buffer
The Y or composite signal is passed through Q532, which is the output buffer for the input switching circuit. It then goes to Q1340, which provides further buffering for the signal before it enters FL1301. The signal enters FL1301/2 and exits FL1301/3. FL1301 filters out all unwanted signals above 7 MHz. After being filtered, the signal goes through another buffer, Q1342. The signal exits Q1342/E and is split to Q1344/B and Q1334/B. Q1344 provides additional buffering for the signal, which is then sent through C1491 and to IC1309 ADC. If you try to probe Q1344/ B with a scope, you will load the signal and the picture will become distorted. Q1334 is the input to the sync separator circuit.

Sync Separator
Q1334 is the input to a differential amplifier that consists of Q1334 and Q1339 and their associated components. While Q1334/B has the Y or composite signal input to it, Q1339/B is set to a DC reference level of 3.9 volts. The result of these inputs, which is output at Q1339/C, is that only the sync signals are amplified since they are below the threshold. The signal leaving Q1339/C contains vertical and horizontal sync pulses. This signal is applied to Q1337, which acts as a buffer. Next, the signal is applied to Q1341, which amplifies and inverts the sync signals. Negative going vertical and horizontal sync signals are output from Q1341/C. This signal is then sent to IC1306 3D Comb Filter.

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3D Comb Filter
Overview
The 3D Comb Filter is used to separate the Y and C signals in a composite video signal. In this section we will discuss what a 3D Comb Filter is and why we need to use one. In addition we will discuss the comb filter circuit in the RA-4 chassis.

frame 20, we would compare it not only to line 139 and 141 in frame 20, but also with line 140 in frames 19 and 21. This type of processing requires a great deal of memory since it must be capable of storing two full frames of video for the constant comparisons that are occurring. One problem with a full 3D-comb filter system is motion. Motion in the picture between frames can cause some unwanted artifacts. Therefore, the 3D comb filter senses motion in the frames. If no motion is detected, then the line is processed in the 3D process described above. This is referred to as interframe processing. When there is motion in the picture, then the 3D filter reverts back to a 2D filter which uses interline processing. Since many pictures contain both still and moving segments, the 3Dcomb filter has the ability to switch back and forth between interframe and interline processing within a frame. The end result is a picture with higher vertical and horizontal resolution, minimized dot crawl and less noise in the video.

What is a 3D Comb Filter?
History
In order to produce a picture, we need to separate the Y and C signals from the composite video signal. This is necessary to extract the separate R, G and B signals that are needed by the CRT. In the early days of television through the late 70's, a trap filter was used to separate the Y and C signals. This method is now referred to as a 1D filter. This system functioned, but severely limited the resolution of the displayed signal. It also produced unwanted picture artifacts such as dot crawl, which are moving dots at the edge of a black and white transition. A new filter was used in the late 70's. This filter was called a 2D-comb filter because it used the signal in the horizontal and vertical dimensions. It used delay lines to look at two consecutive horizontal lines and compared them. For example, if line 140 could be delayed and then compared to line 141, we could get a much better horizontal resolution and a reduction in dot crawl. However, these filters have trouble with diagonal lines and fine details. These problems result in a loss of vertical resolution. Recently we have overcome these limitations through the use of the 3Dcomb filter. This filter not only uses the horizontal and vertical dimensions, but adds a third dimension - time.

Circuit Description
When the set is first powered on, a pulse from Q1359/C resets IC1306 3D Comb Filter. Q1359 inverts the pulse sent by Q1015, the main reset transistor. This resets all the registers and clears memory so processing can begin. Next, using the I²C data from IC1008 Main CPU, IC1306 3D Comb Filter sets the levels of various adjustments. Examples of these adjustments are YNRL and CNRL. They may need to be adjusted as per Service Bulletin 378 located in the back of the book. IC1309 8-Bit A/D Converter Before the composite signal is input to IC1306 3D Comb Filter, IC1309 ADC first digitizes it. The composite video signal is input at IC1309/4 from the Y buffer circuit. In addition to the video signal input, IC1309 ADC needs a clock and clamp pulse input. The clock input is a 4fsc (14.28 MHz) sine wave signal, which is sent from IC1309/75 ALTF to IC1309/24 CLK. The clamp pulse is sent from IC1306/61 to IC1309/6 PCL. This signal is at the H rate. The RC network connected to IC1309/1, 7 and 10 is used to set the bias for the clamp circuit. The digital output from IC1309 ADC is output from pins 13 ­ 17 and 20 ­ 22 to IC1306 3D Comb Filter.

3D Comb Filter
As mentioned above, the third dimension in a 3D-comb filter is time. This means that not only do we compare the line above or below a horizontal line, but we also compare that line to the corresponding line in the frame before and after it. This means that if we were processing line 140 in

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IC1306 3D Comb Filter The data from IC1309 ADC is input to IC1306/67-74 DYC02 ­ DYC09. The DYC00 ­ 01 inputs are grounded through resistors. Timing is set up for these inputs by IC1306/76 CSI, the composite sync input, and also by IC1306/50 FSCI. The input at IC1306/76 is the composite sync input from the main Y buffer and it controls the timing g