Training Manual KDP-51WS550. AX-1 Chassis KDP-57WS550 KDP-65WS550. Diagnostics and Troubleshooting. Course: TVP-16

Transcription

1 Training Manual KDP-51WS550 AX-1 Chassis Models: KDP-51WS550 KDP-57WS550 KDP-65WS550 Diagnostics and Troubleshooting Course: TVP-16

2 Table of Contents 1. AX-1 chassis PCB Interconnections and Functional Descriptions...1 Overview New Features...5 Manual Convergence... 5 Digital Visual Interface (DVI)... 5 Q-Box AX-1 Chassis Power Supplies...10 Overall Block Diagram Standby Power Supply and Power ON Circuit.. 11 Q-Box, Primary and High Voltage Power Supplies AX-1 Protection Circuits...18 AX-1 Protection Circuits Overall Block Diagram AX-1 Protection Circuit Schematic Diagrams AX-1 Video Processing...9 AX-1 Acceptable Formats... 9 Simplified Main, Sub and OSD Video Path... 9 Troubleshooting AX-1 System Control Circuits...36 Overview AX-1 Deflection Circuits...38 AX-1 Vertical Deflection Circuit AX-1 Horizontal Deflection Circuit AX-1 Audio Circuit...41 AX-1 Audio Block Diagram AX-1 Service Mode and Adjustments...43 Entering Service Mode and Sequence of Adjustments... 43

3 Overview 1. AX-1 Chasis PCB Interconnections and Functional Descriptions Chapter 1 - AX-1 Chassis PCB Interconnections and Functional Descriptions This chapter provides a high-level overall block view of the AX-1 chassis PCB interconnects and the functions performed on each PCB. Figure 1-1 provides a schematic type diagram showing how all the PCBs are interconnected within the complete system. Also shown is a brief list of the functions performed on each PCB. For further details concerning the functions performed on each PCB, reference Table 1-1. This table provides a detailed list of the circuits located on each PCB in the column label circuits. In the column labeled Board Replacement Adjustments is a list of adjustments that must be checked or performed when that particular board is replaced. The column label Comments provides repair comments, such as, if the particular board can be removed from the unit and if the unit will remain powered for troubleshooting, and what symptoms are to be expected when the board is removed. Both Figure 1-1 and Table 1-1 are excellent troubleshooting tools that allow the technician to quickly get to the area they need to be troubleshooting when a defect occurs. QH MEMORY STICK INTERFACE i.link INTERFACE RF DATA DATA Q BOX ATSC TUNER i.link PROCESSING MS PROCESSING A/V INPUTS UA AV SWITCH SIGNAL HB FRONT VIDEO INPUTS DATA UD DVI INTERFACE AUDIO SIGNAL SPEAKERS AC INPUT AC DATA & POWER AD/DC POWER AUDIO AMP MAIN/SUB TUNERS REGULATORS BM MID DRC A/D AC/DC POWER D A AC/DC AUDIO POWER G Q-BOX POWER SUPPLY PRIMARY POWER SUPPLY HV POWER SUPPLY H-OUT V-OUT DATA DC POWER D/C POWER MAIN MICRO PF MICRO VIDEO PROCESSOR AUDIO PROCESSOR VM VELOCITY MODULATION FOCUS BLOCK DRIVE SIGNAL 10V & HEATERS RGB MA CR VIDEO OUT CG VIDEO OUT CB VIDEO OUT SIGNAL HA FRONT BUTTONS IR SENSOR ANTENNA SWITCH RED CRT GREEN CRT BLUE CRT SUB-TUNER MAIN TUNER ATSC TUNER SR FLASH FOCUS SENSORS MAIN H/V DEFLECTION AD DIGITAL REG. PJED CPU PJE DRIVE DATA DS SUB- DEFLECTION SUB- DEFLECTION FIGURE AX-1 OVERALL PCB INTERCONNECTION DIAGRAM TVP /30/04 1

4 A 1. AX-1 Chasis PCB Interconnections and Functional Descriptions Table 1-1 AX-1 Chassis PCB Functional Descriptions Board Circuits Board Replacement Adjustments Field Repairable AD NOT Field Repairable BM NOT Field Repairable C Field Repairable D Field Repairable A/C Input AC Relay Zero Protect STBY 5V PS +9V Reg. +3.3V Reg. +5V Reg. Main & Sub. Tuners Audio Amp. PJED Digital REGI. -5V Reg. +3.3V Reg. AD-DRC MID-XA A/D SRAM +1.8V Reg. +.5V Reg s CR, CG, CB RGB Drive H & V Drive Pin Cushion HV-Power Supply Pri.-Power Supply Audio +/- 14V +10V +1V Reg. +/-15V (Pri) +/-17V +33V +135V +/-15V (T500 Vert.) Heater (T500) Write PJED service data Touch-up Registration Main Picture Contrast, Color, and Hue Size & Geometry Check G Check Electrical Focus Check Hold- Down Comments AC Rect. (D6005) feeds Q-Box, Primary and HV Power Supplies Can be disconnected. Unit remains powered. With total misconvergence displayed. Can be disconnected. Unit remains powered with No Audio & Video Can be disconnected. Unit remains powered with no video Cannot be disconnected. Unit will not be powered ON. Two relay clicks can be heard (AC Relay ON and then OFF). No selfdiagnostic Stdby/Timer LED flash sequence.

5 1. AX-1 Chasis PCB Interconnections and Functional Descriptions D Field Repairable (Cont.) DS Field Repairable G Field Repairable HA Field Repairable HB Field Repairable QH NOT Field Repairable MA NOT Field Repairable Protection Circuits HV Protect HD Drive Protect Beam Current Protect +135 OVP/OCP Sub- Deflection Drive Amps Q-Box Power Supply +9V +5V Reg Key Input LED IR Sensor Front Video Input I-Link Input Memory Stick Interface Board Main Micro PF Micro Video Processor CRT RGB Drive Audio Processor 5V Reg. 3.3V Reg. Size & Geometry Check G Check Electrical Focus Check Hold- Down Touch-up Registration Main &Sub Contrast Color & Hue S-Lin White Balance Color Balance Sub Bright Write A0-Main Data Write A-PF Data Cannot be disconnected. Unit will not be powered ON. Two relay clicks can be heard (AC Relay ON and then OFF). No selfdiagnostic Stdby/Timer LED flash sequence. Can be disconnected. Unit will remain powered. With total misconvergence displayed. Cannot be completely disconnected because it supplies the Primary Supply with DC Start Voltage (PRI-VCC). Can be Unloaded (disconnect Secondary voltages). Can be disconnected. Unit will remain powered. Can be disconnected. Unit will remain powered. Can be disconnected. Unit will remain powered. Cannot be disconnected. Q-Box Module 3 Can be

6 1. AX-1 Chasis PCB Interconnections and Functional Descriptions Q-Box Module NOT Field Repairable ATSC Tuner QM Brd Can be disconnected. Unit will remain powered. QT Brd QI Brd I-Link Processing Memory Stick Processing SR NOT Field Repairable Flash Focus Sensor Can be disconnected. With no Flash Focus function. UA Field Repairable A/V Switch Terminal board Sub-Video Comb Filter Sub Picture Contrast, Color, and Hue Can be disconnected. Unit will remain powered with no video UD NOT Field Repairable DVI Decode 3.3V Reg..5V Reg. Can be disconnected. Unit will remain powered. VM Field Repairable Velocity Modulation Can be disconnected. Unit will remain powered. 4

7 Manual Convergence Chapter - New Features Full/Normal Move + + Select + + End:Menu + + FIGURE -1 - MANUAL CONVERGENCE PATTERN 5. New Features This feature allows the end-user to make point-by-point (Fine) convergence (ref. Figure -1) adjustment using the remote control. Before this feature can be accessed, the Flash Focus feature must be performed. The Flash Focus does not set the convergence settings back to factory settings; this is performed through the Reset function. There is no USER copy function so the end-user must make their adjustments in each screen mode (Full/ Normal, Zoom, Wide Zoom, Memory Stick/High Definition inputs). For optimal adjustment, the following pre-adjustment steps are recommended: Allow the unit to warm up for 30 minutes before adjustment. Set the Mode to Pro or Movie. Lower Picture Level (eliminate any flaring along cross edges). Stand back approximately three to five feet when making adjustment. Note: Press reset to set Mode and Picture back to original settings. Note: If AC power is removed, Flash Focus must be performed again to access Manual Convergence. Digital Visual Interface (DVI) Introduction As the digital display technology (e.g. Plasma and LCD) grows, so does the need to replace the present analog HD component connection between external digital device (e.g. Digital TV/Satellite Receiver) and the HDTV set. The issue is the inherent picture quality problems caused by Digital-to Analog (D/A) and Analog-to- Digital (A/D) conversion processes. For example, if you have a digital Plasma Display HDTV and a Digital TV/Satellite Receiver, the digital video signal in the Digital TV/Satellite Receiver must be converted to an analog component video signal and then sent to the HDTV where it must be converted back to a digital signal video to drive the Plasma display. Because of the two video signals conversion steps and the possible analog signal loss across the connection between the HDTV and the Digital TV/Satellite Receiver, the picture quality will suffer. Even with an analog CRT the Digital TV/Satellite Receiver, video signal must go through D/A conversion, which can adversely affect picture quality.

8 . New Features The resolution to this dilemma is the creation of a complete end-to-end standard digital video interface, ala DVI. The DVI interface is a high-speed digital video interface allowing uncompressed high-definition content to be passed to another DVI equipped device such as an HDTV set. DVI is the only digital interface capable of accommodating uncompressed digital data such as HD video. DVI also has the bandwidth to support higher audio fidelity. DVI has a bandwidth of up to 5 Gigabits/sec, which is more then enough to accommodate an uncompressed HD video transmission typically requiring. Gigabits/sec bandwidth. DVI Connector and Decoding Block Ref. Figure - The DVI Molex connector and Decoding circuitry for the AX-1 chassis are located on the UD-Board (NOTE: This board is NOT field repairable). Figure - shows a block diagram for the UD-Board. The DVI signal (from a Digital TV/Satellite Receiver) is received at the 4-pin Molex connector CN7001. There are three serial data differential channels RX0+/RX0-, RX1+/RX1-, RX+/RX- and one reference clock differential channel RXC+/ RXC-. IC7001 NVM is also connected to the external device through the SDA and SCL (IC) bus. IC7001 stores the EDID (Extended Display Identification Data). EDID is sent to inform the STB or external digital device of the TV s identity and capabilities. HDCP is an Authentication protocol between the external digital device (transmitter) and the TV (receiver) that affirms to the transmitter that the receiver is authorized to receive the protected digital video information. CN 7001/pin 14 (5V) is supplied from the external digital device to power IC7001 (NVM) so EDID can be sent when the TV set is OFF. If the TV set is ON, IC7001 will receive 5V from CN700 through D7001. CN7001/pin 16 is the Hot Plug Detect pin (HPD). The TV set supplies 5V to the external digital device to verify proper connection between the two devices. CONNECTOR R x - R x + R x 1 Ṟ x 1+ R x 0+ R x C- SDA R x 0- R x C+ SCL X MHz V X700 1MHz 3.3V.5V 94 IC7004 DVI-DECODER 95 3 IC7005 MCU SDA, SCL 5V 5V SDA, SCL EDID IC7001 NVM COMPONENT OUT 6 IC7006 NVM HDCP 5V 3.3V REG.5V REG 5V HPD D V.5V FIGURE - - UD BOARD BLOCK (DVI DECODER) 5V CN7001 4P MOLEX CONNECTOR R701 10kHz CN304/ PIN 1 5V TO CN700/ PIN 1 (5V) CN Y PB PR SET-UP MUTE VGA RESET 5V TVP16.- 1/30/04

9 . New Features The DVI Decoder, IC7004 receives the three channels of digital video data and outputs analog component video (Y, PB, PR) to CN700/pins 10, 8 and 6 respectively. Q-Box The Q-Box processes ATSC (off-the-air digital broadcast) broadcast, Memory Stick and I-Link signals. The boards included in the Q-Box are the QM, QI and QT. The QM performs all Q-Module video and audio processing. The QI board is the I-Link interface and the QT is the off-the-air or terrestrial (from antenna switch) signal interface. The Memory Stick feature uses an external interface board QH, which is connected to the Q-Box via USB cable. The Q-Box outputs the 1080i signal format for all selected inputs. The Q-Box is replaced as an assembly (including QM, QI, and QT boards) if found defective. The following text and diagrams will help in troubleshooting and determine a possible defective Q-Box. Figure - 3 is a block diagram showing all the external connections to the Q-Box. i.link FRONT i.link REAR i.link REAR QI i.link QT ATSC TUNER RF FROM ANT.SWITCH BOARD BOARD MEMORY STICK INPUT DIGITAL AUDIO OUT REAR INTERCONNECT USB PCM INTERCONNECT QM MICRO-CONTROL AUDIO/VIDEO PROCESSING CN7300 CN7309 TO UA BOARD ANALOG VIDEO/AUDIO OUT (Y/Pb/PR) (LT & RT) TO MA & G BOARDS POWER/DATA COMMUNICATIONS FIGURE -3 - Q-BOX INTERNAL BLOCK DIAGRAM TVP /30/04 The Q-Box processes the following digital signals: HDTV Terrestrial Signal (RF) Memory Stick Images or Movies I-Link Data The digital signals are processed and D/A converted by the Q-Box processor on the QM board. The Component Video (Y/PB/PR) and Audio (LT/RT) analog signals are then output to the UA (AV Switcher). Digital audio is also output from the Q-Box on the rear (Digital Optical connector) of the unit in PCM/Dolby Digital format. 7

10 . New Features Q-BOX DATA TO Q-BOX MICRO (RESET) 3.V Y PB PR CN7300 POWER & COMMUNICATION RF VIDEO AUDIO NOT USED CN7309 9V 9V 5V DATA FROM Q-BOX MICRO RT LT END VIEW OF Q-BOX FIGURE -4 - Q-BOX CONNECTOR/PIN DETAIL 8

11 . New Features Figure -4 give connector/pin details for viewing Q-Box operating voltages and output signals for troubleshooting. The signals that should be present on the various pins are illustrated in waveforms -5 to -10. The operating DC voltages of 9V and 5V are labeled on the diagram. Note the different scan rates for the Y-Signal in waveforms -7 and -8. These waveforms forms are displayed when receiving a terrestrial signal (RF connector). Waveform -7 is an example of a DTV 480i (Interlaced signal format),, and waveform -8 is an example of a HDTV 70p (progressive scan). NOTE: The 480i and 70p are valid signals for the AX-1 chassis to process and display. The key to display the signals correctly is that the aspect ratio that the broadcaster sends must be correct for the format. For example, the 480i signal should be a 4:3 aspect ratio and the 70p signal should be 16:9 aspect ratio. All HD (1080i, 1080p, 70p) signals should be a 16:9 aspect ratio. Problems occur when the broadcaster sends the HD signals in a 4:3 aspect ratio, which is common at the time of this writing (003). The 70p signal shown in waveform -8 is a HD signal with an aspect ratio of 4:3, which when displayed is cropped inward on left and right sides of the picture (thick black bar areas on both sides). The user cannot adjust the width (make it fill the entire screen) of the picture using Wide Mode adjustment. This is due to the fact the unit is receiving a HD signal (70p), and by industry standards (ref. Table -1) the signal should be broadcast in 16:9 aspect ratio. So, the unit is fooled into thinking it is displaying the picture in 16:9 (maximum width for the unit), but in reality the display is 4:3. Consequently, no compensation can be made. CAUTION: Due to the possibility of screen burn, do not leave the set in the HD 4:3 aspect ratio mode for an extended period of time. Table -1 - Digital Television Standard Display Formats Horizontal Lines Vertical Lines Aspect Ratio Scan Rate :3 60i, 60p, 30p, 4p :9 4:3 60i, 60p, 30p, 4p :9 60p, 30p, 4p :9 60i, 30p, 4p 9

12 Chapter 3 - AX-1 Chassis Power Supplies Overall Block Diagram 3. AX-1 Chassis Power Supplies A BOARD G BOARD PCONT Q610 AC RELAY D6005 AC RECT DC Q-BOX POWER SUPPLY 9V & 5V TO: Q-B0X (QM BOARD) AC IN D613 7V STBY 5V POWER SUPPLY Table 3-1 Primary Power Supply Outputs #1 +/- 14V, -V, +15V, 33V, 9V, 1V # +/- 17V #3 +/- 17V #4 +135V, MAIN 1V STBY 5V TO: MA UA HA DC DC PRIMARY POWER SUPPLY HV POWER SUPPLY DC START VOLTAGE DC START VOLTAGE #1 # #3 #4 HV G FV A DS MA VM BM UA AD UD CR CG CB D BOARD FIGURE POWER SUPPLY OVERALL BLOCK DIAGRAM TVP /30/04 Reference Figure 3-1. The AX-1 chassis power supply system consists of four individual interconnected power supplies, the Standby 5V, Q-Box, Primary and High Voltage (HV) power supplies. The Standby 5V Power Supply provides standby power to the MA board to activate the Main Microprocessor; to the UA board to activate the Control-S circuits; and to the HA board to activate the IR Sensor circuit. All these circuits are initially powered and waiting for an ON command from the ON/OFF button, Remote Control or the Control-S inputs to put the TV in the ON mode. Also, note that the Standby circuit supplies 7V to the AC Relay. This 7V is tapped off prior to the 5V regulator. The Q-Box Power Supply supplies 9V and 5V (in the ON mode) to the Q-Box (the QM board inside the Q- Module) only. The Primary Power Supply supplies various voltages to the A, DS, MA and VM boards directly (in the ON mode). The DC voltage produced by the Primary Power Supply are further distributed to the BM, UA, AD, UD, CR, CG and CB boards through the A, DS, and MA boards as shown on the overall block diagram. The High-Voltage (HV) Power Supply supplies HV to the CRT. It also produces G and FV voltages. Power ON Sequence: Reference Figure 3-1 Once the AC Relay is activated, AC is supplied to all three power supplies via the AC Rectifier. The Q-Box Power Supply is activated first through self-produced DC Start voltage. The Primary Power Supply is activated second by a DC Start voltage, which is produced and supplied by the Q- Box Power Supply. The HV Power Supply is the third and final power supply system activation. The DC Start voltage is produced and supplied by the Primary Power Supply. 10

13 3. AX-1 Chassis Power Supplies When troubleshooting the AX-1 chassis power supply system, keep this sequential DC Start voltage structure in mind. For example, if the HV power supply fails, it may be actually a failure of the Primary Power Supply, which supplies the DC Start voltage to the HV Power Supply, or the problem could be further up in the system in the Q- Box Power Supply, which supplies the DC Start voltage to the Primary Power Supply. Standby Power Supply and Power ON Circuit Standby Power Supply T6101 D C6115 STBY 9.6V ON 8V C IC6109 5V REG STBY 5V MA BRD. (MAIN MICRO IC0001) HA BRD. (IR SENSOR) UA BRD. (CONTROL-S) AC D6114 D6116 D6117 C6116 Q6107 Q6110 Q6111 ZERO_DET D V ON/ OFF REMOTE SIRCS 46 7 MA BOARD IC001 MAIN MICRO A BOARD 69 CN000 CN V D6115 R6111 R6115 D6118 7V Q610 R616 Q6109 D610 C610 + D613 STBY 7V ON 7V RY6000 AC RELAY D6005 AC RECT. TO MAIN, HV & Q BOX POWER SUPPLIES (D BOARD) Reference Figure 3- FIGURE 3- - STANDBY POWER SUPPLY & POWER ON CIRCUIT TVP16.3-1/13/04 The Standby Power Supply is a simple bridge rectifier and filters power supply consisting of bridge rectifier D6113 and filter capacitors C6115 and C6110. This circuit produces the Standby 7V (actually ~ 8V to 9.6V) supply to the 5V regulator IC6109. IC6109 takes the Standby 7V and regulates it down to 5V, which is supplied to the MA board to power the Main Microprocessor IC0001, HA board to power IR Sensor, and UA board to power the Control-S circuit. Also note the protect zener diode D6108 (18V) on the input of the 5V regulator IC6109. Due to its simplistic design, the Standby Power Supply consumes very little current (~ 30mA or ~ 0.4W in standby mode), which satisfies the constraint of less then 1W power consumption in standby mode to be Energy Star complaint. Power ON Circuit Reference Figure 3- The power ON sequence starts with an ON command input from the ON/OFF button (IC0001/pin 46) or the Remote Control (IC0001/pin 7) to the Main Microprocessor IC0001. Once the ON command is received, IC0001/ pin 69 will output a HIGH (3V), which is applied to the base of Q610. Q610 turns ON and goes into saturation and a ground (through Q610) is applied to the AC Relay (RY6000) and the base circuit of Q6109. In standby mode before Q610 is turned ON, Q6107 (kick transistor) is ON and charges C610 to 7V. The 7V is applied to the AC Relay (RY6000). So, once the ground is applied to the relay through Q610, the relay energizes with initial current beginning drawn through C610, which is charged to 7V at that moment. This provides the AC Relay with a good initial power and current source that enables the TV to turn ONn under low or varying AC voltage input sources. The AC voltage input from the home outlet can be as low as 85VAC before the 11

14 3. AX-1 Chassis Power Supplies TV will have problems turning ON. If C610 became defective (open circuit), the AC voltage input can only go as low as 105VAC before erratic TV turn-on function. At the same time the AC Relay is energizing, Q6109 is turning ON. When Q6109 turns ON, it shorts the emitter to base on Q6107 and it turns OFF. Once Q6107 turns OFF, D610 reverse biases, D613 forward biases and applies a HOLD voltage of 7V from the standby power supply to the AC Relay to hold the relay ON in the ON- Mode. Q-Box, Primary and High Voltage Power Supplies Reference Figures 3-3, 3-4, 3-5 All three power supplies use the same converter IC (MCZ3001D) as the heart of their separate switch-mode power supplies, along with two drive MOSFETS and associated components. MCZ3001D contains all the circuitry necessary to function as a switching power supply (except for the Power Switching MOSFETS). It contains: Control Circuitry Oscillator/Oscillator Control Output Driver Transistors 10V Regulator Soft-Start / Delay Shut-Off Timer Over Current Protection Over and Under Voltage Protection The same basic circuit Theory of Operation and Troubleshooting Procedures described in the imminent paragraphs can be applied to all three Power Supply circuits. NOTE: The Q-Box Power Supply component reference numbers will be used in the following circuit description and troubleshooting procedures, just change the component reference numbers to apply the descriptions and procedures to the Primary and HV Power Supplies. There are a few circuit connections that are different between the power supplies, which will be addressed in the text under the appropriate diagram. The only other difference between the power supplies is the operating frequency and some slight voltage readings, which are illustrated on each separate diagram. Switching Power Supply Operation Reference Figure 3-3 for the following circuit description. AC signal is applied to the rectifier block D6005. The AC component is filtered-out by the filter circuit (circuit not shown; located on A-Board). A DC voltage of 96V is produced at the output of the filter circuit. IC6900 Startup Sequence 1) Turn ON Voltage: The 96Vdc from the filter circuit first passes through fusible link resistor R6918 and then is voltage divided by R6907, R6904, R6900 and R6690 down to.5vdc. This voltage is applied to IC6900/pin 1 (Vsense) and IC6900 turns ON. IC6900/pin1 (Vsense) is also used for OVP protection (IC6900/pin 1 > 8V will trigger OVP). ) Internal Circuit Start Voltage: The 96Vdc also passes through voltage dropping resistor R6909, and 79Vdc is applied to IC6900/pin 18. This voltage is used to initially power the internal circuits and begin oscillations. Note that the 96Vdc from R6918 is connected directly to the Drain of Q6900 and serves as the High-side FET power source. Internal circuits initially powered by IC6501/pin 18 Internal drive transistors for the output FETS Q6900 and Q6905 Oscillator Control circuit 1

15 10V regulator (IC6501/pin 10) AX-1 Chassis Power Supplies Note: The 10V output at IC6900/pin 10 passes through D6901 and is then fed back into IC6900/ pin 14, supplying power to the internal driver transistor for the Low & High side output FETS Q6900 and Q ) Output Oscillations: At this point, initial square-wave oscillations of approximately 15KHz are output at IC6900/ pins 16 and 1. Normal operation frequency is approximately 90KHz. 4) Regulator Feedback: The feedback line is connected to the +9V secondary output. Once IC6900 is turned ON and oscillations begin, the secondary winding at T6900/pins 6 and 8 and associated circuitry produces +9V. The +9V is applied to IC6901/pin 1 (Control IC). IC6901 controls the voltage at the PH6900/pin 3, which controls the current output of the optic-coupler PH6900. The amount of current supplied to IC6900/pin depends on how hard PH66900 is turned ON. In normal operation, a voltage of 1.8Vdc (which is proportional to the amount of current) is present at IC6900/pin. The feedback loop is now complete. 5) IC6900 Normal Operating Power Supply (VC1): Produced simultaneously with the oscillator feedback is the operating power source VC1. IC6900/pin 8 (VC1) is produced using a winding on T6900/pin 5. The AC is rectified and filtered, and a DC voltage of 15.6V is applied to IC6900/pin 8. Once the 15.6V is stable, IC6900 s internal control circuit disconnects (internally) the power source at IC6900/pin 18. All IC6900 internal circuits are now powered from IC6900/pin 8. Also, note the second connection at T6900/pin 5 consisting of components R695, D6908 and C6918. This rectifier circuit supplies the Primary Power Supply with its VC1 voltage on IC6400/pin 8 (reference fig. 3-4) Over Current Protection (OCP): ref. Figure 3-3 The current flowing through the switching FETS (Q6900 and Q6901) also passes through C6916, T6900/ pins 1 and 3, R690 and then to ground. The same current also passes through the parallel resistor circuit of R6908 and R6903. This current is directly proportional to the current through the switching FETS. The voltage across R66903 is applied to IC6900/pin 9. The OCP is activated when the voltage at IC6900/pin 9 exceeds 0.V. Over Voltage Protection (OVP) and Under Voltage Protection (UVP): The voltage at IC6900/pin 8 (VC1) is monitored by circuitry inside IC6900 for Under-voltage and Over-voltage conditions. The two conditions are as follows: OVP greater than 33V UVP less than 8V If either of these two conditions occurs at IC6900/pin 8, the unit will go into protection mode. Troubleshooting Tips (ref. Figure 3-3) NOTE: Follow previously discussed IC6900 Startup Sequence. The five steps are in sequential order. NOTE: Use HOT GRND when making measurements on primary side of T6900. This includes all measurements on IC6900. Symptom: Unit goes into protection mode, LED flashes in six times pattern. Check: This indicates either a +5V or +9V shorted condition. Also, there could be a possible open feedback circuit to IC ) Check power supply secondary outputs. Check 5V and 9V conditions at output of the power supply. If the 5V line comes up to proper level and the 9V line goes up to 14V before shut down, a problem exists in the feedback circuit from the 9V output back to IC6900/pin (open circuit)

16 3. AX-1 Chassis Power Supplies If the 9V line comes to proper level but the 5V line is 0V, check for a shorted condition in the circuits the 5V line supplies. ) The Q-Box Power Supply can be safely tested by unloading the +9V and 5V lines. Disconnect CN690. This will completely unload the power supply, but still send necessary feedback to IC6900 for proper power supply operation. 3) If the power supply outputs proper secondary voltages after CN690 is disconnected, suspect a shorted +9V or 5V line 4) If the unit still goes into protection mode after disconnecting CN690, check the following items: D6914, D690, D6903, D6905 and D6904 (15V Zeners) for shorted condition. Check IC6900/pin 8 (B+ OVP) for proper voltage level (within 8V to 33V window). IC6900/pin 15 (this is midpoint for output MOSFETS Q6507 and Q6506). A 10Vpp, 90KHz square-wave should be present. If the waveform pulses four times and stops this indicates that IC6900 is attempting to operate and is most likely good. IC6900 Feedback circuit. The amount of current feedback can be determined by monitoring the voltage drop across R693. The minimum current feedback is 80uA, which is a minimum voltage drop of 37.6mV. In normal operation, this voltage drop is approximately 3mV. If the voltagedrop is below 37.6mV, suspect components in the feedback path e.g. PH650 and IC6503. Reference Figure 3-3 for proper voltages at these components. If no waveform is present when unit is turned ON, then check IC6900/pins 1 and 18 for proper voltages (reference IC6900 Startup Sequence above) before shut down. If these voltages check OK, suspect a defective IC6900. Check IC6900/pin 8 for proper voltage of 4V. This is the voltage used to power IC6900 after initial startup (in the ON Mode). Check IC6900/pin 10 for 10.V. This voltage is initially developed using the 96V at IC6900/pin18 and a voltage regulator circuit inside IC6900. If 10.V is missing, suspect a defective IC6900. Also check voltage at IC6900/pin 14 (Use battery powered DVM for this measurement, and use IC6501/pin 15 (VS) as ground ref.). The voltage at IC6501/pin 14 should be 10V. If the voltage measured at IC6900/pin 14 is incorrect, check D

17 3. AX-1 Chassis Power Supplies A BOARD CN601 1 CN R6918 R6907 R6904 R6900 D6914 R690 D690 15V D6901 C D6903 C G BOARD.5V V-SENSE 1 IC V MCZ 3001D 154V 14 VB 10.3V 10 15V 6 VC TIMER F/B R V 16 VG (H) VS V VG (L) OCP 9 VCI 8 1.8V 15.6V 4.7V 1 + C C6906 R V 11 To PRI. SUPPLY IC6400/PIN8 15V D6905 D V R V Q6900 D6904 (15V) 10Vp-p 90kHz Q6901 R690 R6908 R6903 D6907 D6908 C6918 C6916 R69 C6917 R PH V T V 3 1.4V IC6901 R D6909 R693 D6910 C6919 R693 IC690 C691 5V 9V FIGURE Q-BOX POWER SUPPLY TVP /1/03 15

18 3. AX-1 Chassis Power Supplies A BOARD CN CN R641 D650 C6500 C6501 R /+V -14/-V R649 T6703 TO IC670/ PIN 15 R6406 R6400 R6401 D6411 R640 D V D6401 C D6415 C FROM G BRD. Q-BOX SUPPLY IC6900 TO D BRD. HV SUPPLY IC800.7V V-SENSE 1 IC V MCZ30 01D 146V 14 VB 10.6V 10 VC 15V R6700 NC V VG 16 (H) VS V VG (L) 4.8V 1 6 TIMER OCP 0V 9 F/B VCI 8 1.9V 15.6V 0V D BOARD Grnd L V D C6416 R6701 Q6400 D6406 (15V) 100Vp-p 71kHz 1 Q6401 C6413 R6418 R6417 R6409 R6405 D6410 R PH V V IC D V L6500 L651 D6508 R C651 D6503 D6509 C6503 C6504 IC6501 1V Reg D6511 C6513 L6508 C6514 L6505 L6507 D V 1V +17V -17V MAIN 33V +10V +135V A BOARD IC600 9V REG IC601 5V REG IC60 3.3V REG IC V REG FIGURE AX-1 PRIMARY POWER SUPPLY TVP /9/03 16

19 3. AX-1 Chassis Power Supplies The notable differences between the Primary and Q-box Power Supply circuit description and operation are as follows: No connection on IC6400/pin 18. Remember this was the initial voltage supply to start the IC internal circuits, so the IC itself could produce the running voltage at IC6400/pin 8. But since the voltage at IC6400/pin 8 is supplied by the Q-Box Power Supply, there is no need for a connection at IC6400/pin 18. Slightly different voltage reading around IC6400. Different output signal level and frequency at IC6400/pins 1 and 16 (100Vpp and 71KHz). The feedback line (IC6400/pin ) monitors the +135V line. And obviously the secondary voltages produced. TO IC800/ PIN 15 D8010 C805+ D V + C V 10 D-BOARD R8054 R8055 D8038 R V V-SENSE 1 IC800 R8056.4V MCZ D D 15V 11V 14 VB VC VG (H) 6 TIMER OCP F/B VCI V 17V N/C V D801 R D801 15V 111V VS 15 Q8013 VG 4.8V R (L) D8011 D V 0V D8013 D8014 Q8014 R8051 TO IC8001/PIN 5 PROTECT. L800 C R Vp-p 00KHz R8049 FROM D6530 AC-RECT. 7 6 T8001 HV D R8085 D FV FOCUS FROM PRI. POWER 5 1 ABL SUPPLY T6400/PIN 4 D80 R V 7 R RV V 10.6V.4V R V 3 3 IC R8059 R8010 CONTROL R V PH8003 R8015 IC8004 D8009 BUFFER 15V G SCREEN - + TO ARCING PROTECTION CIRCUIT FIGURE AX-1 HV POWER SUPPLY CIRCUIT TVP /9/03 The notable differences between the High Voltage (HV) and Q-box Power Supply circuit description and operation are as follows: No connection on IC800/pin 18. Remember this was the initial voltage supply to start the IC internal circuits, so the IC itself could produce the running voltage at IC800/pin 8. But since the voltage at IC800/pin 8 is supplied by the Primary Power Supply, there is no need for a connection at IC800/pin 18. Slightly different voltage reading around IC800. Different output signal level and frequency at IC6400/pins 1 and 16 (110Vpp and 00KHz). The feedback line (IC6400/pin ) monitors the HV line (T8001/pin 13). 17

20 Chapter 4 - AX-1 Protection Circuits AX-1 Protection Circuits Overall Block Diagram 4. AX-1 Protection Circuits MA BOARD A BOARD LOW B+ PROT. 5V Q0008 IC0001 MAIN MICRO 6X A BOARD ZERO - DET Q6110 Q6111 Q611 9X AUDIO PROTECT Q005 Q006 Q008 8X HV LVP PROTECT IC X IC000 PF MICRO IC0401 Y/C JUNGLE REGULATORS OVP 3X AC RELAY RY LATCH Q6105 A6108 IC6801 B+ OVP 3X IK PROT. Q8007 X (D) B+ OCP Q6803 X VERTICAL PROTECT IC5101 4X HV PROTECT IC8001 IC800 HV POWER SUPPLY HV CR, CG, CB BOARDS H PROT. (IK PROT 1) Q8008 H PROT. Q50 WHITE BALANCE PROTECT 7X 5X 7X 10X H PROT. (H. PLS) IC X D BOARD FIGURE AX-1 PROTECTION CIRCUITS OVERALL BLOCK TVP /4/03 Figure 4-1 is a basic block diagram illustrating the connections between the protection circuits and Main Micro, PF Micro and Y/C Jungle ICs. Also shown on the diagram are the Standby/Timer LED flash sequences (under each block), which will occur when the particular protection circuit is triggered (e.g. 4X will occur with a vertical deflection failure). Each protection circuit will be discussed in greater detail in coming diagrams. The purpose for each protection circuit is indicated by the name of the particular block. The important thing to note on this diagram is the protection circuits that have a direct connection to the CPU and those that do not. The protection circuits that have a direct connection will produce a more reliable flash sequence, e.g. X, 3X, 4X, 5X, 6X, 7X, 8X, 9X and 10X (as shown in the Diagnostic Test Indicates table in the service manual). The circuits that do not have a direct connection (or designated flash sequence as per the service manual) to the Main Micro or Y/C Jungle are connected in parallel with another circuit and will produce the same flash sequence as that circuit. 18

21 Reference Figure AX-1 Protection Circuits B+ OCP (Q6803) monitors the current draw on the +135V line. If the current should increase due to an excessive load on the +135V line, the Latch will be triggered and shut OFF the AC-Relay. Also note that there is a direct connection from the B+ OCP circuit to IC0001 Main Microprocessor for self-diagnostics indication processing. B+ OVP (IC6801) monitors the +135 voltage level. If an over-voltage condition occurs, the Latch will be triggered and shut OFF the AC-Relay. Also note that there is a direct connection from the B+ OVP circuit to IC0001 Main Microprocessor for self-diagnostics indication processing. IK-Protect 1 (Q8008) monitors the current in the secondary of the FBT using the ABL voltage. If excessive current flows in the FBT secondary, Q8008 is used to mute the video. Q8008 works simultaneously with Q8007, which turns off the AC relay. IK Protect (Q8007) monitors the current in the FBT secondary. If the current increases, Q8007 will disconnect the AC power via IC0001. Note that this circuit is connected in parallel with B+ OCP circuit and will produce a X flash sequence (same as B+ OCP). Q8007 works simultaneously with Q8008, which mutes the video output. V-Protect (IC5101) is the vertical deflection output drive IC. The protection circuit monitors the vertical feedback signal from the VDYs. A feedback pulse is also produced at IC5004/pin 3 when IC5101is working properly and driving the VDYs. If a vertical failure occurs, the feedback pulse is not produced and the vertical feedback is grounded. The video is muted (AC-Relay and Audio remain ON). H-Protect (IC8006) monitors the horizontal deflection output drive. If the horizontal deflection stops, IC8006 will turn-off the HV converter IC800 (this circuit is connected in parallel with IC8001 HV OVP). H-Protect (IC50) monitors the horizontal pulses. If the horizontal deflection stops, so do the horizontal pulses. This circuit will cause the Y/C Jungle (IC0401) to blank the video and also shut off the AC-Relay via the PF and Main microprocessors. HV LVP (IC8004) monitors the HV output. If the HV is LOW, IC8004 detects this condition and the AC power is removed via IC0001. HV OVP (IC8001) monitors the HV level. NOTE: this circuit is on the HOT (or primary) side of the transformer, so use HOT Ground for measurements. If the HV increases, IC8001 will turn off the HV converter IC800. Low B+ Protect (Q0008) monitors the 5V dc level. If the dc level falls below 4.5V, Q314 detects this error and the AC input is disconnected. White Balance Prot. (IC9001, 900, and 9003) on the CR, CG and CB boards are the cathode drive ICs. Each IC produces a separate IK pulse directly proportional to the current in each cathode. The current in each cathode indicates the physical condition of the cathode. Depending on the cathode condition, the set will either increase RGB drive to the cathode or go into IK Protection mode. Zero Detect (Q6110, Q6111, and Q611) are used to monitor the frequency of the AC Input signal at initial unit power-on. The circuit detects the zero-crossing of the AC signa, and times the power-on of the unit to coincide with the zero-crossing eliminating as much as possible initial surge currents that could cause damage to the power supplies. This circuit basically takes the place of the Inrush Relay circuit in previous models. Audio Protect (Q005, Q006, and Q008) monitors the speaker output for a positive (Q006) or negative (Q005) DC voltage. If a DC voltage exists on either output, the circuit will trigger. Regulator Protect monitors the various dc regulator outputs for an over voltage condition. 19

22 AX-1 Protection Circuit Schematic Diagrams 4. AX-1 Protection Circuits Direct Latch/AC-Relay Shut-OFF Circuits (B+ OVP, B+ OCP, IK-Prot and DC Regulator protection) FROM R6118 IC000 P-CONT MA BOARD R6113 Q6105 D6115 R6111 TO AC RELAY RY6000 Q610 TO MA BRD. IC0001 D61 9 CN011 9 CN V C6804 R6814 R681 D BOARD D6803 B+OCP IK_PROT R6816 0V R681 C6803 R6831 Q6803 R6817 R6815 Q V +135V D6805 1V R6805 R80 C801 R61 C6119 D803 5V Q V 0V C8017 FBT PIN 1 (ABL) R613 TO MA BRD. IC0001 R8040 R8039 R8038 R8043 R8030 R807 R8041 R8036 R V D611 CN011 CN5006 D6804 3V 8 8 Q680 A BOARD B+ 0VP IC6801 R6811 R V V R V FROM D V D608 D607 10V D606 D605 6V D604 D V D61 D V REG PROT. IC600 9V REG IC601 5V REG IC60 3.3V REG IC V REG FIGURE 4- - AX-1 LATCH/AC-RELAY SHUT-OFF PROTECTION CIRCUITS TVP16.4-1/13/04 NOTE: In this diagram, B+ OCP and B+ OVP has system designated flash sequences. The IK-PROT and REG-PROT circuits are connected in parallel with the B+ OCP and B+ OVP circuits. When the IK-PROT and REG-PROT trigger, the STBY/TIMER LED will flash X and 3X respectively. B+OCP Protection Circuit (Reference Figure 4-) The current in the +135V line is monitored using R681 and Q6803. R681 is the current sensing resistor. The current in the +135V line flows direct through R681. The voltage drop across R681 in normal operation is very low approximately 0.V. So, the +135V is passed with very little loss in normal operation. The voltage on the left side is essentially equal to the voltage on the right side of R681, and because R681 is connected across the base/emitter junction of Q6803, there is no 0.6V difference across the junction and Q6803 is OFF. When the current in the +135V line begins to increase due to a defect the voltage drop across, R681 will also increase. Because of the increased voltage drop across R681, the voltage on the left side of R681 will remain constant but the voltage on the right side of R681 will decrease. The decreased voltage on the right side is applied to the base of Q6803 through D6805. Once the voltage drop across R681 is large enough to cause a 0.6V difference across Q6803, base/emitter junction Q6803 turns ON. Current now flows through the voltage divider consisting of R6816, R6817 and R6815. The voltage drop across R6815 is applied to the anode of D8005 and then D61 forward biasing both diodes. A high is then applied to the LATCH. The LATCH reduces the voltage at the base of Q610, turning it OFF, which removes the ground to the AC-Relay turning it OFF and therefore shutting OFF the unit. The TV video is muted and the AC relay shuts down and the Stby/Timer LED flashes a X sequence. 0

23 FBT Over Current Protection (IK-Prot 1) (Reference Figure 4-) 4. AX-1 Protection Circuits The secondary current in FBT is monitor by Q8007 at FBT/pin 1 (ABL). The +135V is used as the reference voltage through the resistor voltage divider consisting of R8040, R8039, R8038, R8037, R8043, R8036, and R8035. The combined voltage drop across R8036 and R8035 is used to turn off Q8007 and trigger the protection circuit. In normal operation 0.6V is applied to the base of Q8007 turning it ON and a Low is present at the collector. A High at the collector is needed to activate the protection mode. As the current in the FBT secondary increases the ABL line will pull more and more current through the resistor network of R8035, R8041, and R808. The voltage drop across R8035 will decrease causing the combined voltage drop across R8036 and R8035 to decrease. At the same time the 0.6V at the base of Q8007 is decreasing which turns OFF Q8007. A High will be developed at the collector through pull-up resistor R80, and Zener diode D803 (5.1V) will conduct. D8005 is now forward biased and a High is applied to the Anode of D6803 and D61 causing them to conduct, applying a high to the LATCH circuit. Once the latch is activated, the voltage at the base of Q657 is reduced and it turns OFF, removing the ground path for the AC Relay and it turns OFF. The TV shuts down and the Stby/Timer LED flashes a 7X sequence. B+ OVP (Reference Figure 4-) The voltage level of the +135V line is monitored using IC6801. If the +135V increases at IC6801/pin 1, the voltage at IC6505/pin will decrease. Once IC6505/pin decreases 0.6V (more negative then the collector), Q680 will turn ON. D611 is now forward biased and a High is applied to the LATCH circuit. Once the latch is activated, the voltage at the base of Q657 is reduced, turning it OFF and removing the ground path for the AC Relay, turning it OFF. The TV shuts down and the Stby/Timer LED flashes a 3X sequence. 9V, 5V, 3.3V, and 3.3V DC Regulator OVP Protection (Reference Figure 4-) The 9V, 5V and both 3.3V regulators are protected against any over voltage condition using zener diodes (D607, D605, D603 and D611). If any of the regulate circuits increase above the zener voltage (over voltage condition), the zener will conduct and forward bias the appropriate steering diode (D608, D606, D604 or D61), which in-turn will forward bias the B+ OVP steering diode D611. D611 is now forward biased and a High is applied to the LATCH circuit. Once the latch is activated, the voltage at the base of Q657 is reduced. turning it OFF and removing the ground path for the AC Relay, turning it OFF. The unit shuts down. Note that the regulator protection circuits are connected in parallel with the B+ OVP protection circuit. Consequently, when the regulator protection circuits are activated, they will produce the same Stby/Timer LED 3X flash sequence. 1

24 4. AX-1 Protection Circuits Vertical and IK-Prot 1 Protection Circuits A BOARD MA BOARD HA BOARD STBY 5V AC RELAY RY6501 CN CN CN101 CN0004 IO-SDAT IC000 PF MICRO IC MAIN MICRO 31 D BOARD IC SDA CRT DRIVE H-PROT. V-PROT D8007 D8019 5V 15 CN CN A BOARD 1V Q V + R804 + C8015 C V R8040 R8039 R8038 R8037 R8043 R8031 R8036 R8035 (FBT OCP) CN006 7 CN R8041 FROM FBT/ PIN 1 (ABL) Q5101 C5103 V-DY (-) FEEDBACK CN5015/PIN 3 9V + Q5103 BUFFER R5101 Q510 15V R5110 D V R5106 FIGURE AX-1 VERTICAL AND FBT OCP PROTECTION CIRCUITS 3 FB PLS IC5101 V-DRIVE (VERTICAL DEFLECTION PROTECTION) TVP /14/04 FBT Over Current Protection Circuit (IK Prot. 1) (Reference Figure 4-3) The secondary current in FBT is monitored by Q8008 at FBT/pin 1 (ABL). The +135V is used as the reference voltage through the resistor voltage divider consisting of R8040, R8039, R8038, R8037, R8043, R8036 and R8035. The combined voltage drop across R8036 and R8035 is used to turn off Q8008 and trigger the protection circuit. In normal operation 0.6V is applied to the base of Q8008, turning it ON and a Low is present at the collector. A High at the collector is needed to activate the protection mode. As the current in the FBT secondary increases, the ABL line will pull more and more current through the resistor network of R8035, R8041 and R808. The voltage drop across R8035 will decrease, causing the combined voltage drop across R8036 and R8035 to decrease. At the same time, the 0.6V at the base of Q8008 is decreasing, which turns OFF Q8008. A High will be developed at the collector through pull-up resistor R804 and Zener diode D8019 (5.1V) will conduct. D8007 is now forward biased and a High is applied to IC0401/pin57 (H-Prot), which will blank the video. The unit shuts down by IC0401/pin5 communicating with IC000/pin31 (PF Micro); IC000/pin4 then communicates with IC0001/pin31 (Main Micro), which turns OFF the AC-Relay. The unit video is muted, the AC relay shuts down and the Stby/Timer LED flashes a 7X sequence.

25 Vertical Deflection Protection (V-Prot) (Reference Figure 4-3) 4. AX-1 Protection Circuits The operation of the vertical deflection circuit is monitored using the vertical feedback signal from the VDY (CN5015/pin3) and the feedback pulse developed at IC5004/pin 3 (vertical drive IC). When the vertical circuit is working properly, the vertical feedback signal is fed direct to the Y/C CRT Drive IC0401/pin56 through R046, and the feedback pulse is generated at Vertical Drive IC5101/pin3. If the vertical drive signal IC5101/pin5 (not shown) to the VDY stops due to a defect, the feedback signal (CN5015/ pin3) and feedback pulse (IC5101/pin3) will also stop, and the unit will go into vertical shut down. The feedback pulse circuit applies a hard ground to IC0401/pin56 to ensure that the unit goes into vertical shutdown if a defect occurs in the vertical drive circuit. The vertical feedback pulse is amplitude limited using D5110 (4.7V Zener diode). The pulse passes through buffer Q5103 and is applied to the base of Q510, turning it ON, while applying a Low to the base of Q5101, turning it OFF. With Q5010 OFF, the V-DY feedback will be applied to IC0401/pin 56, indicating proper vertical deflection operation. If the Vertical deflection should cease due to a defect, the feedback pulse at IC5101/pin 3 will not be developed (no pulse through Q5103 buffer), Q510 will turn OFF and Q5101 will turn ON. The V-DY feedback signal will go to ground. IC0401/pin 56 detects the missing V-DY feedback signal and places the unit in vertical shut down. In vertical shut down mode, only the video is muted, the AC power and Audio remain ON and the Stby/ Timer LED flashes a 4X sequence. HV LVP (Low Voltage Protect) Circuit RY6000 AC RELAY 69 HV-PROT. 5 MAIN MICRO IC0001 MA BOARD CN CN CN006 4 CN A BOARD RV V 7 IC V 13 FBT T8001 HV LVP TO HV CONVERTER (IC800) FEEDBACK SIGNAL R8017 R8014 R8015 R8033 0V 7 R V.V R808 D BOARD FIGURE AX-1 HV LOW VOLTAGE PROTECTION CIRCUIT TVP /30/04 3 9V

26 (Reference Figure 4-4) 4. AX-1 Protection Circuits The HV level is monitored through the HV Regulator circuit IC8004. IC8004 and resistor network RV800, R8017, R8014 and R8015 are part of the HV regulation circuit (feedback path for IC800 HV power supply converter). A sample of the HV is output at FBT/pin 13 and is applied to IC8004/pin 5 (Buffer). Approximately 6.5V is produced at IC8004/pin 7, which is then applied to the resistor network (RV800, R8017, R8014 and R8015). Approximately.5V is developed at the junction of R8015 and R8017. R8014 is the feedback path for IC800 (HV Power Supply Converter IC) to keep the HV regulated. R805 is the path for the HV LVP circuit. The voltage at IC8004/pin is directly proportional to the HV; consequently a decrease in HV will cause a decrease in voltage at IC8004/pin. When the.5v at IC8004/pin decreases below the reference voltage.v at IC8006/pin3, a High will be output at IC8004/pin 1 (approximately 14V). Zener diode D807 (3V) will conduct and regulate the voltage applied to IC0001/pin5 to 3V. A high at IC0001/pin5 (HV-Prot) will cause IC0001/pin69 to shut OFF the AC-Relay, turning OFF the unit. The Stby/Timer LED will flash a 10X sequence. AX-1 Excessive HV (HV OVP) and Horizontal Deflection (H-Prot) Protection Circuits D-BOARD (EXCESSIVE HV PROTECTION) Q8004 C8007 D804 6.V R C800 C801 IC8001 0V + 7 A - 0V + 1 NOTE: HOT GROUND SECTION.4V C8006 IC800 HV SWITCHING CONVERTER - B + IC8104 VREF. 1 V-SENSE R8001 Q8003 D V.5V V 1.9V R8016.4V R V FROM T650/PIN 8 Q8014 Q8013 R8046 R805 H DRIVE D807 C8041 Q5001 H-OUT PH FBT T8001 FBT T8001 R807 9V R V 15V 7 IC8006 R8135 TO R8136 HORIZONTAL DEFLECTION YOKE 9V Q5701 C500 BUFFER C5006 C5010 D V TO LOW HV PROTECT REF. FIG. 4-4 FOR DETAIL (HORIZONTAL DEFLECTION PROTECTION) +.V 4.3V R8137 D Vpp 33.75KHz Q570 (BUFFER) 0V 1V Q50 AC RELAY RY6000 MAIN MICRO IC0001 IC000 PF DRIVE IC0401 CRT DRIVE R D505 FIGURE AX-1 EXCESSIVE HV & HORIZONTAL DEFLECTION PROTECTION CIRCUITS TVP /4/03 4

27 Excessive HV Circuit (Reference Figure 4-5) 4. AX-1 Protection Circuits The HV is monitored at FBT/pin 5 using two comparator circuits (A & B) located in IC8001. Comparator A will be triggered when there is a sustained excessive HV (or gradual HV increase), and comparator B will trigger on a momentary (or fast increase) HV spike. Another way to look at these comparators circuits is that they are complementary circuits to each other to ensure shutdown under any excessive HV condition the HV and AC power will be shut OFF. Both comparators receive a sample of the HV from T8001/pin 5, which is input to IC8001/pin 5 and IC8001/pin3. A reference voltage (Vref) of.v is developed at IC8014/pin 3 and applied to IC8001/pins and 6. Once the voltage at either IC8001/pin 5 or 3 increases above the reference voltage due to an excessive HV conditions, a High will be output at either IC8001/pin 7 or 1. The High output will turn ON either Q8004 or Q8003, which will then apply a Low (or ground) to IC800/pin 1 (V-sense) turning the HV power supply converter IC OFF. Drive to the FBT will stop and HV will not be developed. Once the HV power supply is turned OFF, the HV sample at T8001/pin13 is removed. The HV LVP circuit detects the absence of voltage at T8001/pin13, which turns the AC-Relay OFF via IC0001 (Main Micro). The unit shuts down and the Stby/Timer LED flashes a 6X sequence. Horizontal Deflection Protection (Reference Figure 4-5) A sample of the Horizontal drive pulse is taken off the top of C5010. The pulse at this point is amplitude limited using D570 to 15V. The sample pulse is first buffer by Q5701 and Q570 and then applied to comparator IC8006/pin 5 through D8140. Approximately 4.3V is developed at IC8006/pin 5, making it more positive then the reference voltage on IC8006/pin 6 (.V). This condition causes a High (15V) to be produced at the output of the comparator IC8006/pin7. The 15V from IC8006/pin 7 is applied to the cathode side of the LED PH8001/pin, and 15V is also applied to the anode side of the LED PH8001/pin 1. So, the LED is OFF and the collector/emitter junction at PH8001/pins 4 and 3 is open..4v is present at PH8001/pin 4. If the horizontal drive to the deflection yoke were to cease (possible defective H-Out), there would be no sample pulse applied to IC8006/pin 5 and IC8006/pin 5 will go to 0V. This condition will cause IC8006/pin 7 to go Low. This Low is applied to the cathode of the LED PH8001/pin, the LED turns ON and the collector/emitter junction PH8001/pins 3 and 4 conduct, applying ground to IC800/pin 1 (V-Sense). This turns the HV power supply converter IC800 OFF and no drive to the FBT (HV output stops). With no drive to T8001, there will be no output on T8001/pin 13. T8001/pin 13 is connected to IC8004/pin 7 and outputs a low to IC8006/pin. This will cause a high to be output at IC8006/pin 1. This high will cause D808 to break-over, a high will be applied to the latch circuit of Q653 & Q6530 and the AC relay will be shut-off. The horizontal pulse is also applied to Q50, which in normal operation is turned ON, applying a ground to the anode of D505 keeping the protection circuit OFF. If the horizontal deflection stops, Q50 turns OFF and D50 forward biases applying a high the IC0401/pin57. IC0401/pin57 communicates with IC000, which then communicates with IC0001 to shut OFF the AC-Relay. The unit shuts down and the Stby/Timer LED flashes a 10X sequence. 5