Panasonic TC-26LX20 Technical Manual
Lcd high definition tv
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Summary of Contents for Panasonic TC-26LX20
- Page 1 PASC050803TG1 Technical Guide LCD High Definition TV Models, TC-26LX20, TC-32LX20 and Combo Model TC-22LR30 LH-34 Chassis Functional Overview, Circuit Description and Troubleshooting Panasonic Services Company National Training...
- Page 2 "HDMI, the HDMI logo and High-Definition Multimedia Interface are trademarks or registered trademarks of HDMI Licensing LLC." BBE, the BBE logo, Sonic Maximizer and High Definition Sound are registered trademarks or trademarks of BBE Sound, Inc. Copyright © 2005 by Panasonic Services Company All rights reserved. Unauthorized copying and distribution is a violation of law.
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Page 3: Table Of Contents
Table of Contents Objective ........................1 Features ......................... 2 LCD Technology......................2 Dynamic Image Balancing.................... 3 3D Y/C Separation ......................3 LCD High Definition TV Model Differences ..............4 Differences between Models ..................4 Circuit Board Layout..................... 5 TC-22LR30 Circuit Boards.................... 5 Circuit Board Interconnection.................. - Page 4 Standby Power Supply.................... 21 Primary Power Supply..................... 21 Power Supply Operation (TC-32LH, TC-26/32LX20)..........22 Power On Operation of the DC-to- DC converter ..........22 Power Off Operation of the DC-to-DC converter........... 23 Protection of the DC-to-DC converter..............23 AP Board - Secondary Power Supply ..............25 Secondary Voltages ....................
- Page 5 Appendix........................46 Backlighting......................... 46 Inverter Power Supply ....................46 High Voltage Power Supply..................47 Test and Measurement ....................48 Specifications ......................49 Combo Overall Specification ..................49 TV Portion ........................50 DVD Portion ......................... 51...
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Page 6: Objective
Objective This technical guide was prepared with the following objectives in mind: • Provide the servicer with a brief overview of the concepts of operation for new circuits employed in this line of models • Provide drawings with emphasis on the signal path to simplify the task of signal tracing and to locate the cause of a defect •... -
Page 7: Features
Features LCD Technology The LCD AI (Artificial Intelligence) technology incorporated within this model is very similar to that covered in previous LCD models. The Pixel Control IC, in conjunction with the Main Microcontroller IC, located on the DG Board, is responsible for controlling the backlighting and the active matrix display addressing. -
Page 8: Dynamic Image Balancing
Dynamic Image Balancing Enhancements have been made in the LCD AI technology as newer units evolve. This is an example of the improvements made in the luminance distribution in real time. Dynamic Image Enhancement Figure 3 3D Y/C Separation The luminance and chrominance of the composite video signals are separated using a three dimensional Y/C separation circuit commonly known as a Comb Filter. -
Page 9: Lcd High Definition Tv Model Differences
LCD High Definition TV Model Differences Differences between Models The significant differences between models associated with the TC-22LR30 combo unit (TC-26/32LX20 series) can be found in the following areas. CD TV Section The GC3 Global c ore IC series that are used for the Video Signal processing, the Microcontroller, the Video SW, and the Audio SW are same as that of the LCD TV (TC- 26/32LX20). -
Page 10: Circuit Board Layout
Circuit Board Layout C-22LR30 Circui t Boards The TV portion of the combo unit is very similar to that of the TC-26/32LX20 and is omprised of the following boards along with their associated part numbers as shown in this figure. Disassembly of this unit is much easier than the disassembly of the unit covered in the previous online course because the stand or base doesn’t have to be removed for removing the rear cover. -
Page 11: Circuit Board Interconnection
Circuit Board Interconnection his diagram is in tended to provide an overview of the interconnection o f the various circuit boards of the TC-22LR30 LCD Combo Unit. Circuit Board Interconn ection Figure 6 DVD Portion Circuit Board Description Board Name Part Num Description LSEP2171B... -
Page 12: System Control Block
System Control Block The control signals responsible for the overall operation and control of both units are shown in this diagram along with their designated termination points. Main Power switch signal is derived from the power on switch, which is located on the K board. - Page 13 System Control Signals Figure 7...
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Page 14: A Board (Tc-22Lr30)
Circuit Board Description A Board (TC-22LR30) The A board serves as the main board and is comprised of the following: The Video Switch IC3101 is responsible for selectively switching all video inputs (Component, Composite, S-Video and HDMI). The selected input is fed to the DG Board via the connector A1. -
Page 15: H Board (Tc-26/32Lx20)
H Board (TC-26/32LX20) The H Board on models TC-26/32LX20 is comprised of an S - Video and Composite video input connection, two Component video inputs, a DVI audio input and an Audio output connection. This board has been merged onto the A board of the TC-22LR30 Combo unit. -
Page 16: K Board (Tc-22Lr30, Tc-26/32Lx20)
K board (TC-22LR30, TC-26/32LX20) The K board contains the TV ON/Off, Volume, and Channel select buttons, and an additional S-Video and Composite video input connector and headphone jack. It connects to the A board via connector K3. Figure 10... -
Page 17: A Board (Tc-26/32Lx20)
A Board (TC-26/32LX20) The A board for the TC-22LR30 Combo unit is very similar to that of the TC-26/32LX20 model. The H board has been merged onto this model’s A Board. A Board TC26/32LX20 Figure 11... -
Page 18: Power Supply
Power Supply Power Supply (TC-22LR30) The power source for all models is comprised of a Primary and Secondary power supply. The P Board is responsible for generating the primary source voltage used to supply power to the secondary power supply, located on the AP board. It also supplies the voltage that feeds the backlighting circuitry, which is incorporated on the LCD panel. -
Page 19: P Board - Primary Power
P Board - Primary Power The Primary power supply is responsible for generating the following: 1. The standby power supply 2. The primary source voltage (14volts) for the secondary power supply. 3. Backlighting voltage (15 Volts) for the TC-22LR30 STANDBY POWER Circuit The incoming AC voltage passes through the inrush current resistor R7001 and enters the rectifier circuit consisting of D7015, D7022, D7023, and D7024 for conversion to DC. -
Page 20: Ap Board - Secondary Power
AP Board - Secondary Power The Secondary power supply is responsible for producing the various voltages that are required to power the DG board, the A board, the DVD unit and the LCD Panel VCC. These voltages appear on connectors PAP2, PAP5 and PAP6. •... -
Page 21: Tuner / Fip Power Supply (Ap Board)
Tuner / FIP Power Supply (AP Board) The circuit below, located on the AP board, is the power source for the NTSC tuner and the FIP. At power up, the 14Vdc created on the P board is applied to the collector of Q808 via pin 4 of the transformer T802. -
Page 22: Over Current Protection Shutdown Circuits
Over Current Protection Shutdown Circuits There are several protection (shutdown) circuits that monitor the voltage sources for over voltage and over current conditions. They prevent the occurrence of catastrophic failures by shutting down the unit. The circuit below is used to prevent catastrophic failures if the Sub_5V, Sub_9V, Main_9V, or DR_12V becomes shorted. -
Page 23: 14-Volt Power Down Detect Circuit
14-Volt Power Down Detect Circuit he Zero X Detect circuit monitors the presence of the 14 volts source of the main power supply (P board) and the Sub_5V of the AP board. Under normal operation, 5 of the connector DG2 supplies a High to pin 61 of the MPU, IC1106. If, for any reason the Sub_5V or 14 Volts lines drop or disappear, pin 5 of the connector DG2 becomes low level to trigger a complete shut down of the unit Figure 16... -
Page 24: Over Voltage Protection _ Ac Shutdown Latch Circuit
Over Voltage Protection _ AC Shutdown Latch Circuit This protection circuit is responsible for forcing the AC _On voltage to a low if any of these protected voltages mentioned in the next paragraph become excessive. The AC _On voltage is used to activate the relay RL7001, which is used to power up the unit. AC Shutdown Latch Circuit Figure 17 ransistor Q822 monitors the Sub_+3.3V, Sub_9V, Main_11.2V, DVD_5.9V, and... -
Page 25: Power Supply (Tc-26/32Lx20)
Power Supply (TC-26/32LX20) The power source for all models is comprised of a Primary and Secondary power supply. The P Board is responsible for generating the primary source voltage used to supply power to the secondary power supply, located on the AP board. It also supplies the voltage that feeds the backlighting circuitry, which is incorporated on the LCD panel. -
Page 26: Standby Power Supply
Standby Power Supply The standby power supply provides the necessary DC voltage to the system control Microprocessor, the Reset circuit and the EEPROM. A.C. voltage is supplied to the Full Wave rectifier (D7025, D7026, D7031, D7030), through the Line Filter and Transformer T7004. -
Page 27: Power Supply Operation (Tc-32Lh, Tc-26/32Lx20)
Power Supply Operation (TC-32LH, TC-26/32LX20) D7011 T7004 Figure 19 Power On Operation of the DC-to- DC converter The P board contains the drive voltage oscillator circuit that develops the 121 volts needed to drive the LCD backlight. Operation begins with the discharge of transformer T7002. -
Page 28: Power Off Operation Of The Dc-To-Dc Converter
enters pin 6 of IC7001 to begin the oscillation. The pulses that ar e output at pin 1 of the oscillator enter the transformer T7004, causing it to build a magnetic field. The output of the transformer is rectified into 121Vdc and rovided to the LCD panel via the connector P4. - Page 29 This is a simplified overview of the activity that occurs within the primary power supply section when the unit is turned on. Figure 20 Figure 21...
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Page 30: Ap Board - Secondary Power Supply
P Board - Secondary Power Supply The 14 volts derived from the primary power source on the P board enters the AP power board, on the designated connector. The various voltages derived are used to power the DG board, the Audio Control circuitry and the Tuner. If the 24volts shuts down, a 120volt stop signal is generated which causes the unit to shutdown. -
Page 31: Secondary Voltages
Secondary Voltages The Main 3.3V, 2.5V and Sub 5V, are used to provide power to the DG board. IC80 provides a regulated 9 volts to IC808, which serves as the voltage source for the tune Its output is 30 volts. The Main 9,10 and 12.4 volts supply the secondary source vol tage to the rest of the unit. -
Page 32: Video Circuit Explanation
Video Circuit Explanation A Board he A board serves as the entry point for all video signals that will be selectively processed by the DG board via Video Switch IC3101. The main microcontroller, which resides on the DG Board, is responsible for the selection of the designated video input through the use of the I Bus select lines. -
Page 33: Dg Board
DG Board The DG Board is responsible for processing all incoming video signals from the A board. The Vid eo input signals are processed and converted into the LCD format quired to dri ve the LCD Panel. This is accomplished by the main global core IC GC3FM (IC4011) and Video Signaling Processing IC4002. -
Page 34: Video Signal Processing
Video Signal Processing All NTSC video signals are converted to digital data by the analog to digital (A/D) converter circuit located inside the Global Core IC, IC4011. The comb filter in IC40 converts the composite video signal of the main picture to Y and C separated vide data. -
Page 35: Low Voltage Differential Signaling
Low Voltage Differential Signaling The method used to transfer the video information from the Main circuit board to th LCD drive circuit is called Low Voltage Differential Signaling (LVDS). LVDS devices typically consume less power than other signaling systems such as TTL. LVDS devic use a constant current driver. - Page 36 Figure 28...
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Page 37: Hdmi Signal Path
HDMI jack to the DV HDMI connector. Also, connect the Audio Out signal from the external device (set top box or DVD player) to the Audio In jacks. An HDMI to DVI conversion cable (TY-SCH03DH) is available at the Panasonic parts department. -
Page 38: Self-Check Function For Tv Section
Self-Check Function for TV Section The self-check feature is designed to check if a particular component is functioning and it does not actually diagnose the problem .For example “Tuner Check OK” doesn’t’ necessarily mean that it is OK. It pings or selectively addresses that particular device via the I Bus to determine if it exists. -
Page 39: Servicing The Tv Portion
Servicing the TV Portion Service Adjustment Mode for TV Purpose of Adjustment mode Adjustment mode provides the technician with the ability to perform standard video an audio adjustments. ow to enter the Adjustment mode While the unit is powered on, hold down the “Volume Down”... -
Page 40: How To Exit Adjustment Mode
How to exit Adjustment mode Switch off the “Power” button on the main unit or press the “Power” button on the remote control. Warning: If you are making adjustments in the service mode, keep a record of the data value before making the adjustment Service Adjustment Mode Chart Main Item Sub Item... -
Page 41: Servicing The Dvd
Servicing the DVD Service Tools his is a list of the service equipment that will be required for the repair of the DVD portion of the LCD TV Combo DVD Test Disc DVDT-S01 and DVDT-S15 (Supplied from SPC.) Extension Ca ble REKZ0214 (Supplied from SPC) Shakanabi Software: Not supplied as service parts. -
Page 42: Troubleshooting
Troubleshooting This section is in tended to serve as an aid in the fault isolation, troubleshooting, and repair of the LCD TV combo or LH34 chassis type in general. These include the TC- 22LR30 and TC-26/32LX20 models. These are some of the screen display symptoms and conditions that may arise as a res ult of an error or a problem that may occur either uring operation or while entering Self Check mode. -
Page 43: Shutdown Problems
Shutdown Problems If a problem occurs in either the unit or power supply a protection circuit is activated and the unit shuts down. The Power indicator on the front of the unit will flash red severa times indicating an error code. Error codes vary for different models and will be included in t his document. -
Page 44: Led Flashes Once Every 5 Seconds
LED Flashes Once every 5 seconds Check the Backlight supply vol ge from the P board. TC22LR30 -15 volts P2 pin 9-15 Ground pins 1-7. TC26/32LX20- 120 volts P4 pins 1-2. Ground Pins 4-7 LED Flashes Five Times Check the Main 9Volts Regulator Q801 on the AP Board LED Flashes Eight Times Check the Sub 5 Volts regulator, IC808. - Page 45 The Unit Does Not Play Video from Disc Check to see if there is an Input There is problem in signal on the TV Screen. TV circuit. Check the power supply to the Perform a Secondary DVD RAM Drive. Pin1 should be Power supply Check.
- Page 46 Continued from last page A board is defective. Chec he video switch IC3101 the surrounding circuits. Is there an output signal to the Speaker terminals? Check the power supply to the DVD RAM Drive. Pin1 5V There is problem in Pin 4 12V on connector PAP7 TV circuit.
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Page 47: Does Not Record Video To Disc
Does Not Record Video to Disc Is video displayed on TV There is problem in screen? TV circuit. Check the power supply to DVDRAM Check the Primary Power Drive (Pin 1 (5V) and Pin 4 (12V) of ply circuit connector PAP7 on AP Board.) Check for Chroma pin50, Video pin 51 and Luminance pin52 of Replace IC3101. -
Page 48: Does Not Record Audio To Disc
Does Not Recor Audio to Disc There is problem in Is there an output signal to the Speaker terminals? TV circuit. Check the power supply to DVD Perform a RAM Drive on the AP board. Primary Power Supply Check Connector PAP7 Pin1 should have 5V and Pin 4 should have12V Check the Audio Switch IC3102... -
Page 49: Primary Power Supply Check
Primary Power Supply Check Is th e standby Voltage at Check the Fuse F7001, TP7015 7volts? F7002 and IC7005. Check the AC_ON signal Check the Power on switch on at TP7003 (0.7V). the K Board and the connection between PK1 and PAP1. Confirm the PROTECT circuit on AP Board is working. -
Page 50: Secondary Power Supply Check
Secondary Power Supply Check Confirm that the P board is good. Check the R858, 860, 870, 871, 872, 859, Confirm the voltage at R870 and R873. (3V) 861,873, 874, 899, D841 and D842. 1) Confirm the power control signals from IC1106. Check the IC1106 on MAIN_ON: (H) 2.4V, (L) 0V: Pin 39 of PAP2 Circuit Board DG and... -
Page 51: Appendix
Appendix klighting Backlighting Brightne ss fo r Panasonic’s line of LCD TVs is accomplished through the use of Cold Cathode Fluorescent tubes (CCFT), which is currently the light source of choice, by a number of leading manufacturers. Inverter Power Supply... -
Page 52: High Voltage Power Supply
High Voltage P ower Supply A CCF tube needs high voltage. The starting voltage is generally over 1,000 volts and e operating voltage is generally be tween 200 and 500 volts rms. Most CCFT DC to AC inverters are tuned switchers designed to produce a specific voltage, frequency and output current when a designated tube is connected to the output. -
Page 53: Test And Measurement
Test and Measurement This is a basic test setup for measuring the output voltages of the inverter circuit. The output voltage to th e tube can be measured with a dual-channel oscilloscope and two w-capacitance (< 2.5 pf) scope probes. The oscilloscope should be connected differentially, with the probe grounds connected and floating as depicted in the diagram Figure 7 indicates how an oscilloscope can be used for achieving these measurement Figure 34... -
Page 54: Specifications
Specifications Combo Overall Specification Screen Size 22,26,32 inch Picture Brightness 450 cd/m2 Response speed 16 M sec. Pixel W-XGA (1280 x 720) LCD AI (Adaptive New LCD AI Brightness Intensifier) Other 3D Y/C separation DVD-RAM, DVD-R, DVD- Disc Type Discs Played Video, CD-Audio, Video CD, DVD-AUDIO, CD-R/CD-RW Recordable Discs... -
Page 55: Tv Portion
V Portion Table 6... -
Page 56: Dvd Portion
DVD Portion The LCD Combo unit uses a DVD recorde r, very similar to the DMR-E65 Table 7...