SONY KDL-46S2000 Troubleshooting and power supply working.
SONY KDL-46S2000
PCB and Module Descriptions
LCD Panel Assembly LCD Panel Assembly
Included as part of the LCD Panel Assembly is the Logic Board, Backlight Lamps, and the LCD Panel. The Logic Board performs pixel addressing, charging, and discharging functions.
Backlight Inverter Board (Lamp Power Supply)
CCFT’s require a high voltage to start the current flowing from cathode to anode. Typically 1000+ VAC This voltage causes the mercury to ionize, releasing electrons from the molecules. Once ionized, the voltage drops to a nominal level, approximately 400-450 VAC. The Backlight Inverter board takes the DC 17V from the Main Power Supply and converts (or inverts) the DC voltage into and AC voltage. The initial AC voltage output is ~ 1000V lamp ignition voltage and then the output is regulated down to ~ 400VAC for normal lamp operation.
G1-Board (26” & 32”) & G2-Board (40” & 46”) Power Supply)
Except some regulator circuits on the BU-Board, the G1-Board or G2- Board is the power supply system board, which includes the following components and circuits.
# AC Inlet Module
# Main Fuse (F6101)
# Standby 3.3V Power Supply
# 3.3V
# Main Power Supply
# 18.5V
# 10.5V
LCD Panel Assembly LCD Panel Assembly
Included as part of the LCD Panel Assembly is the Logic Board, Backlight Lamps, and the LCD Panel. The Logic Board performs pixel addressing, charging, and discharging functions.
Backlight Inverter Board (Lamp Power Supply)
CCFT’s require a high voltage to start the current flowing from cathode to anode. Typically 1000+ VAC This voltage causes the mercury to ionize, releasing electrons from the molecules. Once ionized, the voltage drops to a nominal level, approximately 400-450 VAC. The Backlight Inverter board takes the DC 17V from the Main Power Supply and converts (or inverts) the DC voltage into and AC voltage. The initial AC voltage output is ~ 1000V lamp ignition voltage and then the output is regulated down to ~ 400VAC for normal lamp operation.
G1-Board (26” & 32”) & G2-Board (40” & 46”) Power Supply)
Except some regulator circuits on the BU-Board, the G1-Board or G2- Board is the power supply system board, which includes the following components and circuits.
# AC Inlet Module
# Main Fuse (F6101)
# Standby 3.3V Power Supply
# 3.3V
# Main Power Supply
# 18.5V
# 10.5V
# 15V
# Power Factor Circuit (PFC)
# Inrush Current Relay
AU-Board (Audio/Video Switching, System Control, & Audio Processing)
The A3U-Board performs all the analog video and audio switching functions. The following video and audio inputs are switched on this board.
Video Input Switching:
# Video Inputs 1, 2, 3 (Composite & S-Video)
# Video Input 4, 5 (Component) Note: The component is not
switched, but does pass through the AU-Board to the BU-Board)
# NTSC Analog Video Signal
Audio Input Switching:
All audio inputs are switched on the AU-Board.
# Audio Inputs 1, 2, 3 (Composite)
# Audio Inputs 4, 5 (Component)
# NTSC Analog Audio Signal
Audio Input Direct to DSP:
# Audio Input 6 (HDMI/DVI)
# Audio Input 7 (PC-IN)
Audio Outputs:
# Optical Digital Audio Output
# Variable/Fixed Audio Output
Audio Processing:
The following circuits are also located on the AU-Board.
# Audio DSP
# Digital Audio Amplifier
# Power Factor Circuit (PFC)
# Inrush Current Relay
AU-Board (Audio/Video Switching, System Control, & Audio Processing)
The A3U-Board performs all the analog video and audio switching functions. The following video and audio inputs are switched on this board.
Video Input Switching:
# Video Inputs 1, 2, 3 (Composite & S-Video)
# Video Input 4, 5 (Component) Note: The component is not
switched, but does pass through the AU-Board to the BU-Board)
# NTSC Analog Video Signal
Audio Input Switching:
All audio inputs are switched on the AU-Board.
# Audio Inputs 1, 2, 3 (Composite)
# Audio Inputs 4, 5 (Component)
# NTSC Analog Audio Signal
Audio Input Direct to DSP:
# Audio Input 6 (HDMI/DVI)
# Audio Input 7 (PC-IN)
Audio Outputs:
# Optical Digital Audio Output
# Variable/Fixed Audio Output
Audio Processing:
The following circuits are also located on the AU-Board.
# Audio DSP
# Digital Audio Amplifier
# Headphone Audio Amplifier
# Variable/Fixed Audio Amplifier
BU-Board (Video Processing)
The circuits located on the BU-Board perform all video processing functions (It is the WEGA engine). The following inputs and circuits are included on the BU-Board.
Video Inputs Directly to TRIDENT:
# Video Input 6 (HDMI/DVI)
# Video Input 7 (PC-IN)
# Video Input 4, 5 (Component)
# ATSC Digital Video Signal
TRIDENT Video Processor IC
The following circuits are included in the TRIDENT IC
# Composite/Component Processor (CCP)
# Digital Reality Creator (DRC)
# Scan Converter
Microprocessor:
# Main Microprocessor
Voltage Regulators
# A9V Regulator
# 1.8V Regulator
# 3.3V Regulator
# 10.5V & Panel 5V Switching Regulator
# 5V Regulator
QS-Board
The QS-Board contains all the ATSC signal decoding and processing circuits. The RF Tuner on the QT-Board supplies the IF-Signal to the QS
# Variable/Fixed Audio Amplifier
BU-Board (Video Processing)
The circuits located on the BU-Board perform all video processing functions (It is the WEGA engine). The following inputs and circuits are included on the BU-Board.
Video Inputs Directly to TRIDENT:
# Video Input 6 (HDMI/DVI)
# Video Input 7 (PC-IN)
# Video Input 4, 5 (Component)
# ATSC Digital Video Signal
TRIDENT Video Processor IC
The following circuits are included in the TRIDENT IC
# Composite/Component Processor (CCP)
# Digital Reality Creator (DRC)
# Scan Converter
Microprocessor:
# Main Microprocessor
Voltage Regulators
# A9V Regulator
# 1.8V Regulator
# 3.3V Regulator
# 10.5V & Panel 5V Switching Regulator
# 5V Regulator
QS-Board
The QS-Board contains all the ATSC signal decoding and processing circuits. The RF Tuner on the QT-Board supplies the IF-Signal to the QS
Board. The IF-signal is further demodulated and decoded to produce the
digital component output from the QS-Board.
QT-Board
The QT-Board contains the RF Tuner and NTSC signal processing circuits. The QT-Board demodulates the terrestrial RF signal, and supplies an IFSignal to the QS-Board (ATSC) and a Composite video signal (NTSC) to the AU-Board video switching circuits.
H1-Board
# Power Button
# Channel Up/Down Button
# Volume Up/Down Button
# TV/Video Button
# Menu Button
H2-Board
# Front Video 2 Input (S-Video, Composite, Audio LR)
# Headphone Jack
H3-Board
# Front Panel LED’s (Power, Standby, and Picture OFF/Timer)
# IR Sensor
# Illumination Sensor
digital component output from the QS-Board.
QT-Board
The QT-Board contains the RF Tuner and NTSC signal processing circuits. The QT-Board demodulates the terrestrial RF signal, and supplies an IFSignal to the QS-Board (ATSC) and a Composite video signal (NTSC) to the AU-Board video switching circuits.
H1-Board
# Power Button
# Channel Up/Down Button
# Volume Up/Down Button
# TV/Video Button
# Menu Button
H2-Board
# Front Video 2 Input (S-Video, Composite, Audio LR)
# Headphone Jack
H3-Board
# Front Panel LED’s (Power, Standby, and Picture OFF/Timer)
# IR Sensor
# Illumination Sensor
Power Supply Block Diagram
Overall System Description
DC Power Supply System
The power supply system for the WAX2 chassis televisions consists of the Standby (STBY) 3.3V Power Supply, Main Power Supply, and the Power Factor Control (PFC) circuit. Aside from various regulator circuits, all power supply circuits are contained on the G1/G2-Board. The G1- Board is used in the 26”, 32”, and 40” models, while the G2-Board is used in the 46” model. The only differences between the two power supply boards are an extra connector, which supplies extra 18V lines to the Panel Assembly, and different component and connector reference numbers. The basic operational functions and troubleshooting procedures discuss in this section can be applied to both the G1-Board and G2-Board. Both the Standby 3.3V and Main Power Supplies are switch-mode power supplies. The configuration and operation is similar to previous models. This section will discuss effective and efficient methods to troubleshoot these circuits.
The AC (110V) is supplied through the AC Inlet Module, which contains the AC line filter. The AC voltage passes through the main fuse F6101 and is applied directly to the Main Power Supply and Standby 3.3V Supply through the InRush Relay & Resistor (R6102) and relay (RY6004) and the Standby 3.3V converter (IC6300). The AC power initially passes through R6102 to limit the initial current surge, which occurs when the TV is first turned on. The AC power is also applied directly to the Standby 3.3V Power Supply. Consequently, as long as the TV is plugged into the AC outlet the Standby 3.3V circuit is activated and supplying STBY 3.3V to Main Microprocessor (BU-Board), IR Sensor (H3-Board). The Standby 3.3V places the TV Microprocessor and IR Sensor in standby mode waiting for an ON command from the remote control or the ON/OFF main unit button on top of the TV. The Standby Power Supply also applies a rectified and filtered 19V through the switch circuit to the PFC circuit when the TV is powered on. The 19V supply ensures that the PFC circuit will condition the AC input immediately upon power ON. The PFC circuit’s purpose is to make the power supply circuits look like a purely resistive load to the external AC power network (current and voltage are in-phase). In reality the internal switch-mode power supply circuit is a highly inductive load (current and voltage are 90 degrees out-of-phase, which causes distortions and inefficiencies in the AC power network when connected directly (no PFC circuit in place). Therefore, the PFC circuit enables the TV to use the AC power more effectively and efficiently.
The Main Power Supply circuit IC6501 develops and supplies all other operating voltages (18.5V, 10.5V, 15V) throughout the television. The Main Power Supply activates once an “ON” command is received and the Inrush Relay is activated. The microprocessor on the BU-board supplies the “Relay-ON” and “Power-ON” signals (CN7009/pin 4 & 6) respectively. The InRush Relay coil is activated by the high “RelayON” signal, and the relay switch closes. The relay switch bypasses the InRush Resistor R6102, the resistor is basically removed from the AC input circuit. The AC power is then applied directly to the Main Power Supply.
To complete the Main Power Supply turn-on sequence the “Power-ON” signal goes high to activate the switch circuit through PH6103, which will then apply 19V from the Standby 3.3V Power Supply IC6104 to the Main Power Supply IC6501 VCC. The 19V is also used to power up the PFC circuit.
Once the Main Power supply is up and running all the secondary voltages (18.5V, 10.5V, 15V) are developed. There are seven regulators on the BU-Board:
# IC1010 9V Regulator
# IC7002 1.8V Regulator
# IC7001 3.3V Regulator
# IC7000 10.5V Regulator
# IC7000 Panel 5V Regulator
# IC7005 5V Regulator
# IC1006 1.8V Regulator
DC Power Supply System
The power supply system for the WAX2 chassis televisions consists of the Standby (STBY) 3.3V Power Supply, Main Power Supply, and the Power Factor Control (PFC) circuit. Aside from various regulator circuits, all power supply circuits are contained on the G1/G2-Board. The G1- Board is used in the 26”, 32”, and 40” models, while the G2-Board is used in the 46” model. The only differences between the two power supply boards are an extra connector, which supplies extra 18V lines to the Panel Assembly, and different component and connector reference numbers. The basic operational functions and troubleshooting procedures discuss in this section can be applied to both the G1-Board and G2-Board. Both the Standby 3.3V and Main Power Supplies are switch-mode power supplies. The configuration and operation is similar to previous models. This section will discuss effective and efficient methods to troubleshoot these circuits.
The AC (110V) is supplied through the AC Inlet Module, which contains the AC line filter. The AC voltage passes through the main fuse F6101 and is applied directly to the Main Power Supply and Standby 3.3V Supply through the InRush Relay & Resistor (R6102) and relay (RY6004) and the Standby 3.3V converter (IC6300). The AC power initially passes through R6102 to limit the initial current surge, which occurs when the TV is first turned on. The AC power is also applied directly to the Standby 3.3V Power Supply. Consequently, as long as the TV is plugged into the AC outlet the Standby 3.3V circuit is activated and supplying STBY 3.3V to Main Microprocessor (BU-Board), IR Sensor (H3-Board). The Standby 3.3V places the TV Microprocessor and IR Sensor in standby mode waiting for an ON command from the remote control or the ON/OFF main unit button on top of the TV. The Standby Power Supply also applies a rectified and filtered 19V through the switch circuit to the PFC circuit when the TV is powered on. The 19V supply ensures that the PFC circuit will condition the AC input immediately upon power ON. The PFC circuit’s purpose is to make the power supply circuits look like a purely resistive load to the external AC power network (current and voltage are in-phase). In reality the internal switch-mode power supply circuit is a highly inductive load (current and voltage are 90 degrees out-of-phase, which causes distortions and inefficiencies in the AC power network when connected directly (no PFC circuit in place). Therefore, the PFC circuit enables the TV to use the AC power more effectively and efficiently.
The Main Power Supply circuit IC6501 develops and supplies all other operating voltages (18.5V, 10.5V, 15V) throughout the television. The Main Power Supply activates once an “ON” command is received and the Inrush Relay is activated. The microprocessor on the BU-board supplies the “Relay-ON” and “Power-ON” signals (CN7009/pin 4 & 6) respectively. The InRush Relay coil is activated by the high “RelayON” signal, and the relay switch closes. The relay switch bypasses the InRush Resistor R6102, the resistor is basically removed from the AC input circuit. The AC power is then applied directly to the Main Power Supply.
To complete the Main Power Supply turn-on sequence the “Power-ON” signal goes high to activate the switch circuit through PH6103, which will then apply 19V from the Standby 3.3V Power Supply IC6104 to the Main Power Supply IC6501 VCC. The 19V is also used to power up the PFC circuit.
Once the Main Power supply is up and running all the secondary voltages (18.5V, 10.5V, 15V) are developed. There are seven regulators on the BU-Board:
# IC1010 9V Regulator
# IC7002 1.8V Regulator
# IC7001 3.3V Regulator
# IC7000 10.5V Regulator
# IC7000 Panel 5V Regulator
# IC7005 5V Regulator
# IC1006 1.8V Regulator
IC7000
develops the Panel 5V, which is supplied to the Logic Board (part of
the LCD Panel Assembly). IC7000 is dual package switching regulator,
which also develops the 10.5V used to develop the D5V (IC7005) and to
power the QS-Board, which in turn develops voltages to power the
QT-Board. The D5V remains on the BU-Board, and is also sent to the
AU-Board to power various digital circuit.
IC1010 develops the A9V. The A9V powers the A/V Switcher IC2001, Audio DSP IC7001, Digital Amplifier, and several of audio amplifiers on the AU-board. IC7002 and IC1006 both develop the 1.8V, which powers various circuits on the BU-board. IC7001 develops the 3.3V, which powers the Optical Audio Output LED on J9003. Notice that IC7002, IC7001, and IC7000 all have “Power” control signals (Power 2, Power 3, and Power 4) supplied from the Main Microprocessor on the BU-Board. In most cases if one of these signals is missing a protection mode activates, and the TV shuts down. Therefore, these signals will be used as test points in particular Protection Mode troubleshooting procedures
Backlight Inverter Board (Lamps Power Supply)
CCFT’s require a high voltage to start the current flowing from cathode to anode. Typically 1000+ VAC This voltage causes the mercury to ionize, releasing electrons from the molecules. Once ionized, the voltage drops to a nominal level, approximately 400-450 VAC. The Backlight Inverter board takes the DC 17V from the Main Power Supply and converts (or inverts) the DC voltage into and AC voltage. The initial AC voltage output is ~ 1000V lamp ignition voltage and then the output is regulated down to ~ 400VAC for normal lamp operation.
IC1010 develops the A9V. The A9V powers the A/V Switcher IC2001, Audio DSP IC7001, Digital Amplifier, and several of audio amplifiers on the AU-board. IC7002 and IC1006 both develop the 1.8V, which powers various circuits on the BU-board. IC7001 develops the 3.3V, which powers the Optical Audio Output LED on J9003. Notice that IC7002, IC7001, and IC7000 all have “Power” control signals (Power 2, Power 3, and Power 4) supplied from the Main Microprocessor on the BU-Board. In most cases if one of these signals is missing a protection mode activates, and the TV shuts down. Therefore, these signals will be used as test points in particular Protection Mode troubleshooting procedures
Backlight Inverter Board (Lamps Power Supply)
CCFT’s require a high voltage to start the current flowing from cathode to anode. Typically 1000+ VAC This voltage causes the mercury to ionize, releasing electrons from the molecules. Once ionized, the voltage drops to a nominal level, approximately 400-450 VAC. The Backlight Inverter board takes the DC 17V from the Main Power Supply and converts (or inverts) the DC voltage into and AC voltage. The initial AC voltage output is ~ 1000V lamp ignition voltage and then the output is regulated down to ~ 400VAC for normal lamp operation.
Power-ON Sequence
The AC power cord is plugged into the AC outlet and is applied to the G1/G2-Board.
The AC voltage supplied to the G1/G2-Board is applied directly to the InRush-Relay and the Standby 3.3V power supply circuit. The Standby 3.3V is applied to the Main Micro and places it into standby mode . It also turns ON the IR sensor.
The Main-Microprocessor located on the BU-Board receives a ON command when either the ON /OFF button is pressed on the remote or the TV top panel .
The Green Power-LED on the TV front panel illuminates immediately after an ON command is received and processed.
The Green Power-LED remains illuminated.
The Main Microprocessor sends the following signals
Power-1: Main Power Supply IC6501 (Power-ON)
Power-2: IC7001 (3.3V Reg) & IC7002 (1.8V Reg) ON
Power-3: IC7000 (10.5V Output) ON
Power-4: IC7000 (Panel 5V Output) ON
The Main Power Supply IC6501 turns ON and all the television operating voltages are developed.
The “Relay-ON signal turns ON the InRush Relay, which bypasses the InRush resistor.
All microprocessor I2C communications commence.
After all the power supply voltages and microprocessor communications have been successfully develop the Green Power LED will glow steady.
The AC voltage supplied to the G1/G2-Board is applied directly to the InRush-Relay and the Standby 3.3V power supply circuit. The Standby 3.3V is applied to the Main Micro and places it into standby mode . It also turns ON the IR sensor.
The Main-Microprocessor located on the BU-Board receives a ON command when either the ON /OFF button is pressed on the remote or the TV top panel .
The Green Power-LED on the TV front panel illuminates immediately after an ON command is received and processed.
The Green Power-LED remains illuminated.
The Main Microprocessor sends the following signals
Power-1: Main Power Supply IC6501 (Power-ON)
Power-2: IC7001 (3.3V Reg) & IC7002 (1.8V Reg) ON
Power-3: IC7000 (10.5V Output) ON
Power-4: IC7000 (Panel 5V Output) ON
The Main Power Supply IC6501 turns ON and all the television operating voltages are developed.
The “Relay-ON signal turns ON the InRush Relay, which bypasses the InRush resistor.
All microprocessor I2C communications commence.
After all the power supply voltages and microprocessor communications have been successfully develop the Green Power LED will glow steady.
The Power-ON sequence is completed.
Main & Standby Power Supply
When troubleshooting a “Unit will not turn ON” problem in previous models the Red Standby LED was very helpful. It indicated that at least the Standby Power Supply was functioning when lit. Unfortunately, there is no Red Standby LED on any of the WAX2 chassis models. Consequently, the only visual check to determine if the Standby 3.3V Power Supply is functioning is to press the ON/OFF Power button and watch for the Power LED on the front panel to illuminate Green. If the Power LED illuminates Green when the Standby 3.3V power supply and the Main Microprocessor (this processor controls the LEDs) are functioning. A steady glowing Green Power LED indicates successful Power-ON sequence and Microprocessor communications.
If the Power LED glows steady with no video or audio present check the 10.5V at CN6202 or CN6200/pin 7 on the G1/G2-Board and D5V at CN7008/pin 3 on the BU-Board. A loss of either of these voltages will cause this condition. Furthermore, checking these voltages will determine if the failure exists on the G1/G2-Board or BU-Board. The 10.5V is produced by the Main Power Supply IC6501 on the G1/G2- Board and the D5V is produced by the 5V regulator on the BU-Board. Therefore, if the 10.5V is missing a CN6202 or CN6200 then the failure exists on the G1/G2-Board — replace the G1/G2-Board. However, if the D5V is missing at CN7008 then the failure exists on the BU-Boad — replace BU-Board.
NOTE:A loss of D5V due to a power supply failure will trigger the protection mode circuits. Therefore, you only need to confirm proper connection of the D5V wiring harness (or damaged wiring). If the voltages & connections are OK and the Power LED is steady Green but there is still no video and audio, you should redirect your troubleshooting efforts to the video and/or audio sections.
If
the Power LED begins flashing Red then the Main Microprocessor has
detected a system failure and has placed the TV in a particular
Protection Mode. The Red LED flash pattern (number of flashes – LED ON,
should between LED pauses – LED OFF) should be noted. The pattern
indicates the particular failure that has occurred. For example, a Red
LED flashing 5 times between pauses (5X) indicates a general power
supply failure. Let us go back and analysis the situation where the
Power LED does not light Green after the TV receives an “ON” command.
The first step in troubleshooting a “No Green Power LED” condition is to
confirm that the TV is securely plugged into an active AC (110VAC)
outlet.When troubleshooting a “Unit will not turn ON” problem in previous models the Red Standby LED was very helpful. It indicated that at least the Standby Power Supply was functioning when lit. Unfortunately, there is no Red Standby LED on any of the WAX2 chassis models. Consequently, the only visual check to determine if the Standby 3.3V Power Supply is functioning is to press the ON/OFF Power button and watch for the Power LED on the front panel to illuminate Green. If the Power LED illuminates Green when the Standby 3.3V power supply and the Main Microprocessor (this processor controls the LEDs) are functioning. A steady glowing Green Power LED indicates successful Power-ON sequence and Microprocessor communications.
If the Power LED glows steady with no video or audio present check the 10.5V at CN6202 or CN6200/pin 7 on the G1/G2-Board and D5V at CN7008/pin 3 on the BU-Board. A loss of either of these voltages will cause this condition. Furthermore, checking these voltages will determine if the failure exists on the G1/G2-Board or BU-Board. The 10.5V is produced by the Main Power Supply IC6501 on the G1/G2- Board and the D5V is produced by the 5V regulator on the BU-Board. Therefore, if the 10.5V is missing a CN6202 or CN6200 then the failure exists on the G1/G2-Board — replace the G1/G2-Board. However, if the D5V is missing at CN7008 then the failure exists on the BU-Boad — replace BU-Board.
NOTE:A loss of D5V due to a power supply failure will trigger the protection mode circuits. Therefore, you only need to confirm proper connection of the D5V wiring harness (or damaged wiring). If the voltages & connections are OK and the Power LED is steady Green but there is still no video and audio, you should redirect your troubleshooting efforts to the video and/or audio sections.
NOTE: Plug a typical house lamp into suspect AC outlet to confirm an active 110VAC output. Furthermore, note lamp brightness to determine and active but low AC voltage output. If the AC outlet checks OK, then the next step is to confirm that the AC voltage is applied to the G1/G2-Board. Check for 110VAC at CN6102 on the G1/G2-Board. If 110VAC is not present, check for a damage AC cord or plug. If all connections are OK replace the AC Input Module. If 110VAC is present at CN6102 perform the following checks.
1) Check the Main Fuse (F6101) on the G1/G2-Board
2) Check for Standby 3.3V
You can use an Ohmmeter or AC Voltmeter to check for a defective Main Fuse. The fuse should read 0 ohms or have 110VAC on both side with reference to Hot Ground (white wire on CN6102). Replace fuse if open. If the new fuse opens again replace the G1/G2-Board. If the Main Fuse checks OK, then AC voltage will be applied directly to the Standby Power Supply and 3.3V is developed at the supply output. Check for 3.3V at CN6202 or CN6200/pin 5 on the G1/G2-Board. Missing 3.3V indicates a defective Standby Power Supply – replaced the G1/G2-Board. The presence of 3.3V indicates the Standby Power Supply is functioning. The next step is to confirm the 3.3V is making it to the BU-Board and the Main Microprocessor. Check for the 3.3V at CN1002/pin 10 on the BU Board.
Missing 3.3V indicates a loose or damaged connection between the G1/
G2-board and the BU-Board. Secure or repair connections. The presence of 3.3V indicates a defect on the BU-Board or a defective Main Microprocessor – replace the BU-Board.
Backlight Inverter Board (Lamps Power Supply)
Caution: Do not attempt to directly measure the Backlight Inverter Board output directly. 1000V or greater is present at the outout on initail power ON.
The best way to check the Inverter Board output is to place your VOM probe on top of the individual plastic lamp connectors. Set the VOM to AC volts, place the probe on top of the connector directly above one of the two wires (each connector feeds two lamps). Place the VOM probe over each wire for proper measurements. A good output will measure approximately 3VAC. A bad output will measure aproxiamatey 1VAC or less. If any single output is bad replace the Backlight Inverter Board. If all Inverter Board outputs are bad, check the 18V supply voltage from the Main Power supply before replacing the Backlight Inverter Board. If the 18V is missing check for loose or damaged connections between the G1/G2-Board and the Backlight Inverter Board. If the 18V is present at the Inverter Board, however, all output are bad then replace the Backlight Inverter Board.
