SONY KDL-26,32, 40, 46S2000 Failure Protection System Overall Block.
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KDL-26, 32, 40, 46S2000 Video, Temperature, Audio
Protection Circuits
The failure protection system (aka. Self-diagnostics
routines) for the WAX2 chassis monitors the following circuits for abnormal
conditions. If the TV microprocessor detects a failure it will activate the
front panel Standby-LED, which will flash a unique RED pattern depending on
the failure that occurred. The bullet list below lists all the monitored
circuits and their unique flash pattern.
- 10.5V & Panel 5V Low-Voltage Protection (DCALERT3) 1X Red Power-LED Flash Pattern
- D5V Low-Voltage Protection (DC ALERT 2) 2X Red Power-LED Flash Pattern
- 3.3V & 1.8V Low-Voltage Protection (DC ALERT 1) 3X Red Power-LED Flash Pattern
- Backlight Protection 4X Red Power-LED Flash Pattern
- Overall Power Supply Protection 5X Red Power-LED Flash Pattern
- Audio Output Protection 6X Red Power-LED Flash Pattern
- Internal Temperature Protection 7X Red Power-LED Flash Pattern
- TRIDENT (Scan Converter) Protection 8X Red Power-LED Flash Pattern
Over-Voltage & Panel 5V Low-Voltage Protection (1X Flash
Pattern)
The service manual labels this protection mode as DC_ALERT
3. The 10.5V and Panel 5V supplies are monitored for a low-voltage condition.
The 4.7V zener diode D7500 and transistors Q7500 and Q7502
on the BU-Board monitor the 10.5V. In normal operation D7500 is in the breakdown mode (ON) as long as the 10.5V supply stays
above 4.7V. The zener has a voltage drop of 4.7V leaving 5.8V, which is applied
to the base of Q7500 turning Q7500 ON and Q7502 OFF. With Q7502 OFF 3.1V is
developed at IC1001/pin 154 (Main Microprocessor) through the voltage divider
circuit of R7517 and R7518 using the Panel 5V supply voltage from switching
regulator IC7000.
If the 10.5V supply
drops below 4.7V D7500 will turn OFF, Q7500 will turn OFF and Q7502 will turn
ON, and a ground is applied to IC1001/pin 154 pulling the pin low. Consequently, the Main Microprocessor
detects a 10.5V failure and the Red Standby-LED fl ashes a 1Xpattern and the TV
shuts down.
D5V Low-Voltage Protection (2X Flash Pattern)
The service manual labels this protection mode as DC_ALERT
2. The D5V supply is monitored indirectly through the voltage divider
consisting of R7515 and R7516 on the BU-Board. IC7005 regulates the
10.5V (from the switching regulator IC7000) down to 5V. The 5V
(or D5V) is then applied to the Main Microprocessor IC1001/pin 153. If the D5V drops so will the 3.1V at the
mid-point of the voltage divider. Consequently, the Main Microprocessor detects
a D5V failure and the RED Standby-LED flashes a 2Xpattern and the TV shuts
down.
3.3V, 2.4V, & 1.8V LVP-Voltage Protection (3X Flash
Pattern)
The service manual labels this protection mode as DC_ALERT
1. This protection mode is activated if any one of the following regulators failures.
IC7001 3.3V Regulator
IC7002 1.8V Regulator
IC7004 2.4V Regulator
A transistor and a diode monitor each regulator output.
IC7001 is monitored by Q7504 and D7508; IC7002 is monitored by Q7506 and D7510; IC7004 is monitored by Q7505 and D7509. The
transistors are ON in normal operation, turned ON by the voltage output of each
regulator. With the transistors ON a ground is applied to the anode of each
diode, therefore, each diode is OFF (or reverse biased). All three diode
outputs go to the base of a single transistor Q7503. The collector of Q7503 is
connected directly to the Main Microprocessor IC1010/pin 163. In normal operation the voltage level at IC1001/pin 163 is
3.1V. If any of the three regulators failure the corresponding transistor
(Q7504, 7505,or Q7506) will turn
OFF, and the ground is removed from the anode of the corresponding diode
(D7508, D7509, or D7510). With the ground removed a high will be applied to the
anode of the diode through the associated pull-up resistor (R7542, R7543,
R7544), and the diode will forward bias, applying a high to the base of Q7503.
The transistor turns ON applying a ground to IC1001/pin 163 pulling the pin
low. Consequently, the Main Microprocessor detects a regulator failure and the
RED Standby-LED fl ashes a 3Xpattern and the TV shuts down.
Backlight Protection (4X Flash Pattern)
This protection mode monitors the operation of the Backlight
Inverter Board and the Lamps. The
Inverter Board is the Lamp power supply, which produces the high alternating
voltage necessary to drive the Cold Cathode Fluorescent Lamps (CCFL) used for
the LCD panel backlighting. There are three main causes for the activation of
this protection mode.
Loss of 18.5V supply to the Inverter Board (at CN6202 on the
G2-Board)
Loss of 3.2V Backlight ON signal
Defective Inverter Board Circuits
Defective Lamp(s)
Loss of 18.5V supply to the Inverter Board (at CN6202 on the
G2-Board)
The 18.5V is the power supply for the Backlight Inverter
board. However, the 18.5V also drives two voltage regulators on the BU-Board
ure 3-1). Therefore, if the 18.5V is lost due to a Main Power Supply failure a
5X flash pattern is generated. The
Main Microprocessor generates a 4X fl ash pattern only if there is a loss of
18.5V at CN6203. In other words, the Main Power Supply is functioning OK (producing 18.5V), however, the 18.5V is not
making it to CN6203. There is a poor connection or open circuit in the
physical connection between
the G1/G2-Board and the Inverter
Board. Consequently, the Backlight Inverter fails to start, the Panel Detect
line goes low (CN7009/pin 3), and the microprocessor detects a failure.
Loss of 3.2V Backlight ON signal.
Confirm 3.2V at CN7009/pin 1 on the BU-Board.
The Main Microprocessor on the BU-Board turns on the Backlight
Inverter using the 3.2V Backlight-ON signal. You can measure this voltage at CN7009/pin 1 on the BU-Board. If the Main Microprocessor
fails to send this signal (rare occurrence) or if there is an open path
(confirm secure & undamaged connectors between the BU-Board and the
Inverter Board) to the Backlight
Inverter board then
the Panel Detect line
goes low (CN8603/pin 4)and the
microprocessor generates a 4X flash pattern.
Defective Inverter Board Circuits or Lamp Failure.
Confirm 18.5V (Power Supply) and 3.2V (Backlight-ON).
In the case of an actual Backlight Inverter board circuit or
Lamp failure, the 18.5V and the 3.2V voltages should be OK. Therefore, prior to
shutdown you can measure these voltages to confirm that power supply and control
signal is present. If these
two voltages check OK, but the Backlight does not light and the Panel Detect
line goes low (CN8603/pin 4) then the defect exists on the Backlight Inverter
board or a Lamp has failed. In either
case, the complete panel assembly must be replaced to fix the problem.
Overall Power Supply Protection (5X Flash Pattern)
The purpose of this protection mode is to monitor and
indicate a failure of the Main Power Supply
(IC6100) on the G1/G2-Board. The
primary voltage monitor is the 18V. If the Main Power Supply does start or
remain running the 18V will not be developed and the Main microprocessor will
detect an overall power supply failure.
The 18V is applied to
the voltage divider consisting of R1031, R1034, and R1037. The voltage across
R1037 (3.1V), which is stabilized and delayed by C1007 is applied to the Main
Microprocessor IC1001/pin82. The
presence of the 3.1V indicates a properly functioning Main Power Supply. If the
18V is not developed for any reason, then the 3.1V is not developed and the
Main Microprocessor detects a power supply failure (5X).
There is a multitude of failures that can cause the Main
Power Supply shutdown. The following list identifies the possible failures.
Failure of the Main Converter IC6100
Loss of 3.3V
Power-ON signal from
Main Microprocessor IC1001/pin
32
Excessive 19V Supply to the PFC Circuit
Failure of InRush Relay
18.5V Over-Voltage
Condition.
Main Power Supply Converter IC6100
Confirm that both the 3.3V Power-ON signal and the 18.5V
increase, and stabilize to their respective levels both protection-mode
shutdown.
The presence of the 3.3V indicates that the converter IC6100
is most likely getting the necessary VCC input, and the presence of the 18.5V
indicates that the converter IC6100 is starting and developing the secondary
voltages, therefore, some other fault is shutting the TV down.
It is rare that
IC6100 will fail. This IC (MCZ3000D) integrated circuit has been very reliable
in many previous chassis’s.
Loss of 3.3V Power-ON signal from Main Microprocessor.
The Power-ON (or Power 1) signal is generate by the Main
Microprocessor IC1001/pin32 on the BU-Board.
The tricky part about troubleshooting this failure is determining if the
Main Microprocessor is failing to generate the Power-On signal or if one of the
two latch circuits (Q6202/Q6204 & Q6105/Q6107) on the G1/G2-Board is
pulling the Power-ON signal low. Notice that there are two latch circuits
located on the G1/G2-Board. These latch circuits connect
directly to the Power-ON signal line.
If the Power-ON signal shows no signs of increasing towards
3.3V then the most likely failure is the Main Microprocessor IC1001. Before
replacing the BU-Board check all connections between the BU-Board and G1/G2-
Board.
If the Power-ON signal increases to 3.3V and then goes to
0V, then one of the latch circuits is being activated.
NOTE: The Power-ON signal can also be check unloaded.
Disconnect CN6202/CN6203 from the G1/G2-Board and check if the 3.3V is present.
If the 3.3V is present, then this indicates that the Latch circuits are
activating due to a failure on the G1/G2-Board and pulling the Power-ON line
low.
One or more of the following events can trigger the latch
circuits.
Excessive 19V Supply to the PFC Circuit
Failure of Inrush Relay
18.5V Over-Voltage Condition
Loss of 18.5V (at CN7009 to the BU-board)
Confirm connections between G1/G2-Board and the BU-Board for
the 18.5V path.
Audio Output Protection (6X Flash Pattern)
The protection circuit
(Q7014, Q7015, Q7016, Q7017, Q7018, and Q7021) mounted on the AU-Board monitors
the audio amplifier outputs (speaker lines) for a shorted condition or for the
presence of any DC voltage level (positive or negative). If either of these
conditions is detected the protection circuit alerts the Main Microprocessor of
the failure and the Standby-LED Flashes a 6Xfl ash pattern.
Internal Temperature Protection (7X Flash Pattern)
The temperature sensor (IC1007) is mounted on the component
side of the BU-Board next to CN1700. IC1007 monitors the internal temperature
of the TV set, and communicates any temperature abnormality to the Main
Microprocessor over the I2C bus.
The following parameters affect internal temperature.
TV Ventilation,
Local External Temperature (Room Temperature)
Internal Component Operating Temperatures
In most cases, one of the following actions will solve a
temperature failure.
Clear the TV areas of ventilation
Relocate the TV set away from any area heating elements
Provide adequate space between TV cabinet and walls (at least 4”)
Replace Temperature Sensor IC1007
If the TV set shuts down immediately after turn-on and the
Red Standby LED indicates a temperature problem (7X fl ash pattern), then the
most Likely failure is the temperature sensor IC1007. The reason for this deduction is that a
actual excessive temperature situation will take time to occur. The internal TV
temperature must increase and IC1007 must detect the excessive temperature, and
then communicate this information to the main Microprocessor. This whole
process takes time. However, if the temperature sensor (IC1007) itself has
failed, the Main Microprocessor will not be able to communicate with IC1007
when the TV is first turned ON and the TV will, in comparison, immediately shut
OFF.
TRIDENT Protection (8X Flash Pattern)
TRIDENT is the name for the integrated circuit (IC5000) that
includes all the video processing circuitry, including the Scan Converter
circuit. This Protection mode monitors the operation of the internal Scan
Converter. A failure of the Scan Converter is communicated over the I2C bus
between the TRIDENT and Main Microprocessor, and a 8X flash pattern will occur.
