Section 2 - Troubleshooting Procedures; Power Symptom Troubleshooting; Normal Operation; Failure Symptoms - Sony KDL-55EX500 Troubleshooting Manual

Power Symptom Troubleshooting

Normal Operation

Reference Figure 2-1 and 2-2
110VAC is applied directly to the G5E-Board or G8S-Board. It can be
measured at CN6102 or CN1 respectively. In the standby mode the AC
power passes through the main fuse F6101 or F101. The AC power passes
through R6118 or R106 (Inrush resistors), and D6001 and is applied to
the Main DC/DC Converter IC6301 and the Standby DC/DC Converter
IC6103 on the G5E-Board. IC6301 is not active in the standby mode.
However, IC6103 is active in standby mode and outputs STBY 3.3Vdc
as long as AC power is applied to the TV and the RED Standby LED is
illuminated on the front panel. The Standby 3.3Vdc is supplied to the TV-
Microprocessor, Switch Unit (Power Key), and HRK-Board (IR Sensor) in
the standby mode. The G8S-Board has three separate power supplies for
the 24V, 12V, and Standby 3.3V supplies. However, the basic operation
is the same as the G5E-Board. Only the Standby 3.3V is active in the
Standby mode.
Once a ON command is received form the remote controller or the power
button on the Switch Unit the TV-Microprocessor outputs the Power-ON
signal. The Power-On signal is applied to the G5E-Board or G8S-Board.
On the power supply board the Power-On signal switches the 19V from
the standby power supply to activate the PFC and Main Power supply
IC6301. One relay click is heard at power-on. The relay engages to bypass
the inrush resistors R6118 or R106 during the ON state.
The main power supply IC6301 (Z501, 60") is now active and outputting all
secondary supplies. The 12Vdc secondary is the supply voltage for all the
voltage regulators on the A-Board. The AU12V is the supply voltage for
the audio output amplifier. The 60" model's power supply (Z301) will also
output 24V which is the supply voltage for the backlight inverter boards.
The D1-Board in the 55" model will develop and output the backlight high-
voltage (1KV) to the Balancer board and the CCFL backlights.
CTV-65

Section 2 - Troubleshooting Procedures

Failure Symptoms

Reference Figures 2-1, 2-2, 2-3, and 2-4

No Power/Dead Set (No RED Standby LED)

In a dead set condition there will be No RED Standby LED illumination in
the Standby Mode (TV plugged into an active AC Outlet).
The following bullet list gives the possible failures for a "No Power/Dead
Set" condition.
• Loss of AC Power (Dead AC Wall Outlet)
• Loss of AC-OFF-DET
• Loss of Standby 3.3Vdc
• Loss of REG12V
• Loss of Power-On
• Defective Main Microprocessor
The first step in troubleshooting a "No Power/Dead Set" condition is to
confirm that 110ACV power from an active AC wall outlet is applied to the
G5E-Board or G8S-Board. AC power is applied to, and can be measured
at CN6102 on the G5E-Board and at CN1 on the G8S-Board.
Next, check for the presence of the AC-OFF-DET voltage at CN6201/pin 2
or CN2/pin 2. If the AC-OFF-DET circuit is working properly 3V should be
measured. If the 3V is not present replace the G5E-Board or G8S-Board.
If the 3V is present, then the Standby Power supply, Main power supply,
or Main microprocessor is defective. Further troubleshooting is necessary
to determine the defective component.
After confirming the AC power and AC-OFF-DET, check for a defective
Standby 3.3Vdc power supply. Check for the 3.3V secondary voltage at
CN6201/pin 1 or CN2/pin 1. As long as AC power is applied to the TV
the Standby power supply should be active and outputting 3.3Vdc. If the
3.3V is not present then Standby power supply is defective. Replacing the
power supply board will fix the problem.
If the Standby 3.3V is okay, the next step is to check the REG12V from
12