RCA LED52B45RQ no video, no backlight, status light illuminated red and does not change when power is depressed. Power Supply shows a constant on state (On/Off 4.6V) when plugged in and voltages at the connector appear normal, but PFC voltage is only 165 volts suggesting no boost.
Pin----------Name----------Plugged In Measured
12----------12V-------------12V
11----------12V-------------12V
10----------GND--------------0
09----------GND--------------0
08----------GND--------------0
07----------5V---------------5V
06----------5V---------------5V
05----------5Vsb-------------5V
04----------ON/OFF----------4.6V
03----------5V----------------5V
02----------5V----------------5V
01----------GND--------------0
So it seems strange that the voltages are there, but the PFC is not working?
Checked Power Supply on bench (unloaded) and when On/Off is tied to 5Vsb through 1K resistor 12V and 5V appear on connector, but boost is 165V instead of the expected 395V.
Verified all components in the area of U101 (FAN7930C), verified VCC present on U101 pin 8 and it has 5V referenced to AC ground.
Power MOSFET and Diode check OK
No pulses (a bit of noise) on output pin 7 of U101
Any thoughts - order and replace U1
Thanks
Pin----------Name----------Plugged In Measured
12----------12V-------------12V
11----------12V-------------12V
10----------GND--------------0
09----------GND--------------0
08----------GND--------------0
07----------5V---------------5V
06----------5V---------------5V
05----------5Vsb-------------5V
04----------ON/OFF----------4.6V
03----------5V----------------5V
02----------5V----------------5V
01----------GND--------------0
So it seems strange that the voltages are there, but the PFC is not working?
Checked Power Supply on bench (unloaded) and when On/Off is tied to 5Vsb through 1K resistor 12V and 5V appear on connector, but boost is 165V instead of the expected 395V.
Verified all components in the area of U101 (FAN7930C), verified VCC present on U101 pin 8 and it has 5V referenced to AC ground.
Power MOSFET and Diode check OK
No pulses (a bit of noise) on output pin 7 of U101
Any thoughts - order and replace U1
Thanks
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