This 50 inch LG LED (LCD) TV was given to me not working. Powering it on, the logo flashes once for 1/4 second then black. Front panel red LED blinks 3x (I think... see below) then the LED turns off. TV stays on until I press the Power button again. There is an image on the LCD panel--I press the "Settings" button on the TV and this brings up menus I can see with a flashlight / torch.
(The front panel red error code LED blink sequence is a bit confusing to me. The LED is on when the TV is off. I press the Power button and the LED *very briefly* goes off--maybe 1/10 second--then goes on-off-on-off-on-off and stays off as long as the TV is powered on. I guess this is 3 blinks?)
Voltages at the PS board output connector are all present and correct.
Measuring the backlight output connector on the PS board (with cable to the backlight connected), I back-probe the cable connector, choose MAX setting on the meter, and press the TV Power button. I get a maximum reading as the backlight LEDs flash, then a minimum reading after they turn off:
pins 1-2: 74v max, dropping down to 4v.
pins 3-4: 114v max, dropping down to 4v.
I found 2 electrolytic caps on the PS board that measured ESR out of spec: a small 47uF/100v; and the HV 100uF/450v (which I replaced with a 270uF/450v that I had on hand). Is that 270uF OK in place of the 100uF? Or is it important that I find a direct replacement? The 270uF is a Cornell-Dubilier. The voltage measured across the cap is 395vdc.
So that's the history. Do these symptoms point to simply bad backlight LED strips?
Also, where to get a service manual for this?
Thanks for reading.
(The front panel red error code LED blink sequence is a bit confusing to me. The LED is on when the TV is off. I press the Power button and the LED *very briefly* goes off--maybe 1/10 second--then goes on-off-on-off-on-off and stays off as long as the TV is powered on. I guess this is 3 blinks?)
Voltages at the PS board output connector are all present and correct.
Measuring the backlight output connector on the PS board (with cable to the backlight connected), I back-probe the cable connector, choose MAX setting on the meter, and press the TV Power button. I get a maximum reading as the backlight LEDs flash, then a minimum reading after they turn off:
pins 1-2: 74v max, dropping down to 4v.
pins 3-4: 114v max, dropping down to 4v.
I found 2 electrolytic caps on the PS board that measured ESR out of spec: a small 47uF/100v; and the HV 100uF/450v (which I replaced with a 270uF/450v that I had on hand). Is that 270uF OK in place of the 100uF? Or is it important that I find a direct replacement? The 270uF is a Cornell-Dubilier. The voltage measured across the cap is 395vdc.
So that's the history. Do these symptoms point to simply bad backlight LED strips?
Also, where to get a service manual for this?
Thanks for reading.
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