TV: LG 47LE5400-UC.AUSWLJR
Symptoms: When i press the power button, i hear the relay click. The front panel touch buttons illuminate and they make a sound when i press on them.
No backlights (even for a brief moment), and the optical audio light is not on. Power supply appears to be fine though (measurements are at the bottom).
The mainboard sends the "power on" signal correct as well as PWM DIM, but DRV_ON is not sent.
I disconnected the cable between the SMPS and main board. I jumped 3.3STBY to POWER_ON as well as 3.3STBY to DRV_ON with two 10K resistors. The backlights came on just fine (yay!). The string tested good as well with the LED tester with the unit off.
I'm suspecting that the main board has an issue. Likely a problem with the main processor BGA.
On a side note, I obtained a 55" version of this TV (LG 55LV5500-UA.AUSYLJR) in 2016 and it failed in the same manner. I ended up replacing the main board for that one.
Anyway, I measured the voltages with the TV in STBY and when it's ON. Looks like i'm missing DRV_ON. What's the chances it's the micom firmware? (i'm assuming remote).
Any thoughts on this would be greatly appreciated. If there are no other suggestions, this thing will get a quick "heatgun treatment" to the BGA under the main heatsink to see if that temporarily fixes it.
Symptoms: When i press the power button, i hear the relay click. The front panel touch buttons illuminate and they make a sound when i press on them.
No backlights (even for a brief moment), and the optical audio light is not on. Power supply appears to be fine though (measurements are at the bottom).
The mainboard sends the "power on" signal correct as well as PWM DIM, but DRV_ON is not sent.
I disconnected the cable between the SMPS and main board. I jumped 3.3STBY to POWER_ON as well as 3.3STBY to DRV_ON with two 10K resistors. The backlights came on just fine (yay!). The string tested good as well with the LED tester with the unit off.
I'm suspecting that the main board has an issue. Likely a problem with the main processor BGA.
On a side note, I obtained a 55" version of this TV (LG 55LV5500-UA.AUSYLJR) in 2016 and it failed in the same manner. I ended up replacing the main board for that one.
Anyway, I measured the voltages with the TV in STBY and when it's ON. Looks like i'm missing DRV_ON. What's the chances it's the micom firmware? (i'm assuming remote).
Any thoughts on this would be greatly appreciated. If there are no other suggestions, this thing will get a quick "heatgun treatment" to the BGA under the main heatsink to see if that temporarily fixes it.
Code:
P201, odd pins are the top row, even pins bottom row. Pin SIG V_OFF V_ON 1 PWR_ON 0 3.329 3 20V 0 21.26 5 GND 0 0 7 GND 0 0 9 3.5V 3.49 3.438 11 3.5V 3.49 3.438 13 GND 0 0 15 GND 0 0 17 12V 0 12.46 19 12V 0 12.46 21 12V 0 12.46 23 SIN 0 0 2 20V 0 21.26 4 20V 0 21.26 6 GND 0 0 8 GND 0 0 10 3.5V 3.49 3.441 12 3.5V 3.49 3.441 14 GND 0 0 16 V-sync 0 0.252 18 DRV ON 0 0.043 20 SCLK 0 0.21 22 PWM DIM 0 2.917 24 ErrOut 0 0
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