Hi everybody!
I have a 55" LED TV made by Vestel. All of a sudden it would not turn on anymore, no signs of life whatsoever. I opened it up and found the power supply gone, no voltages on the output connector. Swapped the board with a known functioning one, now all supply voltages are there, but still no signs of life, except for the red LED in the SPDIF port. A rapid measuring of the test point voltages shows all the rails working except for 3.3V (both 3V3_STBY and 3V3_VCC) and all the related ones, such as 1V_VCC_CPU or 1V_VCC_CORE. The 3.3V stepdown regulator becomes rapidly very hot (as much as 85-90°C) and testing with the multimeter shows a direct short (0 ohms) from 3V3_STBY and 3V_VCC to GND. Imaging the board with a thermal camera, though, shows nothing getting warm except for the regulator, due to the high current flowing through it. Already tried desoldering the regulator and it is not shorted, as the rails still show 0 ohms to ground. I'm a bit stuck as nothing else gets warm so I can't really understand where the short lies.
Here's the schematic diagram:
https://1drv.ms/b/s!Aiwky_BwJ7fkpA3u...pD8B0?e=UjNOiq
Thank you in advance
Davide
I have a 55" LED TV made by Vestel. All of a sudden it would not turn on anymore, no signs of life whatsoever. I opened it up and found the power supply gone, no voltages on the output connector. Swapped the board with a known functioning one, now all supply voltages are there, but still no signs of life, except for the red LED in the SPDIF port. A rapid measuring of the test point voltages shows all the rails working except for 3.3V (both 3V3_STBY and 3V3_VCC) and all the related ones, such as 1V_VCC_CPU or 1V_VCC_CORE. The 3.3V stepdown regulator becomes rapidly very hot (as much as 85-90°C) and testing with the multimeter shows a direct short (0 ohms) from 3V3_STBY and 3V_VCC to GND. Imaging the board with a thermal camera, though, shows nothing getting warm except for the regulator, due to the high current flowing through it. Already tried desoldering the regulator and it is not shorted, as the rails still show 0 ohms to ground. I'm a bit stuck as nothing else gets warm so I can't really understand where the short lies.
Here's the schematic diagram:
https://1drv.ms/b/s!Aiwky_BwJ7fkpA3u...pD8B0?e=UjNOiq
Thank you in advance
Davide
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