Hisense LCD TV TLM42V78K crash repair example - home appliance repair

Hisense TLM42V78K LCD TV crashed.
Check the power board output voltage and all voltages are normal. The problem lies with the motherboard. Check the power supply of the motherboard data memory DRAM = 0.92V (normally 1.09V). Check that the resistance of the DRAM to ground is normal, indicating that the DRAM is not broken. Check its power supply DC-DC circuit diagram. Check that the power supply of U3 is 5V and is normal. Check that the output of U3 is faulty. =0.92V, I checked D62 and it was good. Replacing it with U3 didn't work, and finally I tried C512.