Skyworth LCD TV 32E82RD indicator light can not be turned on and overhaul - android - Phones Developers

Probe domestic switch needle KG-300K needle head diameter is 3.0mm normally open switch needle

Manufacturers produce direct sales LED lamp bead patch lighting products 0805 white light super bright indicator light dedicated

TP-IP4220CZ6 5V 0.35PF breakdown voltage 6V SOT

Symptom: The indicator light is green, indicating that it is already on, but the screen is not lit and there is no accompanying sound.
Repair process: Test standby 5V power supply voltage, normal. The voltage across C508 is 380V, which is slightly fluctuating, indicating that the PFC circuit works normally. The 12V voltage is measured at 1.8-3.4V, and the 24V voltage fluctuates at 15-17V, which is abnormal.
Remove the power board and repair it separately. Connect the D107 positive terminal to a 10K power supply to the standby 5V power supply to simulate the power on state. At no load, the 12V voltage fluctuates at 5-6V first, then rises to about 13V, and 24V first rises to about 27V after 10V fluctuations. When a 100W bulb is connected to each of the 12V and 24V power supplies, the 12V and 24 are both low, similar to the poor load capacity of the power supply. The b of Q613 in the protection circuit is extremely 0V, indicating that the protection circuit is not activated, and it can be determined that the fault is not caused by the protection circuit.
Check the 12V and 24V generating circuits. The 6-pin (VCC) of IC607 (FA5641) has 16.5V, and the 8-pin (high-voltage detection) has 17.5V, which is normal. It was found that Q103 (2222A) was measured with x10K file and found that its ce junction was slightly leaky, and it was reversed with Q105 (2222A). Check the optocoupler is normal, replace the FA5641 failure. Careful inspection of the 12V and 24V generating circuit components, no gain. It is suspected that the switching transformer T601 (5101-06012T-0000 BCK-40-012T) is not good, but there is no switch in the hands of the transformer can be replaced.
Suddenly, 12V and 24V were normal during the repair. The machine was installed. The test machine just started normal. After one minute, the backlight flashed and the sound was accompanied by a pause. The T601 was severely hot and could smell a burnt smell. The smell. After observing T601, T601 found that the primary coil had two tight lead pressures. Try to pull it out and find that the lead of M31 is pressed to see the copper inside. It is estimated that there is a short circuit. After unplugging, seal with 704 glue, test machine, everything is normal, T601 temperature is normal, troubleshooting.