Changhong LCD TV LED32770X accessories leakage between the special fault examples - appliance repair

Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

Factory direct 0805 blue light patch led

inductance

SMD aluminum electrolytic capacitor

A special fault, leakage between the pins of the accessories: the LCD of the Changhong LCD TV LED32770X was repaired the day before yesterday, as shown in the figure:
The power-on lamp flashes and does not turn on. Users report that they sometimes work at home for a minute or two to shut down, no longer boot, and sometimes completely normal.
Disassemble the machine to measure +5VSTB 5.2V, ON/OFF 4.4V, judge that the motherboard has been powered on, 24V 0V is not normal.
U401 1275A 6 feet 0V, U402K feet 14.4V, A feet 0V, R feet 0.44V. Analysis: U402 is a 431 precision sampler, the R pin reaches 2.5V, the K pin is turned on, and the circuit is judged to be normal. This is a protection circuit with low input voltage.
The detection and processing of the resistive components are normal, but the Internet search circuit diagram was not found, but found a case of repair, the faulty part is U402, try to replace, remove and find the problem.

The R and A feet are plated with a layer of things, bright, legendary ionization.




I wonder if everyone has encountered it?
In the past, Sharp's remote control receiver was prone to this phenomenon. It was used on air conditioners, sometimes remotely, and sometimes not.
That repair post is also on this forum, I don't know how to send a link.