Unknown ic in power supply of TCL U55E5800FS TV

[Kartman]

I have a TCL U55E5800 tv whose power supply has failed. It looks like the root cause was a 100pF 1kV cap as part of the snubber that died then caused the gate junction of the mosfet to break down and blow up the controller chip. The cap, mosfet and diode have been identified, but the sot23-6 pwm controller is dead. How do I know this? The junction between the gate drive and 0V is a couple of Ohms. For those who have a schematic, the designator is U302

Anyways, the markings are: 283G12 and 284B. 

From looking at the circuit, the pins roughly are:
1 VCC
2 current sense
3 gate drive
4 0V
5 some sort of sense input
6 feedback

I had a look at OnSemi, their NCP2150 sort of looked similar, but rotated 180degrees.

If anyone has the schematic, parts list or a suggestion it would be appreciated.

[amyk]

OB2283A

Search pictures of it to confirm.

Edit: OB2283A, not just 2283. Details here: https://www.wendangwang.com/doc/0582a3710bac1bbae9b36b38

[Kartman]

Many thanks! It looks like the chip. The next problem is where to buy some.

[don.r]

You can take your chances on aliexpress but it might not be genuine.

https://www.aliexpress.com/item/32790107064.html

[Kartman]

I managed to have success in repairing this tv. It was not straightforward - the OB2283 chip is close, but not quite the right one methinks. The OB2283 has latching over temp/over volt circuitry, whereas the original chip (whatever that is) did not. After much fiddling, I bridged a 33k resistor across the existing 33k resistor connected to the PRT pin. This told the chip there was no over temp and no over volts. Once i did this, the power supply jumped into life.

I got the mosfets and OB2283 chips off Aliexpress. There was a surface mount diode that I replaced with a 1N4148 leaded part and a 100pF 1kV cap replaced.

Another TV saved from the scrap heap. Thanks to all that contributed. Great success!

[amyk]

Yes, that was likely the difference between a plain OB2283 and an OB2283A.