Samsung LN22A450C1DXZA Dead main board

[budm]

Just fixed this 22" Samsung, the 13V from power supply is OK, Power supply for the inverter is OK, I can force the backlight on OK, but the main board has no 5V standby, no indicator light.
Download the service manual from ELEKTROTAYA and start checking the voltage on the 5V standby switching power supply section. U201 has the 13v input on pin 8 but I have no output on C221. I suspect bad IC but decide to do some resistance checking first since it has many MLLC (Multi Layer Ceramic Cap) around the circuits. The resistance reading on pin 7 was 2.3K which seems to be way too low since it has 30K (R216) and C212 (0.22uf 25v) to ground. I remove the C212 and check the resistance again, now it read around 30K. Check the leakage resistance of C212, it shows 2.4K.
So I replaced the C212, now I have my 5V and red power light, TV fires up and works again.

[retiredcaps]

Re: Samsung LN22A450C1DXZA Dead main board

Sure, it takes me 20 months to figure out a similar problem and you probably did it in under 20 minutes!!

Good job on finding that shorted cap.

[budm]

Re: Samsung LN22A450C1DXZA Dead main board

Thanks, If I did not have the diagram, then that will be another story. The replacement board is about $30, but I did not want to give up.

[manoftheyear]

Re: Samsung LN22A450C1DXZA Dead main board

How typical is it to see a bad MLCC on a mainboard? Have you had many cases like this before?

[budm]

Re: Samsung LN22A450C1DXZA Dead main board

T-con board board also has failed MLCC. MLCC can easily be damaged and has to be handled properly during installation and the location it is installed, it does not like to be flexed, if it is cracked, it will short out. So do not flex the board you are working on too much
Any component will fail on any boards.