Samsung LN-T405HA power supply clicking

[pop70458]

The power supply keeps clicking and never powers on. The voltages fluctuate with the clicking of the relay. The measurements below are the highest before the relay clicks and the voltage drops out.

1.power on/off ------ 3.66v
2. NC
3.stb 5.2v-------------5.2V
4.GND
5.GND
6.GND
7.12V -----------------11.94V
8.12V -----------------11.94V
9.GND
10.GND
11.GND
12.GND
13.5.4V----------------5.2V
14.5.4V----------------5.2V
15.5.4V----------------5.2V
16.5.4V----------------5.2V
17.GND
18.GND
19.13V----------------13.61V
20.GND
21.13V----------------13.61V
22.13V--------------- 13.61V
23.NC
24.NC

[budm]

Re: Samsung LN-T405HA power supply clicking

'1.power on/off ------ 3.66v' Is this command signal swing up up and down from <1V to >2.5V?
5.2VSTBY is steady?
Power supply/Inverter board P/N BN44-??????

[pop70458]

Re: Samsung LN-T405HA power supply clicking

The power on\off fluctuates from 3.66 to 0.03.
The 5.2vSTBY is steady and the power supply inverter board is a BN44-00167A.

Thanks for the reply.

[budm]

Re: Samsung LN-T405HA power supply clicking

The power on/off (PS-ON) is generated by the main board, so that will be the board you need to check out.
Do you know the history of this TV?

[budm]

Re: Samsung LN-T405HA power supply clicking

Power supply diagram.

[pop70458]

Re: Samsung LN-T405HA power supply clicking

I got it from somebody who said it was clicking. I removed the metal shield from the main board and changed the caps on the top right of the power board with panasonic low esr caps.

[budm]

Re: Samsung LN-T405HA power supply clicking

Did the symptom change when you heat that area of the main board with hair dryer?

[pop70458]

Re: Samsung LN-T405HA power supply clicking

I didn't heat it up yet because i wasn't sure what section to heat up. I downloaded this service manual that is supposed to be for this model tv.

[pop70458]

Re: Samsung LN-T405HA power supply clicking

I replaced the mainboard with a used one and the tv works great.

Thanks for the help.

[budm]

Re: Samsung LN-T405HA power supply clicking

Thanks for the follow-up on the repair.