lcd tv SAMSUNG LE40R71B not work ,relay clicking

[ANDRASONI LUCIAN]

I have this TV equipped with the source BN44-00134A.Tv does not start, it is heard how the relay is continuously coupling and disconnecting. The stable voltage drop is STB = 6.5V, P-ON / OFF varies between 0.2-2.5V in normal operation = 2.6V) PFC between 360-385V (when going is 382V). All electrolytes, secondary-primary, have been changed, except the 220uF / 450V which is ok. In this state, if measure the voltage on the pins 1-2 to optocouplePCS802, the relay stay connect and tv work normally . I have replaced the PCS802,801, the ICS 802 (KIA431), the QP803, the QS801, the QS802 checked. If I stop it restart (unplugged) in a few minutes, it works normally, if I leave it a little longer, the defect returns. Any suggestion is welcome, I do not think it would be the problem mainboard. Thank you!
I attach the power supply+ inverter schematic model BN44-00134A

[nomoresonys]

Re: lcd tv SAMSUNG LE40R71B not work ,relay clicking

Try a reset and or firmware update, might not fix it but won't hurt any.

[nomoresonys]

Re: lcd tv SAMSUNG LE40R71B not work ,relay clicking

Test connector from mainboard to powerboard on powerboard side with all boards hooked up, test with tv plugged in but off then hit power, report both conditions here, give pin number, pin description/name and condition on and off.

[nomoresonys]

Re: lcd tv SAMSUNG LE40R71B not work ,relay clicking

Could try heating mainboard with hairdryer, small section at a time be sure n heat the capacitors on mainboard too and see if there's any change.

[ANDRASONI LUCIAN]

Re: lcd tv SAMSUNG LE40R71B not work ,relay clicking

Thanks for the reply, I reset, but nothing has changed. When it normally works the voltages are the ones written on the board and when it does not go (the relay click) the only correct voltage is STB (stand by) = 6.44V

[R_J]

Re: lcd tv SAMSUNG LE40R71B not work ,relay clicking

Check and resolder all the transformer pins and also any of the fets/diodes etc mounted to heatsinks, I would start with this.

Sometimes these similar boards can also have the relay contacts go bad and cause NT801 to fail.
When power on is applied the relay contacts will short out NT801, if they don't the power supply will not operate properly.

[budm]

Re: lcd tv SAMSUNG LE40R71B not work ,relay clicking

1) The stby Voltage is 5.4V not 6.4V.
2) You can run the power supply board by itself (you must disconnect the cable going to the mai board first) and force it on by using 1K resistor between 5.4VSTBY and the P-ON/OFF pin, it should then come on and stays on with all the Voltages present.
If the 5.4V stby is steady then I suspect bad main board that is sending out steady PS-ON signal.
Pictures provided by shopjimmy. BN44-00134A.

[ANDRASONI LUCIAN]

Re: lcd tv SAMSUNG LE40R71B not work ,relay clicking

On the CNM801 coupler, pin 2, the voltage STB = 6.5V, see schematic diagram...,
anyway solved by replacing the eeprom 24C32 (IC903) with empty memory (FF). Thanks!