Samsung UE22ES5000 Led tv no standby

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

Resistance across cm867 is 7.2k, but across cm864 it starts at 3meg and eventually drops down to about 30k before going back up again.

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

Anymore help on this would be greatly appreciated.

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

I still need help on this if anyone can help it would be much appreciated.
Alan

[budm]

Re: Samsung UE22ES5000 Led tv no standby

Right now that 12V power supply section is not making any sense, the resistance of the first filter cap at the Cathode of DM861 is 30K so that should not load down the 12V output , and since the switched MOSFET (QM861) for the switched 12V should not be on unless PS-ON is present and the resistance of the filter cap CM867 is 7K2 Ohms so that is not problem either.
What resistance do you get reading between the two leg of DM861 when it is soldered back into the board?

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

Hi budm and thank you for your help again. The readings across the diode DM861 is erratic. I get 295 ohm with negative on the cathode and from 3meg dropping to 7k then back up when positive is on the cathode. This board is driving me crazy.

[budm]

Re: Samsung UE22ES5000 Led tv no standby

That is strange reading of 295 Ohms.
Can you un-solder the Source pin of switched 12V MOSFET (QM861) to see if 5V will be stable?
It drives me crazy too since it is just simple always on power supply board.

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

I got a reading of 2.4 to 2.7 volts.
Do you think it has anything to do with the shunt regulator icm861 (top right on board TO-92 package) which is a kia431a?

And how would I test it?
Alan

[Davi.p]

Re: Samsung UE22ES5000 Led tv no standby

Budm was meaning if A5v is stable... B5v is the switched one so if PWR-On signal malfunctions the gates of both smd power mosfets doesn't let output on-state tensions on the connector.. if A5V is stable (pin 12 output connector) then resolder source of QM861, desolder ZDQ851, make a jumper [P-ON]-GND and watch connector outputs, if ok replace the zener.

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

Budm was meaning if A5v is stable... B5v is the switched one so if PWR-On signal malfunctions the gates of both smd power mosfets doesn't let output on-state tensions on the connector.. if A5V is stable (pin 12 output connector) then resolder source of QM861, desolder ZDQ851, make a jumper [P-ON]-GND and watch connector outputs, if ok replace the zener.

Hi. Yes I took the reading from A5V. It is bouncing around at 2.4 to 2.7v

[Davi.p]

Re: Samsung UE22ES5000 Led tv no standby

OK, you can: unsolder again DM861 cathode and connect a load of about 0,5-1A to the A5V, retest A5V, with and whitout load..

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

How do I go about adding a 500ma load?

[Davi.p]

Re: Samsung UE22ES5000 Led tv no standby

5V/0,5A=2,5Ohm 3>5W resistor at the A5v output..

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

5V/0,5A=2,5Ohm 3>5W resistor at the A5v output..

Ok I will have to dig around for a 3 to 5w resistor. I thought that 5/0.5 was 10 Ohms though. Or am I missing something.
Alan

[budm]

Re: Samsung UE22ES5000 Led tv no standby

Must be typo, yes, it should be 10 Ohms so it will draw 0.50A from 5V supply.

[Davi.p]

Re: Samsung UE22ES5000 Led tv no standby

Sorry 10 ohms 10watt..

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

I have ordered the resistor and will update you when I have tested the circuit. Many thanks for all your help.

[Atavares]

Re: Samsung UE22ES5000 Led tv no standby

Did you replace CM808 capacitor?
What number diode did you use to replace DM861?
Check that QM861 is not shorted

Also what is the voltage measured at the cathode of DM861

Hi R_J!

Do you know the ref. of the QM861, i have the same problem, but my QM is shorted.