Samsung UN40ES6100, Power supply issue

[crabn]

Re: Samsung UN40ES6100, Power supply issue

OK, I traced out the function of that diode DQ951 & resistor RQ951 parallel connection, they are for the power supply for the LED driver circuit negative return of the bridge rectifier DIODE DM851~854, so instead of having the negative of the power supply connected directly to the cold side circuit ground, it goes to GND through that diode/resistor parallel connection so the Vdrops on that resistor (it is basically monitoring the current draw in the LED power supply section) is being used to feed pin 5 of the LED driver IC9101.
So on the old board what resistance (off the board) do you have for that diode?
What DCV do you have between the two legs of the main filter cap CP814S? It should be around 380~400VDC range and steady. You can run the power supply board by itself to check the Voltages.

The guy at (https://www.badcaps.net/forum/showthread.php?t=42434) claimed that the flickering backlight is due to bad IC9101. How do I test it?

[CapLeaker]

Re: Samsung UN40ES6100, Power supply issue

It is stable at 0V if I did not press "Turn on" button on the remote. No click sound yet
It is between 0-3.2V when I pressed "Turn on" button on the remote. There is click sound now

Re read my last post, that isn't what I had asked for.

[crabn]

Re: Samsung UN40ES6100, Power supply issue

Re read my last post, that isn't what I had asked for.

What I did is:

Case 1: (1) Everything unplugged, (2) Plug in mainboard, (3) Plug in power cord, (4) Measured Voltage = 0
Case 2: (1) Everything unplugged, (2) Plug in mainboard, (3) Plug in power cord, (4) Turn it on using remote, (5) Measured voltage = 0-3.2V

Is something wrong?

[CapLeaker]

Re: Samsung UN40ES6100, Power supply issue

Yes. I asked you to unplug it all, the main board, back lights, everything. Then plug the PSU into mains and see if the A5V rail (pin12) is stable.

[budm]

Re: Samsung UN40ES6100, Power supply issue

The guy at (https://www.badcaps.net/forum/showthread.php?t=42434) claimed that the flickering backlight is due to bad IC9101. How do I test it?

Right now we need to find out if the A5V is stable or not when running the power supply board by ITSELF (NOTHING connected to the board except the power cord).
if the A5V is not stable, nothing will be stable either.

[crabn]

Re: Samsung UN40ES6100, Power supply issue

Right now we need to find out if the A5V is stable or not when running the power supply board by ITSELF (NOTHING connected to the board except the power cord).
if the A5V is not stable, nothing will be stable either.

A5V is not stable. It is bouncing between 0.002-5.2V. There is clicking sound. All cable unplugged

[crabn]

Re: Samsung UN40ES6100, Power supply issue

A5V is not stable. It is bouncing between 0.002-5.2V. There is clicking sound. All cable unplugged

Budm: Do you have any comment on this?

[budm]

Re: Samsung UN40ES6100, Power supply issue

Well, I will have to spend time looking in the 5VSTBY section and trace out the circuits. My be bad startup cap, bad diode in the cold side of the 5VSTBY supply, etc...

[crabn]

Re: Samsung UN40ES6100, Power supply issue

Well, I will have to spend time looking in the 5VSTBY section and trace out the circuits. My be bad startup cap, bad diode in the cold side of the 5VSTBY supply, etc...

Thank you, Budm. I am looking forward to hearing from you soon.

[dskall]

Re: Samsung UN40ES6100, Power supply issue

In meantime you might be looking for bad solder connections. Resolder anything looks suspicious

[crabn]

Re: Samsung UN40ES6100, Power supply issue

Sure. I will do

[crabn]

Re: Samsung UN40ES6100, Power supply issue

Hi Everyone,

I got a non-working Samsung TV UN40ES6100. It does not have any power including standby light.
There is several with power supply:

1) Fuse nearby AC inlet blown
2) Diode DQ851 shorted
3) One of the MOSFETs (Part No: 13NM60N) cracked

Then I got a replacement working power supply. It was working fine for a few hours. I tried to turn it on next day. It won't turn on any more. There is standby light. Here are some measurements:

1) Voltage at Fuse: 50 V AC
2) Voltage at C9110 and C9111: not stable 191V
3) Diode DQ851 got shorted again
4) Unplug cable from PSU to mainboard: backlight keeps flashing on and off.

My question is what cause the DQ851 being shorted?
Any other comments are welcome.

Thanks.

I checked the board and found no bad soldering.

So I went back to the old board and replaced shorted fuse and cracked MOSFET (Part No: 13NM60N). It is working now. Except wifi does not work, hardwire is working.

My question is how to test the MOSFET mentioned above? I would want to check if this MOSFET on new board is working or not.

Thanks.

[budm]

Re: Samsung UN40ES6100, Power supply issue

That MOSFET is for the PFC Voltage booster, common failure mode for that one is shorts and it will cause the main fuse to blow.
I just do not have the time to trace out the standby power supply section yet, it is not easy, very time consuming.

[Davi.p]

Re: Samsung UN40ES6100, Power supply issue

"I went back to the old board and replaced shorted fuse and cracked MOSFET (Part No: 13NM60N). It is working now"
If you learn to spend a little time searching for faults on boards, you don't have to mess with used boards, remember i read many threads on forums and that there are many situation when the user, not so expert, go to sell boards without be able to test them, and in critical situation, so if you buy from a unknown or a private do many question before buy. I would return the psu back and fuck off further inspections..
bye.

[Zaman Kay]

Re: Samsung UN40ES6100, Power supply issue

Hi. It is posible to replace DQ851 to diode sr2100? I cant find sr210 in my place.

[R_J]

Re: Samsung UN40ES6100, Power supply issue

What is wrong with D851? If it checks shorted in circuit, that is normal, remove one end to check it out of circuit.
Are you sure about the original number? sr210 is a surface mount diode DQ851 is a axil lead diode.

[Zaman Kay]

Re: Samsung UN40ES6100, Power supply issue

I check it out of circuit by remove both end. Its shorted. But i've lost it. Drop itsomewhere. Dq851 is label on pcb where the diode locate. And sr210 is written on the diode.