Samsung UE40ES6140 doesn't turn on

[raydem]

Hello,

I have a Samsung UE40ES6140 that doesn't turn on. I found that if I disconect the ps_on signal the TV work fine, but if ps_on signal is connected not turn on and sounds (click click) in the power board. I continued investigate and found that the 5V voltage was toggle in a square signal from 5v to 3V3. I don't find the problem, I need help to solve this problem.
THe power board is BN44-00518B.

Thank you

[budm]

Re: Samsung UE40ES6140 doesn't turn on

Please upload good clear pictures of the whole backside of the TV showing all the boards, the good clear straight shots of the whole power supply board.

[raydem]

Re: Samsung UE40ES6140 doesn't turn on

I leave the images in links because I am not able to insert them in the post.


Power Board
https://ibb.co/FmM1RL4

Main board
https://ibb.co/NWS5x4S

PS_ON circuit power board
https://ibb.co/QNvBkm2

Optoacouplers in primary
https://ibb.co/NLHc09v

PS_on Circuit in main board
https://ibb.co/nk0Y8YY

[R_J]

Re: Samsung UE40ES6140 doesn't turn on

use the Go Advanced, and click on the paper clip to upload the images

[raydem]

Re: Samsung UE40ES6140 doesn't turn on

Ok, thanks.

I attached the images But in the previous links the images are bigger and better quality.

[raydem]

Re: Samsung UE40ES6140 doesn't turn on

Anyone can help me?

THank you

[dick_barton]

Re: Samsung UE40ES6140 doesn't turn on

The mainboard looks in very poor condition with quite a lot of water damage which could well be the reason why you have the problem.

With the power to the TV disconnected from the mains supply, and the TV psu connected to the mainboard use your multimeter set to ohms and measure the resistance between the voltage pins +5V, +3V3, +12v etc. to chassis to check for a short circuit.

[budm]

Re: Samsung UE40ES6140 doesn't turn on

https://www.badcaps.net/forum/attach...9&d=1570642166
1) TV unplugged from outlet.
2) Check the resistance between Emitter and Collector of Q202.
3) TV plugged into outlet then check the DC Voltage between Emitter and Base of Q202 when toggle the TV power switch on and off.

[raydem]

Re: Samsung UE40ES6140 doesn't turn on

The mainboard looks in very poor condition with quite a lot of water damage which could well be the reason why you have the problem.

With the power to the TV disconnected from the mains supply, and the TV psu connected to the mainboard use your multimeter set to ohms and measure the resistance between the voltage pins +5V, +3V3, +12v etc. to chassis to check for a short circuit.

Thanks for the answer, I know that the mainboard is in a poor condition, but it is for humidity. There not short circuit in any voltage.

[raydem]

Re: Samsung UE40ES6140 doesn't turn on

https://www.badcaps.net/forum/attach...9&d=1570642166
1) TV unplugged from outlet.
2) Check the resistance between Emitter and Collector of Q202.
3) TV plugged into outlet then check the DC Voltage between Emitter and Base of Q202 when toggle the TV power switch on and off.

The resistance beween emitter and collector is about 4k ohms. I attached 4 images of differents measurements in the transistor (all measurements are with GND), the mark of the component is XFV1, I wasn't able to find the datasheet ( that why the images). The last image is in the measurement of the near component (I think is a ferrite) is marked in the board like BD207.

I can not check the voltage with the TV on, if I don't unplug the signal PS_on. But if I remove it, in the PS_on the voltage is 3.3V in main board and power board, when turn on the TV else is 0V.

[budm]

Re: Samsung UE40ES6140 doesn't turn on

1) Are you 100% sure that Q202 Collector is connected to the PS-ON pin?
2) If Q202 (used as switch) is for the PS-ON control signal. the Base Voltage should be steady state not pulsing like you are showing. The Emitter should also be connected to GND so it should not show any pulsing Voltage on the Emitter. When TV is off the PS-ON switched Transistor is turned on by the micro controller to keep PS-ON Voltage <1V, when TV is turned on then the the switched Transistor is turned off to allow the PS-ON Voltage to go >2V to turn on the power supply.
"I can not check the voltage with the TV on, if I don't unplug the signal PS_on" Yes you can check the Voltage without unplugging the PS-ON wire since we are looking to see if the switched Transistor is being toggle ON or OFF or not. May be you do not understand how the PS-ON and other control signals work.
So just to be clear, if you disconnect the PS-ON wire, the TV works fine with pictures and audio, correct?

[budm]

Re: Samsung UE40ES6140 doesn't turn on

BTW, this the typical Control signals and how they are controlled.

[raydem]

Re: Samsung UE40ES6140 doesn't turn on

1) Are you 100% sure that Q202 Collector is connected to the PS-ON pin?

I don't know the pinout of the mosfet or transistor. The middle pin of the component is connected to PS_ON trought a resistor.

2) If Q202 (used as switch) is for the PS-ON control signal. the Base Voltage should be steady state not pulsing like you are showing. The Emitter should also be connected to GND so it should not show any pulsing Voltage on the Emitter. When TV is off the PS-ON switched Transistor is turned on by the micro controller to keep PS-ON Voltage <1V, when TV is turned on then the the switched Transistor is turned off to allow the PS-ON Voltage to go >2V to turn on the power supply.
"I can not check the voltage with the TV on, if I don't unplug the signal PS_on" Yes you can check the Voltage without unplugging the PS-ON wire since we are looking to see if the switched Transistor is being toggle ON or OFF or not. May be you do not understand how the PS-ON and other control signals work.
So just to be clear, if you disconnect the PS-ON wire, the TV works fine with pictures and audio, correct?

Yes, I know that PS_ON signal has to be constant, that why it is strange for me. If I disconnect PS-ON, the signal is normal in the main board. When turn on the TV appear 3,3V and when I turn off it is 0V. In the power board the signal always is in 3V.

With the PS_ON wire connected the transistor is always toggle ON/OFF as the pictures that I attached. That is why I can't measure the PS_ON signal without disconnected it.

Yes, if I disconnect the PS-ON wire the TV works fine, audio and pictures are ok.

P.D. Sorry for my English, maybe I am not able to explain things well.

[raydem]

Re: Samsung UE40ES6140 doesn't turn on

I think the problem is in the power board. Because when I remove PS_ON wire and turn on the TV, the signal change to 3.3V. I am going to remove the PS_ON components in the power board. I will write when I do it.

[budm]

Re: Samsung UE40ES6140 doesn't turn on

I think the problem is in the power board. Because when I remove PS_ON wire and turn on the TV, the signal change to 3.3V. I am going to remove the PS_ON components in the power board. I will write when I do it.

I do not think you understand how the power supply and the PS-ON works, Of course the PS-ON pin Voltage on the power supply board will go high and TV will work since the switched Transistor on the main board will no longer hold the PS-ON low, the PS-ON on the power supply board has pull-up resistor RM867 for self test. The Transistor on the main board is not being turned off so it does not allow the PS-ON to go high.
https://www.badcaps.net/forum/attach...7&d=1570642166
BTW, some one worked on the board, very poor quality works on that RM867/868 on the power supply board.

Q202 pin out, and like I said you need to check the DC Voltage with ALL cables back in place and toggle the power switch on and off and see what is happening on the Base pin of Q202, we want to know if the micro controller is turning the Q202 on and off or not.

[nomoresonys]

Re: Samsung UE40ES6140 doesn't turn on

I was thinking mainboard issue, do Bud's test.

[raydem]

Re: Samsung UE40ES6140 doesn't turn on

thank you, but I think that we don't undestand each other. The last images (with the osciloscope) that I attached are the DC voltages of the Q202 with all cables connected. If I toggle the power switch, the result doesn't change, are the same that the images.

[budm]

Re: Samsung UE40ES6140 doesn't turn on

What did you used for the Oscilloscope ground and was the main board grounded to the chassis?

[raydem]

Re: Samsung UE40ES6140 doesn't turn on

What did you used for the Oscilloscope ground and was the main board grounded to the chassis?

Hello Budm, I used a probe and yes it is connected to the chassis.

I removed R212 in the main board and I can measure the voltages in the transistor. I leave you the measures.

With the power off.
Base: 3.3V
Collector: 3.3V
Emitter: 3.3V

With the power on
Base: 0.6V
Collector: 3.3V
Emitter : 3.3V

I followed the wire PS_ON in the main board and in the end is the wt61p805. The micro controller works fine, if turn on the TV it toggle to 0V and If turn off the TV toggle to 3.3V.

For a second test, I removed R206,R222 and Q202. I connected PS_ON to 0V but the problem is the same, doesn't work. A5V in the power board toggle continuos all the time.

[budm]

Re: Samsung UE40ES6140 doesn't turn on

"I followed the wire PS_ON in the main board and in the end is the wt61p805. The micro controller works fine, if turn on the TV it toggle to 0V and If turn off the TV toggle to 3.3V."
But you have indicated that the PS-ON pin of the main board is connected to the Collector of Q202 via resistor R211 (https://www.badcaps.net/forum/attach...7&d=1571155021), so now you are saying PS-ON is connected directly to the wt61p805 pin?